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3.3 CANNABIS LIFE CYCLE
Marijuana plants may belong to any one of a number of varieties which follow somewhat different growth patterns. The following outline describes the more common form of growth. Differences between varieties can be thought of as variations on this standard theme.
Cannabis is an annual plant. A single season completes a generation, leaving all hope for the future to the seeds. The normal life cycle follows the general pattern described below.
Germination
With winter past, the moisture and warmth of spring stir activity in the embryo. Water is absorbed and the embryo's tissues swell and grow, splitting the seed along its suture. The radical or embryonic root appears first. Once clear of the seed, the root directs growth downward in response to gravity. Meanwhile, the seed is being lifted upward by growing cells which form the seedling's stem. Now anchored by the roots, and receiving water and nutrients, the embryonic leaves (cotyledons) unfold. They are a pair of small, somewhat oval, simple leaves, now green with chlorophyll to absorb the life-giving light. Germination is complete. The embryo has been reborn and is now a seedling living on the food it produces through photosynthesis. The process of germination is usually completed in three to 10 days.
Seedling
The second pair of leaves begins the seedling stage. They are set opposite each other and usually have a single blade. They differ from the embryonic leaves by their larger size, spearhead shape, and serrated margins. With the next pair of leaves that appears, usually each leaf has three blades and is larger still. A basic pattern has been set. Each new set of leaves will be larger, with a higher number of blades per leaf until, depending on variety, they reach their maximum number, often nine or 11. The seedling stage is completed within four to six weeks.
Vegetative Growth
This is the period of maximum growth. The plant can grow no faster than the rate that its leaves can produce energy for new growth. Each day more leaf tissue is created, increasing the overall capacity for growth. With excellent growing conditions, Cannabis has been known to grow six inches a day, although the rate is more commonly one to two inches. The number of blades on each leaf begins to decline during the middle of the vegetative stage. Then the arrangement of the leaves on the stem (phyllotaxy) changes from the usual opposite to alternate. The internodes (stem space from one pair of leaves to the next, which had been increasing in length) begin to decrease, and the growth appears to be thicker. Branches which appeared in the axils of each set of leaves grow and shape the plant to its characteristic form. The vegetative stage is usually completed in the third to fifth months of growth.
Preflowering
This is a quiescent period of one to two weeks during which growth slows considerably. The plant is beginning a new program of growth as encoded in its genes. The old system is turned off and the new program beings with the appearance of the first flowers.
Flowering
Cannabis is dioecious: each plant produces either male or female flowers, and is considered either a male or female plant. Male plants usually start to flowers about one month before the female; however, there is sufficient overlap to ensure pollination. First the upper internodes elongate; in a few days the male flowers appear. The male flowers are quite small, about 1/4 inch, and are pale green, yellow, or red/purple. They develop in dense, drooping clusters (cymes) capable of releasing clouds of pollen dust. Once pollen falls, males lose vigour and soon die.
The female flowers consists of two small (1/4 to 1/2 inch long), fuzzy white stigmas raised in a V sign and attached at the base to an ovule which is contained in a tiny green pod. The pod is formed from modified leaves (bracts and bracteoles) which envelop the developing seed. The female flowers develop tightly together to form dense clusters (racemes) or buds, cones, or colas (in this book, buds). The bloom continues until pollen reaches the flowers, fertilising them and beginning the formation of seeds. Flowering usually lasts about one or two months, but may continue longer when the plants are not pollinated and there is no killing frost.
Seed Set
A fertilised female flower develops a single seed wrapped in the bracts. In thick clusters, they form the seed-filled buds that make up most fine imported marijuana. After pollination, mature, viable seeds take from 10 days to five weeks to develop. When seeds are desired, the plant is harvested when enough seeds have reached full colour. For a fully-seeded plant this often takes place when the plant has stopped growth and is, in fact, dying. During flowering and seed set, various colours may appear. All the plant's energy goes to reproduction and the continuance of its kind. Minerals and nutrients flow from the leaves to the seeds, and the chlorophylls that give the plant its green colour disintegrate. The golds, browns, and reds which appear are from accessory pigments that formerly had been masked by chlorophyll.
Figure 30 THC potency through various growth stages in the male and female
plant
About Plants Generally
Plants use a fundamentally different "life strategy" from animals. Animals are more or less self-contained units that grow and develop to predetermined forms. They use movement and choice of behaviour to deal with the changing environments. Plants are organised more as open systems - the simple physical characteristics of the environment, such as sunlight, water, and temperature, directly control their growth, form, and life cycles. Once the seed sprouts, the plant is rooted in place and time. Since growth is regulated by the environment, development is on accordance with the plant's immediate surroundings. When a balance is struck, the strategy is a success and life flourishes.
Behaviour of a plant is not a matter of choice; it is a fixed response. On a visible level the response more often than not is growth, either a new form of growth, or specialised growth. By directly responding, plant in effect "know," for example, when to sprout, flower, or drop leaves to prepare for winter.
Everyone has seen how a plant turns toward light or can bend upward if it its stem is bent down. The plant turns by growing cells of different length on opposite sides of the stem. This effect turns or right the plant. The stimulus in the first case is light, in the second gravity, but essentially the plant responds by specialised growth. It is the same with almost all facets of a plant's live - growth is modified and controlled by the immediate environment. The influence of light, wind, rainfall, etc., interacts with the plant (its genetic make-up or genotype) to produce the individual plant (phenotype).
The life cycle of Cannabis is usually complete in four to nine months. The actual time depends on variety, but it is regulated by local growing conditions, specifically the photoperiod (length of day vs night). Cannabis is a long-night (or short-day) plant. When exposed to a period of two weeks of long nights - that is, 13 or more hours of continuous darkness each night - the plants respond by flowering. This has important implications, for it allows the grower to control the life cycle of the plant and adapt it to local growing conditions or unique situations. Since you can control flowering, you control maturation and, hence, the age of the plants at harvest.
3.4 PHOTOPERIOD AND FLOWERING
For the marijuana grower the most important plant/environment interaction to understand is the influence of the photoperiod. The photoperiod is the daily number of hours of day (light) vs. night (dark). In nature, long nights signal the plant that winter is coming and that it is time to flowers and produce seeds. As long as the day-length is long, the plants continue vegetative growth. If female flowers do appear, there will only be a few. These flowers will not form the characteristic large clusters or buds. If the days are too short, the plants flowers too soon, and remain small and underdeveloped.
The plant "senses" the longer nights by a direct interaction with light. A flowering hormone is present during all stages of growth. This hormone is sensitive to light and is rendered inactive by even low levels of light. When the dark periods are long enough, the hormones increase to a critical level that triggers the reproductive cycle. Vegetative growth ends and flowering begins.
The natural photoperiod changes with the passing of seasons. In the Northern Hemisphere, the length of daylight is longest on June 21. Day-length gradually decreases until it reaches its shortest duration on December 22. The duration of daylight then begins to increase until the cycle is completed the following June 21. Because the Earth is tilted on its axis to the sun, day-length also depends on position (or latitude) on Earth. As one moves closer to the equator, changes in the photoperiod are less drastic over the course of a year. At the equator (0 degrees altitude) day length lasts about 12.5 hours on June 21 and 11.5 hours on December 22. In Maine (about 45 degrees north), day-length varies between about 16 and nine hours. Near the Arctic Circe on June 21 there is no night. On December 22 the whole day is dark. The longer day-length toward the north prevents marijuana from flowering until later in the season. Over most of the northern half of the country, flowering is often so late that development cannot be completed before the onset of cold weather and heavy frosts.
The actual length of day largely depends on local conditions, such as cloud cover, altitude, and terrain. On a flat Midwest plain, the effective length of day is about 30 minutes longer than sunrise to sunset. In practical terms, it is little help to calculate the photoperiod, but it is important to realise how it affects the plants and how you can use it to you advantage.
