patchwayraver
Active Member
How To Breed Marijuana Plants
It is possible to breed and select cuttings from plants that grow, flower, and mature faster. Some plants will naturally be better than others in this regard, and it is easy to select not only the most potent plants to clone or breed, but the fastest growing/flowering plants as well.
Find your fastest growing female plant, and breed it with your best high male for fast flowering, potent strains. Clone your fastest, best high female plant for the quickest single crop garden possible. Over time, it will save you a lot of waiting around for your plants to mature.
When a male is starting to flower (usually 1-2 weeks before the females) it should be removed from the females so it does not pollinate them. Any place that gets just a few hours of sunlight per day will be adequate. Supply male plants with the proper growing conditions, and place newspaper or glass to catch the pollen that the flowers release.
Save pollen in an air tight bag and put it in the freezer. It will be good for about a month. It may be several more weeks before the females are ready to pollinate. Put a dry paper towel in the bag with it to absorb moisture.
A female plant is ready to pollinate 2 weeks after the clusters of flowers first appear. If you pollinate too early, it may not work. Wait until the female flowers are well established, but when the hairs are still white (before they turn red/brown).
Turn off all fans. Use a paper bag to pollinate a branch of a female plant. Use different pollen from two males on separate branches. Wrap the bag around the branch and seal it at the opening to the branch. Shake the branch vigorously. After a few minutes, carefully remove the bag.
Large plastic zip-lock bags can be used also. Slip the bag over the male branch and shake the pollen loose. Carefully remove the bag and zip it up. It should be very dusty with pollen. To pollinate, place it over a single branch of the female, placing it so no pollen leaks out.
Shake the bag and the stem at the same time. Allow to settle for an hour or two and shake it again. Remove the bag a few hours later. Your branch is now well pollinated and should show signs of visible seed production in 2 weeks. One pollinated branch can create hundreds of seeds, so it should not be necessary to pollinate more than one or two branches in most cases.
When crossing two different strains, a third strain of marijuana plant will be created. If you know what characteristics you're looking for in a new strain, you will need several plants to choose from in order to have the best chance of finding all the qualities desired.
Sometimes, if the two plants bred had dominant genes for certain characteristics, it will be impossible to get the plant you want from one single cross. In this case, it is necessary to interbreed two plants from the same batch of resultant seeds from the initial cross. In this fashion, recessive genes will become available, and the plant character you desire may only be possible in this manner.
Usually, it is desirable only to cross two strains that are very different. In this manner, one usually arrives at what is referred to as hybrid vigor. In other words, often the best strains are created by taking two very different strains and mating them. Less robust plants may be the result of interbreeding, since it opens up recessive gene traits that may lead to reduced potency.
Hybrid offspring will all be very different from each other. Each plant grown from the same batch of seeds collected from the same plant, will be different. It is then necessary to try each plant separately and decide it's individual merits for yourself. If you find one that seems to be head and shoulders above the rest in terms of early flowering, high yield, and high, that is the plant to clone and continue breeding.
In depth genetics is beyond the scope of this work. Get a copy of the cannabis breeder's bible and/or marijuana botany, for more detailed info in this area.
Carbon Dioxide (CO2): Marijuana plants use CO2 when the light is on, so you will have to provide them with a constant fresh supply. In a room with no air circulation, plants will use the available carbon dioxide in a few hours.
When CO2 levels fall, plant growth slows. Letting in air through a window, door, or other means (and keeping it circulating with a fan) will be necessary.
Carbon Dioxide is measured in parts per million (ppm). The ideal CO2 level for marijuana plants is near 700 ppm. Some advanced growers increase the amount of CO2 to the grow area so the plants have a steady concentration of about 700 ppm.
An optimal amount of CO2 will increase the growth rate of the marijuana plant. Although this does not mean a more potent crop, it will produce a larger harvest in less time than a crop raised with less CO2.
Adding carbon dioxide to a grow room is not something for the beginner to experiment with unless you have a cheap and easily obtainable supply with a means of measuring it. Here are some CO2 levels and how they affect plant growth.
200 ppm (Plant Growth Slows)
300 ppm (Outside Air)
700 ppm (Ideal For Marijuana)
2000 ppm (Plants Burn)
5000 ppm (Plants Die)
If you vent the air out of a grow room with an exhaust system that removes air from a grow room, most (or all) of the CO2 will be removed from the grow area before the plants can use it. An air cooled lighting system that takes in and exhausts the air from places other than the grow room is suggested when CO2 is being used.
EC, TDS, PPM, CF:
EC stands for Electrical Conductivity. It is measured in mS/cm (miliSiemens per centimeter). It is method of measuring the amount of dissolved solids in nutrient solution.
TDS stands for Total Dissolved Solids. It is measured in PPM (parts per million). It is also a method of measuring the amount of dissolved solids in nutrient solution.