Cannabis generally needs about two weeks of successive long nights before the first flowers appear. The photoperiod necessary for flowering will vary slight with (1) the variety, (2) the age of the plant, (3) its sex, and (4) growing conditions.
1. Cannabis varieties originating from more northerly climes (short growing seasons) react to as little as nine hours of night. Most of these are hemp and seed varieties that are acclimated to short growing seasons, such as the weedy hemps of Minnesota or southern Canada. Varieties from more southerly latitudes need longer nights with 11 to 13 hours of darkness. Since most marijuana plants are acclimated to southerly latitudes, they need the longer nights to flower. To be on the safe side, if you give Cannabis plant dark periods of 13 or more hours, each night for two weeks, this should be enough to trigger flowering. 2. The older a plant (the more physiologically developed), the quicker it responds to long nights. Plants five or six months old sometimes form visible flowers after only four long nights. Young marijuana plants (a month or so of age) can take up to four weeks to respond to long nights of 16 hours. 3. Both male and female Cannabis are long-night plants. Both will flower when given about two weeks of long nights. The male plant, however, will often flower fully under very long days (18 hours) and short nights (six hours). Males often flowers at about the same time they would if they were growing in their original environment. For most marijuana plants this occurs during the third to fifth month. 4. Growing conditions affect flowering in many ways (see Chapter 12). Cool temperatures (about 50F) slow down the flowering response. Cool temperatures or generally poor growing conditions affect flowering indirectly. Flower development is slower, and more time is needed to reach full bloom. Under adverse conditions, female buds will not develop to full size.
Applications of Photoperiod
The photoperiod is used to manipulate the plants in two basic ways:
1. By giving long dark periods, you can force plants to flower. 2. By preventing long nights, using artificial light to interrupt the dark period, you can force the plants to continue vegetative growth.
Outdoors
Most marijuana plants cultivated in the United States begin to flower by late August to early October and the plants are harvested from October to November. For farmers in the South, parts of the Midwest, and West Coast, this presents no problem and no special techniques are needed for normal flowering.
In much of the North and high-altitude areas, many varieties will not have time to complete flowering before fall frosts. To force the plants to flower earlier, give them longer night periods. If the plants are in containers, you can simply move them into a darkened area each evening. Plants growing in the ground can be covered with an opaque tarpaulin, black sheet plastic, or double or triple-layers black plastic trash bags. Take advantage of any natural shading because direct sunlight is difficult to screen completely. For instance, if the plants are naturally shaded in the morning hours, cover the plants each evening or night. The next morning you uncover the plants at about eight to nine o'clock. Continue the treatment each day until all the plants are showing flowers. This usually takes two weeks at most, is the plants are well developed (about four months old). For this reason, where the season starts late, it is best to start the plants indoors or in cold frames and transplant outdoors when the weather is mild. This in effect lengthens the local growing season and gives the plants another month or two to develop. By the end of August the plants are physiologically ready to flower; they sometimes do with no manipulation of the photoperiod. More often female plants show a few flowers, but the day-length prevents rapid development to large clusters. The plants seem in limbo - caught between vegetative growth and flowering. The natural day-length at this time of year will not be long enough to reverse the process, so you can discontinue the treatment when you see that the new growth is predominantly flowers.
In areas where frosts are likely to occur by early October, long-night treatments may be the only way you can harvest good-sized flower clusters. These clusters, or buds, are the most potent plant parts and make up the desired harvest. Forcing the plants to flowers early also means development while the weather is warm and the sun is shining strongly. The flower buds will form much faster, larger and reach their peak potency. A good time to start the treatments is early to middle August. This allows the plants at least four weeks of flowering while the weather is mild.
Another reason you may want to do this is to synchronise the life cycle of the plants with the indigenous vegetation. In the northeast and central states, the growing season ends quite early and much of the local vegetation dies back and changes colour. Any marijuana plants stick out like green thumbs, and the crop may get ripped off or busted. Plants treated with long nights during late July will be ready to harvest in September.
Outdoors, growers should always plant several varieties, because some may naturally flower early, even in the northern-most parts of the country. These early-maturing varieties usually come from Mexican, Central Asian, and homegrown sources. By planting several varieties, many of you will be able to find or develop an early-maturing variety after a season or two. This, of course, is an important point, because it eliminates the need for long-night treatments.
Preventing Flowers
Manipulation of the photoperiod can also prevent the plants from flowering until a desired time. For example, in Hawaii the weather is mild enough to grow winter crops. The normal summer crop is harvested anytime from September to mid-November. The winter crop is generally planted from October to December. Because the winter days are so short, the plants flower almost immediately, usually within two month. The plants are harvested in their third or fourth month and yield about 1/4 the yield of summer plants. A large Hawaiian female can yield a pound of buds. Most of the plant's overall size is reached while it is vegetatively growing. By interrupting the night period with light, you can keep these plants vegetatively growing for another month, yielding plants of about twice the size.
The amount of light needed to prevent flowering is quite small (about .03 foot candles95 - on a clear night the full moon is about .01 foot candles). However, each plant mist be illuminated fully, with the light shining over the whole plant. This might be accomplished with either electric light or a strong flashlight. The easiest way is to string incandescent bulbs, keeping them on a timer. The lights need be turned on for only a flash at any time during the night period, from about 9:00 pm to about 3:00 am. The interrupts the long night period to less then nine hours. Start these night treatments each night or two, until you want the plants to flower.
Indoors
Natural Light
Indoors, the growing season lasts all year. The night period is much easier to control. Sometimes people grow plants in their windows for more than a year without any female flowers ever forming. This is because household lamps are turned on sometime at night, illuminating the plants. Under natural light exclusively, indoor plants flower at about the same time they would outdoors (sometime a bit sooner because it is warmer indoors or the plants may be shaded). When plants are well developed and you want them to flower, make sure that no household lamps or nearby street lamps are shining on them. During late fall and winter, the natural day-length is short enough for the plants to flower naturally, if you simply keep off any lights at night that are in the same room as the plants. If you must use light, use the lowest wattage possible, such as a six-watt bulb. (The hormone is also least sensitive to blue light.) Shield the light away from the plants. Or shield the plants from any household light with aluminium foil curtains. Once the flowers are forming clusters, you can discontinue the dark treatments, especially if it is more convenient. However, if it is too soon (when you see only a few random flowers), household lights can reverse the process.
By using natural light, you can grow indoor crops all year. The winter light is weak and the days are short, so it is best to use artificial lights to supplement daylight, as well as to extend the photoperiod. The extra light will increase the growth rate of the plants and hence size and yield. You should allow winter crops to flower during late January or February, using the natural photoperiod to trigger flowering. If you wait until spring, the natural light period will be too long and may prevent flowering.
Artificial Lights
Under artificial light the photoperiod is, of course, any length you wish. The most popular way to grow with artificial lights is the harvest system. Start the plants under long light periods of from 16 to 18 hours daily. After the plants have reached a good size, usually between three and six months, shorten the light cycle to about 12 hours to force flowering.
To decide exactly when to force the plants to flower, let their growth be the determinant. If male plants are showing their flowers, then the females are physiologically ready to flower. Most of the plant's overall height is achieved during vegetative growth. Some varieties, of course, are smaller and grow more slowly than others. Wait until the plants are nearing the limits of the height of the garden or are at least five feet tall. This is large enough to support good flower development and return a good yield. If you turn down the light cycle when the plants are young and small, you'll harvest much less grass because the plants simply can't sustain a large number of flowers.