EC meters and TDS meters are both used to determine the strength of the hydroponic solution. Making sure the nutrient solution is optimal would be something intermediate and advanced hydroponic marijuana growers would want to monitor.
If you are a first time or beginning grower, this is not as important as the pH level and temperature. After you raise a few crops you will probably want to provide the ideal growing conditions for maximum potency and yield. Measuring the amount of dissolved solids in nutrient solution and keeping them within the proper range will be something to work on.
In my case, a good EC meter reading (for the marijuana strains that have been grown) has been about 0.7 to 1.5 mS during the vegetative phase and 1.0 to 2.0 mS during the flowering phase. You can increase the EC meter reading by adding more nutrients to the nutrient reservoir. You can decrease the EC meter reading by diluting the nutrients in the reservoir with more water.
A good TDS meter reading for marijuana during the vegetative phase is about 450 to 1000 PPM. During flowering a good TDS meter reading would be about 700 to 1500 ppm. You can increase the PPM value by adding more nutrients to the nutrient reservoir. You can decrease the PPM value by diluting the nutrients in the reservoir with more water.
These values work for me but the numbers that are optimal for your setup may vary somewhat depending on pH level, temperature, seed strain, etc. Take EC and TDS readings after nutrients have been added to the reservoir, then check every few days.
Some strains need more nutrients than others, start by aiming towards EC and TDS readings on the low side of the scale and work up slowly. Optimal amounts will vary with the strain so experiment but keep within the limits mentioned above.
If you are going to get a meter to measure the amount of dissolved solids in your hydroponic nutrient solution, get an EC meter rather than a TDS meter. EC meters are more accurate than TDS meters.
A CF meter uses CF (Conductivity Factor) scale. This is simply the EC scale multiplied by ten (1 mS = 10 CF). To find the EC with a CF meter just divide the CF meter reading by ten
(10 CF = 1 mS).
Heat: Grow lights get hot and heat can be a problem. The more watts of light you use, the more heat those lights generate. Even 250 watt lights can heat a small area beyond acceptable limits. If the temperature gets too hot it could have a negative effect on the plants by slowing down growth or killing them.
Some growers use an air conditioner to cool the air, others prefer to vent hot air from the ceiling into another room, attic, or outside through the chimney, roof, or wall. Your local hardware store should have some kind of exhaust system. I've seen bathroom fan, dryer vent, and other similar systems adapted to serve this purpose. There are also air cooled lighting systems to remove heat produced by lights before the air can affect the grow area.
If you are using more than 250 watts of lighting, you will probably have to use an exhaust system. If not, you will need a large air conditioner that will run constantly. Your electric bills will be very high. Large commercial operations use industrial exhaust fans that cost several hundred dollars each. An exhaust system should be able to move a volume of air equal to the room size every 3-5 minutes.
Humidity: Use a hydrometer to measure humidity if you think your grow area is out of range. A humidifier can increase humidity and a dehumidifier can be used to lower humidity. In general readings between 40-60 percent relative humidity are recommended.
The humidity should always be kept below 60% to minimize the chances of mold development. If mold is a problem in your grow room, humidity should always be kept below 50%.
Media: Since you aren't using soil in a hydroponic garden, some types of hydroponic gardens (deep water culture, drip systems, ebb and flow systems, wick systems) need a substitute so the roots have somewhere to anchor the plant.
This substitute for soil is referred to as growing medium or media. The media will provide no nutrition, it is just a support for the roots. All nutrition comes from the nutrient solution.
There are various types of media available to grow hydroponic marijuana in. Rockwool is one common type of media, but there are others. Rockwool comes in blocks of solid material that are very similar in feel and appearance to fiberglass insulation used in housebuilding.
There are some types of media that are made up of loose particles like soil. Stay away from these unless your hydroponic garden is designed to use this type of media. Particles can drain into the nutrient reservoir and eventually ruin the pump.
The media you use is up to you. Follow what the manufacturer of your hydroponic garden recommends. If you aren't sure, get rockwool (also known as mineral wool), horticube (for seeds and clones, also known as oasis cubes), or another solid type of media. You can buy some types of growing media in slabs that can be cut to fit into your garden or you can get it in various pre-cut sizes.
There are also small rockwool and oasis cubes designed for starting clones or seeds on. You can germinate seeds right on these. Once you've grown a crop or two you can experiment and see if changing media has any effect.
Rockwool and some other types of media should be soaked in water overnight before use. Sometimes this should be water of a certain pH. This is to ensure that the rockwool has a neutral pH level. Follow the manufacturers directions.
If there are no directions, soak the rockwool (overnight) in a clean pot or container with water that has been pH adjusted to 5.5. Next day, discard the water, and fill the pot or container with hot water (pH adjusted to 6.0) to kill any unwanted organisms that might have a negative effect on your plants.
After a minimum of ten minutes in the water, you can drain the container and wait for the rockwool to cool to room temperature. Once cool, the rockwool is ready for use. It isn't necessary to treat the media with hot water but if you are worried about being clean, give it a try.