Some leaf growers prefer a continuous growth system, emphasising leaf growth and a continuous supply of grass. The light cycle is set for 18 to 24 hours a day. This prevents flowering and the plants continue their rapid vegetative growth. Growing shoots and leaves are harvested as used, and plants are removed whenever they lose their vigour and growth has noticeably slowed. New plants are started in their place. In this way, there will be plants at different growth stages, some of which will be in their rapid vegetative growth stage and will be quite potent. Male plants and some females eventually will form flowers, but the females will not form large clusters. People often use this system when the lights are permanently fixed. Small plants are raised up to the lights on tables or boxes. This garden never shuts down and yields a continuous supply of grass.
3.5 INHERENT VARIATIONS IN POTENCY
The potency of a particular marijuana sample will vary because of many factors other then the variety. Many of these have to do with the natural development of the plants and their resin glands. Environmental factors do affect potency but there are large differences in any variety. These inherent factors must be explained before we can talk of factors outside the plant that affect relative potency. Strictly environmental effects are discussed in Chapter 19.
Variations in Potency Within Varieties
There are noticeable differences in THC concentrations between plants of the same variety. Differences are large enough so that you can tall (by smoking) that certain plants are better. This is no news to homegrowers, who often find a particular plant to be outstanding. Five-fold differences in THC concentration have also shown up in research. However, when you consider a whole group of plants of the same variety, they're relatively similar in cannabinoid concentrations. Type II plants are the most variable, with individual plants much higher than other in certain canninbinoids.
Variations by Plant Part
The concentration of cannabinoids depends on the plant part, or more specifically, the concentration and development of resin glands to plant part. The female flower bracts have the highest concentration of resin glands and are usually the most potent plant parts. Seeds and roots have no resin glands. These shoe no more than traces of canninbinoids. Smoke seeds will give you a headache before you can get high. If you got high on seeds, then there were probably enough bracts adhering to the seeds to get you high. {Figure 29 The highest concentration of stalked resin glands forms a cover on the female flower bracts Resin glands beneath cystolith hairs on a leaf petiole}
Here are the potencies, in descending order, of the various plant parts:
1. Female flowering clusters. In practice you don't separate hundreds
of tiny bracts to make a joint. The whole flowering mass (seeds removed),
along with small accompanying leaves, forms the material.
2. Male flower clusters. These vary more in relative potency depending on
the strain (see "Potency by Sex," below).
3. Growing shoots. Before the plants flower, the vegetative shoots (tips)
of the main stem and branches are the most potent plant parts.
4. Leaves (a) that accompany flowers (small);
(b) along branches (medium);
(c) along main stem (large).
Generally, the smaller the leaf is, the more potent it can be.
5. Petioles (leaf stalks). Same order as leaves.
6. Stems. Same order as leaves. The smaller the stem (twig), the
higher the possible concentration of cannabinoids. Stems over 1/16"
in diameter contain only traces of cannabinoids and are not worth
smoking. The small stems that bear the flowers can be quite potent.
7. Seeds and Roots. Contain only traces (less then .01 percent) and
are not worth smoking or extracting.
This order is fairly consistent. The exceptions can be the small leaves that accompany male flowers, which are sometimes more potent than the flowers themselves. The growing shoots are sometimes more potent than the mature female flowers.
Samples of pollen show varying amounts of cannabinoids. Resin glands are found inside the anthers, alongside the developing pollen grains, and form two rows on opposite sides of each anther. Pollen grains are smaller than the heads of large resin glands ({see Plate 7}), and range from 21 to 69 micrometres in diameter21. A small amount of resin contaminates the pollen when glands rupture, but most of the THC in pollen samples comes from gland heads that fall with pollen when the flowers are shaken to collect it. One study, using pollen for the sample, found concentrations of up to 0.96 percent THC, more then enough to get you high79.
Potency by Position on Plant
The potency of marijuana on any plant increases toward the top of the plant, the topmost bud being the most potent. The bottommost leaves on the main stem are the least potent of the useable material. Along branches there is a less steep THC gradient increasing to the growing tip.
The ratios in Table 11 are representative of high-quality marijuana varieties. Plant no. 2 is an exception, with four percent THC in its lower leaves, a figure comparable to high-quality Colombian and Mexican buds in commercial grass.
Table 11 - Relationship of THC Content to Leaf Position (6
Percentage of THC by weight of Leaf from Position on plant
Plant No. 1 (SP-5) NO.2 (SP-5) NO.3 (UNC-335)
Top 6.1 6.9 4.8
Middle 3 5.5 3.1
Bottom 0.8 4 1.5
Ratio (gradient) 8:4:1 1.7:1.4:1 3:2:1
Notice the large difference in the gradients of Plants no. 1 and 2, which are from the same variety (SP-5). Like almost all characteristics of these plants, considerable variation occurs even among sibling. Our experience is that generally the better the quality of the variety, the steeper the gradient: in other words, the bigger the difference between top and bottom leaves. For example, the plants given here are high-quality type I varieties. Plant no. 1 is more typical, with its steep gradient, than no.2, where the gradient is much less pronounced. Lower-quality varieties generally do not have as steep a gradient and the ratios would look more like that of Plant no. 2.
Potency by Sex
Although marijuana lore claimed the female to be the more potent, scientists disclaimed this. But there is some truth to both sides. In fine marijuana varieties, male and female leaves average about the same in cannabinoid concentrations. Either a male or a female individual may have the highest concentration in any particular case. The largest variation is in comparing the flowers. Male flowers may be comparable to the females, or they may not even get you high. It seems that the higher the quality of the grass, the better the male flowers will be. In fine type I plants, male flowering clusters usually approach the potency of the female. In low-quality type III varieties females are usually more potent (20 to 30 percent) than the males.
Type II plants are the most variable, with large differences among individual plants. But the trend is for the females to average about 20 percent high in potency of leaves and flowers.
Table 12 - Relative Potencies of Male and Female Plants (66)
Percentage by Weight (b) of
COUNTRY OF ORIGIN SEX (a) THC CBD (C) TYPE PLANT
Mexico M 3.7 0.86 I
F 3.7 0.35
India M 4.3 0.12 I
F 1.78 0.19
Thailand M 3.2 0.08 I
F 3.2 0.42
India M 0.81 2.1 II
F 1.3 0.89
Pakistan M 1.37 1.24 II
F 0.71 1.5
Turkey M 0.84 2.11 II
F 0.92 1.33
India M 0.15 2.2 III
F 0.12 1.2
Poland M 0.04 0.97 III
F 0.06 1.1
a) M, male (staminate); F, female (pistillate). (b) Of flowering mass
with accompanying leaves. (c) Includes CBC. _
Potency by Age
In general, the longer the life cycle of the plant, the more the concentration of cannabinoids increases, as long as the plant stays health and vigorous. Actually, it is the development of the plant, rather than chronological age, that determines this difference in potency. A plant that is more developed or more mature is generally more potent.
Because you decide when to plant and/or can control the photoperiod, you also control when the plants flowers and, hence, the overall age at maturity. A six-month-old plant will generally be better than a four-month-old plant, both of which are flowering. Plants eight months old will usually be more potent than six-month-old plants. Most indoor growers plan their gardens to be about five to eight months old at harvest. Healthy plants can be extended to about 10 months. Plants older than 10 months often develop abnormally. There is usually a decline in vigour and a loss in potency. But some growers have decorative plants several years old.
Outdoor growers more often simply allow the plants to develop according to the local growing conditions which will govern their development and flowering time. Where the growing season is short, some growers start the plants indoors and transplant when the local growing season begins. This gives the plants a longer growing season.
One reason female plants are considered more potent is because of age. Males often flower in four to five months and die, while the females may continue to a ripe old age of eight or nine months, especially when they are not pollinated.
Potency by Growth Stage
Although then general trend is for the cannabinoid concentration to increase with age, this is not a matter of the simple addition or accumulation of cannabinoids. The concentration of cannabinoids changes with the general metabolic rate of the plant, and can be related to the plant's growth pattern or life cycle. Figure 30 shows a hypothetical curve following the concentration of THC from the upper leaves and growing tips of a male and female plant.
Notice that THC increases immediately with germination and establishment of the seedling, and continues to rise until the plant enters its vegetative stage. At this point, the plant is well-formed, with a sturdy stem, and no longer looks fragile. As the plant;s rate of growth increases, there is a corresponding rise in THC that continues throughout the vegetative stage until a plateau is reached. Before the plateau is reached the arrangement of leaves on the stem (phyllotaxy) changes from opposite to alternate. The plateau is maintained until the plant's rapid growth all but stops and the plant has entered preflowering. By this time, the branches have formed the plant to its characteristic shape. Preflowering lasts about one to two weeks, during which THC concentration falls until the appearance of the first flowers.
For the male plant, preflowering ends with renewed growth. This lengthens the uppermost internodes and the first male flower buds appear. THC immediately increases with the development of the male flower clusters, and reaches its peak when most of the flowers are fully formed and a few are beginning to release pollen. After pollen release, the male normally loses vigour and THC content slowly declining until the plant is cured and stored.
Female plants reach their maximum THC when the plants are in full bloom. Full bloom is when the plant has filled out with well-formed flower clusters, but flowers are still slowly forming. Most of the stigmas will still be white and healthy.
Flowering lasts anywhere from two to 10 weeks, depending on whether the plants are pollinated or not, as well as on variety and the environment. (See Chapter 20 for details.) THC content declines as the formation of new flowers slows and the majority of the stigmas begin to brown. The only changes you may see in the plants are the maturation of the seeds and the loss of green colour in the leaves and flowers. In some cases the plant's apparent resin (its look and feel) increases during the last few weeks of life while the THC concentration is still declining.
You may feel that you should only pick marijuana when the plants are in full bloom, but this is not the case. Think of the garden as a continuous supply of grass. You can never be sure of the fate of your plants. The biggest problem with outdoor growing is that there is a good chance that the plants will be ripped off before you plan to harvest. It is much better to harvest grass during the course of a season, assuring yourself a return for your efforts. For example, during the third month of growth, you could cut back the growing tips, which should be quite potent, often more potent than Figure 30 suggests. This doesn't mean there will be less to harvest at season's end. In fact, the plant will be forced to develop its branches, possible yielding a larger plant.
Common sense tells you that it is always best to test one sample before you harvest. By taking one tip, curing and smoking, you'll know whether it's worthwhile to harvest more at that time or to wait longer. When a tip is about equal to its parents' potency, then definitely harvest more growing tips. This peak high often occurs during the middle to late rapid, vegetative-growth stage.
The reader should keep in mind that Figure 30 serves only as an example. Chronological age is not as important as the physiological age of the plant. In this graph, the life of the plants is about six months. But the life cycle depends on the particular variety and the growing conditions, which strongly influence the rate of development. (For details on how to use the graph, see Chapter 20.) The important facts that the reader should get from the graph are that the potency of the grass can decrease as well as increase during the plant's life cycle. Actual studies of the cyclic variations in potency over the course of a season have shown much more complicated rhythms, with many more peaks and valleys then here 71,74,80,86,92. Most varieties will more or less follow a growth pattern as described. Changes in the plant's development, such as phyllotaxy and growth rate, are cues to changes in THC concentration. Secondly, the growing tips of the main stem and branches can be very potent. Growers do not have to wait until flowers form to harvest top-quality smoke.
3.6 Cultivation: Indoors or Outdoors?
The basic elements of the environment (light, water, air, and soil) provide plants with their fundamental needs. These environmental factors affect the growth rates of plants, as well as their life cycles. If one factor is deficient, growth rate and vigour will wan regardless of the other three. For instance, with low light, the growth will be limited no matter how fertile and moist the soil is. In the same sense, if soil minerals are scarce, the growth rate will be limited no matter how you increase the light.
Photosynthesis
Cannabis, like all green plants, manufacturers its food through the process photosynthesis. Unlike animals, which depend on pre-formed food for survival, plants can use energy from light to form food (carbohydrates) from simple inorganic molecules absorbed from the air and soil.
Plants absorb light energy through pigments that are concentrated in the leaf cells. These pigments are also found in most of the aboveground parts of the plant. The most abundant pigment is chlorophyll, which gives the plants their green colour. The energy absorbed is stored in chemical compounds such as ATP and NADPH2. ((ATP, adenosine-triphosphate; NADPH2, nicotinamide-adenine-dinucleotide-phosphate.)) These are storage/transfer compounds that function to transfer energy and matter in the living system. ATP transfers energy that fuels the reactions for the making of carbohydrates as well as most other metabolic functions. NADPH2 transfers electrons, usually as hydrogen, for the synthesis of carbohydrates as well as other compounds.
The raw material for the synthesis of carbohydrates (CH2O)n comes from carbon dioxide (CO2) and water (H2O). Carbon dioxide is absorbed primarily from the air, but can also be absorbed from the soil and secondarily from the air.
Photosynthesis is summarised as follow:
light energy ------- ATP + NADPH2
CO2 + H2O ------- (CH2O)n + O2
For more complex bio-molecules such as amino acids and proteins, the plant absorbs minerals (including nitrogen, phosphorus, and sulfur) from the soil. Carbohydrates provide food energy for the plant using processes similar to those that occur in humans. They also form the basic building blocks for plant tissues. For example, the sugar glucose (CH2O)6 is strung and bonded to farm long chains of cellulose, the most abundant organic compound on earth. About 80 percent of the structure of the plant's cells is made from cellulose.
The plant is a living thing existing in a holistic world; a myriad of factors affect its life. However, good cultivation techniques require attention to only four basic growth factors. With this accomplished, the plants will do the rest.
As grower, your strategy is to bring out the plant's natural qualities. The cannabinoids are natural to the plants. Seeds from potent marijuana grow into potent marijuana plants when they are nurtured to a full and healthy maturity.
Since most marijuana plants are adapted to tropical or semitropical climates, it is up to the grower to make the transition to local growing conditions harmonious. The requires sensible gardening techniques and, in some cases, manipulation of the photoperiod. There is no magic button to push or secret fertiliser to sue. The secret of potency lies within the embryo. The environment can and does affect potency, as it does most aspects of the plant's life. However, environmental factors are secondary to the plant's heritage (genetic potential).
Indoors vs. Outdoors
At this point the book divides into separate indoor and outdoor cultivation sections, and you may wonder whether it is better to grow the plant indoors or outdoors. Each alternative has advantages and disadvantages. It is usually better to grow the plants outdoors if possible, because the plants can grow much larger and faster than indoors. Indoors presents space and light limitations. It is possible to grow a 15-foot bush indoors, but this is unrealistic in most home. There simply isn't enough room or light for such a large plant. Outdoor gardens return a much higher yield for the effort and expense. most indoor gardeners buy soil and may have to buy electric lights. So there is an initial investment of anywhere from $10 on up.
On the other hand, outdoor plants are more likely to be seen. Many gardens get ripped off, and busts are a constant threat. Indoor gardens are much less likely to be discovered. Gardening indoors allows the grower closer contact with the plants. The plants can be grown all year long; it is an easy matter to control their growth cycles and flowering. Probably the biggest attraction of indoor gardens is that they are beautiful to watch and easy to set up anywhere.
One popular compromise is to construct a simple greenhouse. Use plastic to either enclose part of a porch or to cover a frame built against the house.
The potency of the plants doesn't depend on whether they are grown indoors or outdoors. As long as you grow healthy plants that reach maturity and complete their life cycle, the grass can be as good as any you've ever smoked.
Marijuana plants may belong to any one of a number of varieties which follow somewhat different growth patterns. The following outline describes the more common form of growth. Differences between varieties can be thought of as variations on this standard theme.
Cannabis is an annual plant. A single season completes a generation, leaving all hope for the future to the seeds. The normal life cycle follows the general pattern described below.
Germination
With winter past, the moisture and warmth of spring stir activity in the embryo. Water is absorbed and the embryo's tissues swell and grow, splitting the seed along its suture. The radical or embryonic root appears first. Once clear of the seed, the root directs growth downward in response to gravity. Meanwhile, the seed is being lifted upward by growing cells which form the seedling's stem. Now anchored by the roots, and receiving water and nutrients, the embryonic leaves (cotyledons) unfold. They are a pair of small, somewhat oval, simple leaves, now green with chlorophyll to absorb the life-giving light. Germination is complete. The embryo has been reborn and is now a seedling living on the food it produces through photosynthesis. The process of germination is usually completed in three to 10 days.
Seedling
The second pair of leaves begins the seedling stage. They are set opposite each other and usually have a single blade. They differ from the embryonic leaves by their larger size, spearhead shape, and serrated margins. With the next pair of leaves that appears, usually each leaf has three blades and is larger still. A basic pattern has been set. Each new set of leaves will be larger, with a higher number of blades per leaf until, depending on variety, they reach their maximum number, often nine or 11. The seedling stage is completed within four to six weeks.
Vegetative Growth
This is the period of maximum growth. The plant can grow no faster than the rate that its leaves can produce energy for new growth. Each day more leaf tissue is created, increasing the overall capacity for growth. With excellent growing conditions, Cannabis has been known to grow six inches a day, although the rate is more commonly one to two inches. The number of blades on each leaf begins to decline during the middle of the vegetative stage. Then the arrangement of the leaves on the stem (phyllotaxy) changes from the usual opposite to alternate. The internodes (stem space from one pair of leaves to the next, which had been increasing in length) begin to decrease, and the growth appears to be thicker. Branches which appeared in the axils of each set of leaves grow and shape the plant to its characteristic form. The vegetative stage is usually completed in the third to fifth months of growth.
Preflowering
This is a quiescent period of one to two weeks during which growth slows considerably. The plant is beginning a new program of growth as encoded in its genes. The old system is turned off and the new program beings with the appearance of the first flowers.
Flowering
Cannabis is dioecious: each plant produces either male or female flowers, and is considered either a male or female plant. Male plants usually start to flowers about one month before the female; however, there is sufficient overlap to ensure pollination. First the upper internodes elongate; in a few days the male flowers appear. The male flowers are quite small, about 1/4 inch, and are pale green, yellow, or red/purple. They develop in dense, drooping clusters (cymes) capable of releasing clouds of pollen dust. Once pollen falls, males lose vigour and soon die.
The female flowers consists of two small (1/4 to 1/2 inch long), fuzzy white stigmas raised in a V sign and attached at the base to an ovule which is contained in a tiny green pod. The pod is formed from modified leaves (bracts and bracteoles) which envelop the developing seed. The female flowers develop tightly together to form dense clusters (racemes) or buds, cones, or colas (in this book, buds). The bloom continues until pollen reaches the flowers, fertilising them and beginning the formation of seeds. Flowering usually lasts about one or two months, but may continue longer when the plants are not pollinated and there is no killing frost.
Seed Set
A fertilised female flower develops a single seed wrapped in the bracts. In thick clusters, they form the seed-filled buds that make up most fine imported marijuana. After pollination, mature, viable seeds take from 10 days to five weeks to develop. When seeds are desired, the plant is harvested when enough seeds have reached full colour. For a fully-seeded plant this often takes place when the plant has stopped growth and is, in fact, dying. During flowering and seed set, various colours may appear. All the plant's energy goes to reproduction and the continuance of its kind. Minerals and nutrients flow from the leaves to the seeds, and the chlorophylls that give the plant its green colour disintegrate. The golds, browns, and reds which appear are from accessory pigments that formerly had been masked by chlorophyll.
Figure 30 THC potency through various growth stages in the male and female
plant
About Plants Generally
Plants use a fundamentally different "life strategy" from animals. Animals are more or less self-contained units that grow and develop to predetermined forms. They use movement and choice of behaviour to deal with the changing environments. Plants are organised more as open systems - the simple physical characteristics of the environment, such as sunlight, water, and temperature, directly control their growth, form, and life cycles. Once the seed sprouts, the plant is rooted in place and time. Since growth is regulated by the environment, development is on accordance with the plant's immediate surroundings. When a balance is struck, the strategy is a success and life flourishes.
Behaviour of a plant is not a matter of choice; it is a fixed response. On a visible level the response more often than not is growth, either a new form of growth, or specialised growth. By directly responding, plant in effect "know," for example, when to sprout, flower, or drop leaves to prepare for winter.
Everyone has seen how a plant turns toward light or can bend upward if it its stem is bent down. The plant turns by growing cells of different length on opposite sides of the stem. This effect turns or right the plant. The stimulus in the first case is light, in the second gravity, but essentially the plant responds by specialised growth. It is the same with almost all facets of a plant's live - growth is modified and controlled by the immediate environment. The influence of light, wind, rainfall, etc., interacts with the plant (its genetic make-up or genotype) to produce the individual plant (phenotype).
The life cycle of Cannabis is usually complete in four to nine months. The actual time depends on variety, but it is regulated by local growing conditions, specifically the photoperiod (length of day vs night). Cannabis is a long-night (or short-day) plant. When exposed to a period of two weeks of long nights - that is, 13 or more hours of continuous darkness each night - the plants respond by flowering. This has important implications, for it allows the grower to control the life cycle of the plant and adapt it to local growing conditions or unique situations. Since you can control flowering, you control maturation and, hence, the age of the plants at harvest.
3.4 PHOTOPERIOD AND FLOWERING
For the marijuana grower the most important plant/environment interaction to understand is the influence of the photoperiod. The photoperiod is the daily number of hours of day (light) vs. night (dark). In nature, long nights signal the plant that winter is coming and that it is time to flowers and produce seeds. As long as the day-length is long, the plants continue vegetative growth. If female flowers do appear, there will only be a few. These flowers will not form the characteristic large clusters or buds. If the days are too short, the plants flowers too soon, and remain small and underdeveloped.
The plant "senses" the longer nights by a direct interaction with light. A flowering hormone is present during all stages of growth. This hormone is sensitive to light and is rendered inactive by even low levels of light. When the dark periods are long enough, the hormones increase to a critical level that triggers the reproductive cycle. Vegetative growth ends and flowering begins.
The natural photoperiod changes with the passing of seasons. In the Northern Hemisphere, the length of daylight is longest on June 21. Day-length gradually decreases until it reaches its shortest duration on December 22. The duration of daylight then begins to increase until the cycle is completed the following June 21. Because the Earth is tilted on its axis to the sun, day-length also depends on position (or latitude) on Earth. As one moves closer to the equator, changes in the photoperiod are less drastic over the course of a year. At the equator (0 degrees altitude) day length lasts about 12.5 hours on June 21 and 11.5 hours on December 22. In Maine (about 45 degrees north), day-length varies between about 16 and nine hours. Near the Arctic Circe on June 21 there is no night. On December 22 the whole day is dark. The longer day-length toward the north prevents marijuana from flowering until later in the season. Over most of the northern half of the country, flowering is often so late that development cannot be completed before the onset of cold weather and heavy frosts.
The actual length of day largely depends on local conditions, such as cloud cover, altitude, and terrain. On a flat Midwest plain, the effective length of day is about 30 minutes longer than sunrise to sunset. In practical terms, it is little help to calculate the photoperiod, but it is important to realise how it affects the plants and how you can use it to you advantage.
Cannabis generally needs about two weeks of successive long nights before the first flowers appear. The photoperiod necessary for flowering will vary slight with (1) the variety, (2) the age of the plant, (3) its sex, and (4) growing conditions.
1. Cannabis varieties originating from more northerly climes (short growing seasons) react to as little as nine hours of night. Most of these are hemp and seed varieties that are acclimated to short growing seasons, such as the weedy hemps of Minnesota or southern Canada. Varieties from more southerly latitudes need longer nights with 11 to 13 hours of darkness. Since most marijuana plants are acclimated to southerly latitudes, they need the longer nights to flower. To be on the safe side, if you give Cannabis plant dark periods of 13 or more hours, each night for two weeks, this should be enough to trigger flowering. 2. The older a plant (the more physiologically developed), the quicker it responds to long nights. Plants five or six months old sometimes form visible flowers after only four long nights. Young marijuana plants (a month or so of age) can take up to four weeks to respond to long nights of 16 hours. 3. Both male and female Cannabis are long-night plants. Both will flower when given about two weeks of long nights. The male plant, however, will often flower fully under very long days (18 hours) and short nights (six hours). Males often flowers at about the same time they would if they were growing in their original environment. For most marijuana plants this occurs during the third to fifth month. 4. Growing conditions affect flowering in many ways (see Chapter 12). Cool temperatures (about 50F) slow down the flowering response. Cool temperatures or generally poor growing conditions affect flowering indirectly. Flower development is slower, and more time is needed to reach full bloom. Under adverse conditions, female buds will not develop to full size.
Applications of Photoperiod
The photoperiod is used to manipulate the plants in two basic ways:
1. By giving long dark periods, you can force plants to flower. 2. By preventing long nights, using artificial light to interrupt the dark period, you can force the plants to continue vegetative growth.
Outdoors
Most marijuana plants cultivated in the United States begin to flower by late August to early October and the plants are harvested from October to November. For farmers in the South, parts of the Midwest, and West Coast, this presents no problem and no special techniques are needed for normal flowering.
In much of the North and high-altitude areas, many varieties will not have time to complete flowering before fall frosts. To force the plants to flower earlier, give them longer night periods. If the plants are in containers, you can simply move them into a darkened area each evening. Plants growing in the ground can be covered with an opaque tarpaulin, black sheet plastic, or double or triple-layers black plastic trash bags. Take advantage of any natural shading because direct sunlight is difficult to screen completely. For instance, if the plants are naturally shaded in the morning hours, cover the plants each evening or night. The next morning you uncover the plants at about eight to nine o'clock. Continue the treatment each day until all the plants are showing flowers. This usually takes two weeks at most, is the plants are well developed (about four months old). For this reason, where the season starts late, it is best to start the plants indoors or in cold frames and transplant outdoors when the weather is mild. This in effect lengthens the local growing season and gives the plants another month or two to develop. By the end of August the plants are physiologically ready to flower; they sometimes do with no manipulation of the photoperiod. More often female plants show a few flowers, but the day-length prevents rapid development to large clusters. The plants seem in limbo - caught between vegetative growth and flowering. The natural day-length at this time of year will not be long enough to reverse the process, so you can discontinue the treatment when you see that the new growth is predominantly flowers.
In areas where frosts are likely to occur by early October, long-night treatments may be the only way you can harvest good-sized flower clusters. These clusters, or buds, are the most potent plant parts and make up the desired harvest. Forcing the plants to flowers early also means development while the weather is warm and the sun is shining strongly. The flower buds will form much faster, larger and reach their peak potency. A good time to start the treatments is early to middle August. This allows the plants at least four weeks of flowering while the weather is mild.
Another reason you may want to do this is to synchronise the life cycle of the plants with the indigenous vegetation. In the northeast and central states, the growing season ends quite early and much of the local vegetation dies back and changes colour. Any marijuana plants stick out like green thumbs, and the crop may get ripped off or busted. Plants treated with long nights during late July will be ready to harvest in September.
Outdoors, growers should always plant several varieties, because some may naturally flower early, even in the northern-most parts of the country. These early-maturing varieties usually come from Mexican, Central Asian, and homegrown sources. By planting several varieties, many of you will be able to find or develop an early-maturing variety after a season or two. This, of course, is an important point, because it eliminates the need for long-night treatments.
Preventing Flowers
Manipulation of the photoperiod can also prevent the plants from flowering until a desired time. For example, in Hawaii the weather is mild enough to grow winter crops. The normal summer crop is harvested anytime from September to mid-November. The winter crop is generally planted from October to December. Because the winter days are so short, the plants flower almost immediately, usually within two month. The plants are harvested in their third or fourth month and yield about 1/4 the yield of summer plants. A large Hawaiian female can yield a pound of buds. Most of the plant's overall size is reached while it is vegetatively growing. By interrupting the night period with light, you can keep these plants vegetatively growing for another month, yielding plants of about twice the size.
The amount of light needed to prevent flowering is quite small (about .03 foot candles95 - on a clear night the full moon is about .01 foot candles). However, each plant mist be illuminated fully, with the light shining over the whole plant. This might be accomplished with either electric light or a strong flashlight. The easiest way is to string incandescent bulbs, keeping them on a timer. The lights need be turned on for only a flash at any time during the night period, from about 9:00 pm to about 3:00 am. The interrupts the long night period to less then nine hours. Start these night treatments each night or two, until you want the plants to flower.
Indoors
Natural Light
Indoors, the growing season lasts all year. The night period is much easier to control. Sometimes people grow plants in their windows for more than a year without any female flowers ever forming. This is because household lamps are turned on sometime at night, illuminating the plants. Under natural light exclusively, indoor plants flower at about the same time they would outdoors (sometime a bit sooner because it is warmer indoors or the plants may be shaded). When plants are well developed and you want them to flower, make sure that no household lamps or nearby street lamps are shining on them. During late fall and winter, the natural day-length is short enough for the plants to flower naturally, if you simply keep off any lights at night that are in the same room as the plants. If you must use light, use the lowest wattage possible, such as a six-watt bulb. (The hormone is also least sensitive to blue light.) Shield the light away from the plants. Or shield the plants from any household light with aluminium foil curtains. Once the flowers are forming clusters, you can discontinue the dark treatments, especially if it is more convenient. However, if it is too soon (when you see only a few random flowers), household lights can reverse the process.
By using natural light, you can grow indoor crops all year. The winter light is weak and the days are short, so it is best to use artificial lights to supplement daylight, as well as to extend the photoperiod. The extra light will increase the growth rate of the plants and hence size and yield. You should allow winter crops to flower during late January or February, using the natural photoperiod to trigger flowering. If you wait until spring, the natural light period will be too long and may prevent flowering.
Artificial Lights
Under artificial light the photoperiod is, of course, any length you wish. The most popular way to grow with artificial lights is the harvest system. Start the plants under long light periods of from 16 to 18 hours daily. After the plants have reached a good size, usually between three and six months, shorten the light cycle to about 12 hours to force flowering.
To decide exactly when to force the plants to flower, let their growth be the determinant. If male plants are showing their flowers, then the females are physiologically ready to flower. Most of the plant's overall height is achieved during vegetative growth. Some varieties, of course, are smaller and grow more slowly than others. Wait until the plants are nearing the limits of the height of the garden or are at least five feet tall. This is large enough to support good flower development and return a good yield. If you turn down the light cycle when the plants are young and small, you'll harvest much less grass because the plants simply can't sustain a large number of flowers.
Some leaf growers prefer a continuous growth system, emphasising leaf growth and a continuous supply of grass. The light cycle is set for 18 to 24 hours a day. This prevents flowering and the plants continue their rapid vegetative growth. Growing shoots and leaves are harvested as used, and plants are removed whenever they lose their vigour and growth has noticeably slowed. New plants are started in their place. In this way, there will be plants at different growth stages, some of which will be in their rapid vegetative growth stage and will be quite potent. Male plants and some females eventually will form flowers, but the females will not form large clusters. People often use this system when the lights are permanently fixed. Small plants are raised up to the lights on tables or boxes. This garden never shuts down and yields a continuous supply of grass.
3.5 INHERENT VARIATIONS IN POTENCY
The potency of a particular marijuana sample will vary because of many factors other then the variety. Many of these have to do with the natural development of the plants and their resin glands. Environmental factors do affect potency but there are large differences in any variety. These inherent factors must be explained before we can talk of factors outside the plant that affect relative potency. Strictly environmental effects are discussed in Chapter 19.
Variations in Potency Within Varieties
There are noticeable differences in THC concentrations between plants of the same variety. Differences are large enough so that you can tall (by smoking) that certain plants are better. This is no news to homegrowers, who often find a particular plant to be outstanding. Five-fold differences in THC concentration have also shown up in research. However, when you consider a whole group of plants of the same variety, they're relatively similar in cannabinoid concentrations. Type II plants are the most variable, with individual plants much higher than other in certain canninbinoids.
Variations by Plant Part
The concentration of cannabinoids depends on the plant part, or more specifically, the concentration and development of resin glands to plant part. The female flower bracts have the highest concentration of resin glands and are usually the most potent plant parts. Seeds and roots have no resin glands. These shoe no more than traces of canninbinoids. Smoke seeds will give you a headache before you can get high. If you got high on seeds, then there were probably enough bracts adhering to the seeds to get you high. {Figure 29 The highest concentration of stalked resin glands forms a cover on the female flower bracts Resin glands beneath cystolith hairs on a leaf petiole}
Here are the potencies, in descending order, of the various plant parts:
1. Female flowering clusters. In practice you don't separate hundreds
of tiny bracts to make a joint. The whole flowering mass (seeds removed),
along with small accompanying leaves, forms the material.
2. Male flower clusters. These vary more in relative potency depending on
the strain (see "Potency by Sex," below).
3. Growing shoots. Before the plants flower, the vegetative shoots (tips)
of the main stem and branches are the most potent plant parts.
4. Leaves (a) that accompany flowers (small);
(b) along branches (medium);
(c) along main stem (large).
Generally, the smaller the leaf is, the more potent it can be.
5. Petioles (leaf stalks). Same order as leaves.
6. Stems. Same order as leaves. The smaller the stem (twig), the
higher the possible concentration of cannabinoids. Stems over 1/16"
in diameter contain only traces of cannabinoids and are not worth
smoking. The small stems that bear the flowers can be quite potent.
7. Seeds and Roots. Contain only traces (less then .01 percent) and
are not worth smoking or extracting.
This order is fairly consistent. The exceptions can be the small leaves that accompany male flowers, which are sometimes more potent than the flowers themselves. The growing shoots are sometimes more potent than the mature female flowers.
Samples of pollen show varying amounts of cannabinoids. Resin glands are found inside the anthers, alongside the developing pollen grains, and form two rows on opposite sides of each anther. Pollen grains are smaller than the heads of large resin glands ({see Plate 7}), and range from 21 to 69 micrometres in diameter21. A small amount of resin contaminates the pollen when glands rupture, but most of the THC in pollen samples comes from gland heads that fall with pollen when the flowers are shaken to collect it. One study, using pollen for the sample, found concentrations of up to 0.96 percent THC, more then enough to get you high79.
Potency by Position on Plant
The potency of marijuana on any plant increases toward the top of the plant, the topmost bud being the most potent. The bottommost leaves on the main stem are the least potent of the useable material. Along branches there is a less steep THC gradient increasing to the growing tip.
The ratios in Table 11 are representative of high-quality marijuana varieties. Plant no. 2 is an exception, with four percent THC in its lower leaves, a figure comparable to high-quality Colombian and Mexican buds in commercial grass.
Table 11 - Relationship of THC Content to Leaf Position (6
Percentage of THC by weight of Leaf from Position on plant
Plant No. 1 (SP-5) NO.2 (SP-5) NO.3 (UNC-335)
Top 6.1 6.9 4.8
Middle 3 5.5 3.1
Bottom 0.8 4 1.5
Ratio (gradient) 8:4:1 1.7:1.4:1 3:2:1
Notice the large difference in the gradients of Plants no. 1 and 2, which are from the same variety (SP-5). Like almost all characteristics of these plants, considerable variation occurs even among sibling. Our experience is that generally the better the quality of the variety, the steeper the gradient: in other words, the bigger the difference between top and bottom leaves. For example, the plants given here are high-quality type I varieties. Plant no. 1 is more typical, with its steep gradient, than no.2, where the gradient is much less pronounced. Lower-quality varieties generally do not have as steep a gradient and the ratios would look more like that of Plant no. 2.
Potency by Sex
Although marijuana lore claimed the female to be the more potent, scientists disclaimed this. But there is some truth to both sides. In fine marijuana varieties, male and female leaves average about the same in cannabinoid concentrations. Either a male or a female individual may have the highest concentration in any particular case. The largest variation is in comparing the flowers. Male flowers may be comparable to the females, or they may not even get you high. It seems that the higher the quality of the grass, the better the male flowers will be. In fine type I plants, male flowering clusters usually approach the potency of the female. In low-quality type III varieties females are usually more potent (20 to 30 percent) than the males.
Type II plants are the most variable, with large differences among individual plants. But the trend is for the females to average about 20 percent high in potency of leaves and flowers.
Table 12 - Relative Potencies of Male and Female Plants (66)
Percentage by Weight (b) of
COUNTRY OF ORIGIN SEX (a) THC CBD (C) TYPE PLANT
Mexico M 3.7 0.86 I
F 3.7 0.35
India M 4.3 0.12 I
F 1.78 0.19
Thailand M 3.2 0.08 I
F 3.2 0.42
India M 0.81 2.1 II
F 1.3 0.89
Pakistan M 1.37 1.24 II
F 0.71 1.5
Turkey M 0.84 2.11 II
F 0.92 1.33
India M 0.15 2.2 III
F 0.12 1.2
Poland M 0.04 0.97 III
F 0.06 1.1
a) M, male (staminate); F, female (pistillate). (b) Of flowering mass
with accompanying leaves. (c) Includes CBC. _
Potency by Age
In general, the longer the life cycle of the plant, the more the concentration of cannabinoids increases, as long as the plant stays health and vigorous. Actually, it is the development of the plant, rather than chronological age, that determines this difference in potency. A plant that is more developed or more mature is generally more potent.
Because you decide when to plant and/or can control the photoperiod, you also control when the plants flowers and, hence, the overall age at maturity. A six-month-old plant will generally be better than a four-month-old plant, both of which are flowering. Plants eight months old will usually be more potent than six-month-old plants. Most indoor growers plan their gardens to be about five to eight months old at harvest. Healthy plants can be extended to about 10 months. Plants older than 10 months often develop abnormally. There is usually a decline in vigour and a loss in potency. But some growers have decorative plants several years old.
Outdoor growers more often simply allow the plants to develop according to the local growing conditions which will govern their development and flowering time. Where the growing season is short, some growers start the plants indoors and transplant when the local growing season begins. This gives the plants a longer growing season.
One reason female plants are considered more potent is because of age. Males often flower in four to five months and die, while the females may continue to a ripe old age of eight or nine months, especially when they are not pollinated.
Potency by Growth Stage
Although then general trend is for the cannabinoid concentration to increase with age, this is not a matter of the simple addition or accumulation of cannabinoids. The concentration of cannabinoids changes with the general metabolic rate of the plant, and can be related to the plant's growth pattern or life cycle. Figure 30 shows a hypothetical curve following the concentration of THC from the upper leaves and growing tips of a male and female plant.
Notice that THC increases immediately with germination and establishment of the seedling, and continues to rise until the plant enters its vegetative stage. At this point, the plant is well-formed, with a sturdy stem, and no longer looks fragile. As the plant;s rate of growth increases, there is a corresponding rise in THC that continues throughout the vegetative stage until a plateau is reached. Before the plateau is reached the arrangement of leaves on the stem (phyllotaxy) changes from opposite to alternate. The plateau is maintained until the plant's rapid growth all but stops and the plant has entered preflowering. By this time, the branches have formed the plant to its characteristic shape. Preflowering lasts about one to two weeks, during which THC concentration falls until the appearance of the first flowers.
For the male plant, preflowering ends with renewed growth. This lengthens the uppermost internodes and the first male flower buds appear. THC immediately increases with the development of the male flower clusters, and reaches its peak when most of the flowers are fully formed and a few are beginning to release pollen. After pollen release, the male normally loses vigour and THC content slowly declining until the plant is cured and stored.
Female plants reach their maximum THC when the plants are in full bloom. Full bloom is when the plant has filled out with well-formed flower clusters, but flowers are still slowly forming. Most of the stigmas will still be white and healthy.
Flowering lasts anywhere from two to 10 weeks, depending on whether the plants are pollinated or not, as well as on variety and the environment. (See Chapter 20 for details.) THC content declines as the formation of new flowers slows and the majority of the stigmas begin to brown. The only changes you may see in the plants are the maturation of the seeds and the loss of green colour in the leaves and flowers. In some cases the plant's apparent resin (its look and feel) increases during the last few weeks of life while the THC concentration is still declining.
You may feel that you should only pick marijuana when the plants are in full bloom, but this is not the case. Think of the garden as a continuous supply of grass. You can never be sure of the fate of your plants. The biggest problem with outdoor growing is that there is a good chance that the plants will be ripped off before you plan to harvest. It is much better to harvest grass during the course of a season, assuring yourself a return for your efforts. For example, during the third month of growth, you could cut back the growing tips, which should be quite potent, often more potent than Figure 30 suggests. This doesn't mean there will be less to harvest at season's end. In fact, the plant will be forced to develop its branches, possible yielding a larger plant.
Common sense tells you that it is always best to test one sample before you harvest. By taking one tip, curing and smoking, you'll know whether it's worthwhile to harvest more at that time or to wait longer. When a tip is about equal to its parents' potency, then definitely harvest more growing tips. This peak high often occurs during the middle to late rapid, vegetative-growth stage.
The reader should keep in mind that Figure 30 serves only as an example. Chronological age is not as important as the physiological age of the plant. In this graph, the life of the plants is about six months. But the life cycle depends on the particular variety and the growing conditions, which strongly influence the rate of development. (For details on how to use the graph, see Chapter 20.) The important facts that the reader should get from the graph are that the potency of the grass can decrease as well as increase during the plant's life cycle. Actual studies of the cyclic variations in potency over the course of a season have shown much more complicated rhythms, with many more peaks and valleys then here 71,74,80,86,92. Most varieties will more or less follow a growth pattern as described. Changes in the plant's development, such as phyllotaxy and growth rate, are cues to changes in THC concentration. Secondly, the growing tips of the main stem and branches can be very potent. Growers do not have to wait until flowers form to harvest top-quality smoke.
3.6 Cultivation: Indoors or Outdoors?
The basic elements of the environment (light, water, air, and soil) provide plants with their fundamental needs. These environmental factors affect the growth rates of plants, as well as their life cycles. If one factor is deficient, growth rate and vigour will wan regardless of the other three. For instance, with low light, the growth will be limited no matter how fertile and moist the soil is. In the same sense, if soil minerals are scarce, the growth rate will be limited no matter how you increase the light.
Photosynthesis
Cannabis, like all green plants, manufacturers its food through the process photosynthesis. Unlike animals, which depend on pre-formed food for survival, plants can use energy from light to form food (carbohydrates) from simple inorganic molecules absorbed from the air and soil.
Plants absorb light energy through pigments that are concentrated in the leaf cells. These pigments are also found in most of the aboveground parts of the plant. The most abundant pigment is chlorophyll, which gives the plants their green colour. The energy absorbed is stored in chemical compounds such as ATP and NADPH2. ((ATP, adenosine-triphosphate; NADPH2, nicotinamide-adenine-dinucleotide-phosphate.)) These are storage/transfer compounds that function to transfer energy and matter in the living system. ATP transfers energy that fuels the reactions for the making of carbohydrates as well as most other metabolic functions. NADPH2 transfers electrons, usually as hydrogen, for the synthesis of carbohydrates as well as other compounds.
The raw material for the synthesis of carbohydrates (CH2O)n comes from carbon dioxide (CO2) and water (H2O). Carbon dioxide is absorbed primarily from the air, but can also be absorbed from the soil and secondarily from the air.
Photosynthesis is summarised as follow:
light energy ------- ATP + NADPH2
CO2 + H2O ------- (CH2O)n + O2
For more complex bio-molecules such as amino acids and proteins, the plant absorbs minerals (including nitrogen, phosphorus, and sulfur) from the soil. Carbohydrates provide food energy for the plant using processes similar to those that occur in humans. They also form the basic building blocks for plant tissues. For example, the sugar glucose (CH2O)6 is strung and bonded to farm long chains of cellulose, the most abundant organic compound on earth. About 80 percent of the structure of the plant's cells is made from cellulose.
The plant is a living thing existing in a holistic world; a myriad of factors affect its life. However, good cultivation techniques require attention to only four basic growth factors. With this accomplished, the plants will do the rest.
As grower, your strategy is to bring out the plant's natural qualities. The cannabinoids are natural to the plants. Seeds from potent marijuana grow into potent marijuana plants when they are nurtured to a full and healthy maturity.
Since most marijuana plants are adapted to tropical or semitropical climates, it is up to the grower to make the transition to local growing conditions harmonious. The requires sensible gardening techniques and, in some cases, manipulation of the photoperiod. There is no magic button to push or secret fertiliser to sue. The secret of potency lies within the embryo. The environment can and does affect potency, as it does most aspects of the plant's life. However, environmental factors are secondary to the plant's heritage (genetic potential).
Indoors vs. Outdoors
At this point the book divides into separate indoor and outdoor cultivation sections, and you may wonder whether it is better to grow the plant indoors or outdoors. Each alternative has advantages and disadvantages. It is usually better to grow the plants outdoors if possible, because the plants can grow much larger and faster than indoors. Indoors presents space and light limitations. It is possible to grow a 15-foot bush indoors, but this is unrealistic in most home. There simply isn't enough room or light for such a large plant. Outdoor gardens return a much higher yield for the effort and expense. most indoor gardeners buy soil and may have to buy electric lights. So there is an initial investment of anywhere from $10 on up.
On the other hand, outdoor plants are more likely to be seen. Many gardens get ripped off, and busts are a constant threat. Indoor gardens are much less likely to be discovered. Gardening indoors allows the grower closer contact with the plants. The plants can be grown all year long; it is an easy matter to control their growth cycles and flowering. Probably the biggest attraction of indoor gardens is that they are beautiful to watch and easy to set up anywhere.
One popular compromise is to construct a simple greenhouse. Use plastic to either enclose part of a porch or to cover a frame built against the house.
The potency of the plants doesn't depend on whether they are grown indoors or outdoors. As long as you grow healthy plants that reach maturity and complete their life cycle, the grass can be as good as any you've ever smoked.