Number Of Plants: In many areas, drug trafficking charges are determined by the number of plants being grown. In these areas a plant that produces two ounces (about 56 grams) at harvest time is considered the same as a plant that produces one-eighth of an ounce (about 3.5 grams) at harvest time.
Even if you had a permit to produce medical marijuana for yourself, once you grow more than a set number of plants in certain jurisdictions, you are considered to be cultivating with intent to traffic. So growing 10-20 fairly large plants that will produce an ounce (or more) per plant might be a better idea than growing 40-80 smaller plants that will produce a quarter ounce per plant.
Nutrients: See the page about nutrients and growing hydroponic marijuana to find out how nutrients affect marijuana plant growth.
Odors: Growing (and smoking) marijuana will produce odors. Sometimes they can be strong enough to attract attention of people who don't need to know what you are doing. If you would like to eliminate the smell from growing and/or smoking marijuana the best thing to do is use ozone.
An alternative method is to use exhaust fans, these have the advantage of also being used to remove heat from the grow room. If you plan on using an exhaust system, make sure it is vented to an area that won't attract attention. Placing the exhaust end on a roof or other space that is seldom used by other people is a good idea.
pH: The pH of the nutrient solution should be somewhere in between 5.5 and 6.8 on the pH scale. You will need a pH meter or pH test kit to check the pH and some pH up-down solution to adjust the pH when it gets out of range. See the page about pH and marijuana if you would like to learn more.
Temperature: Aim for between 70-80 degrees F when the light is on. When the light is off the temperature can drop 10-15 degrees without harming the plants. The temperature should never go very much below 60 degrees or above 90 degrees (even for short periods) or growth will slow down. If these extremes are exceeded for an extended amount of time, the plant may be permanently damaged or killed.
Every strain has an optimal day temperature and an optimal night temperature. The closer you get to the optimal temperature of the marijuana strain you are growing, the better your plants will grow. Strains that originated in cool areas prefer a lower temperature than strains that originated in warm areas.
Some strains might like temperatures outside of the 70-80 degree range but most will do best somewhere in between 72-75 degrees. Plants grown with supplemental carbon dioxide prefer temperatures around 80-85 degrees.
Two Growing Areas: An alternative to growing in one area with mh and hps lighting is to set up separate vegetative and a flowering areas.
The vegetative area would use a cloner or something similar that would allow seeds or clones to grow. Light would be supplied by two standard 24 inch or 48 inch fluorescent bulbs (or more), turned on 20-24 hours a day. Use 30-60 watt (40 watt bulbs are recommended) cool white fluorescent tubes.
A cloner is a hydroponic based growing unit designed for growing small plants. The openings to place the plants in are close together, so more plants can grow in a small area. When the plants have grown large enough, they are moved to the flowering area.
The flowering area would use a standard hydroponic set up with hps and/or mh fixtures turned on for 12 hours a day. While the flowering plants are going through their cycle, the germinated seeds or clones will have a 8 to 10 weeks to develop in the cloner.
After the flowering plants have been harvested, the plants in the vegetative area are ready to move to the flowering area. New seedlings or clones can then be started in the cloner.
There are three main benefits to this kind of set up. Electricity use will be about 20% to 35% less because the mh or hps light is only on 12 hours a day. The longer a plant has been growing in the vegetative phase, the quicker it will flower.
And you will be able to produce more marijuana because you will harvest about once every 8 to 10 weeks, rather than only being able to harvest about once every 12 to 16 weeks with a single growing area.
The only drawback I have found is the extra area needed to set up two different grow areas. Since the flowering plants need absolute darkness during the dark phase, the light from the vegetative area can't reach the flowering plants.
These areas will have need to be isolated from each other and other sources of light either by using curtains (or something similar) or by being located away from each other.
Any available sunlight will help in the growing process. The vegetative area can be open to extra light at all times but there must be a way to block out all sources of light for twelve hours a day in the flowering area.
----- A plant will die if the roots dry out. Check everyday (or more often) and make sure that the nutrient solution is being circulated properly. Drip systems and ebb and flow systems can keep a plant alive for up to a day (sometimes longer) if the nutrient supply is stopped. A plant in an NFT systems will die within hours of the nutrient solution being stopped and a plant in an aeroponic system probably won't last an hour.
Deep water culture is based on the roots being in the same reservoir as the nutrient solution. There is no chance of the roots drying out unless the reservoir isn't filled. However, the roots must be supplied with oxygen (usually supplied with an air pump). If this supply of oxygen is stopped, the plants will die in several days.
----- Do not use chemicals to clean anything that the water and nutrients will come into contact with, like the inside of nutrient reservoir or hydroponic garden. Use hot water to clean these.
----- Never touch a metal halide or high pressure sodium bulb with your hands. Body oils will shorten the life of the bulb. If you do touch a bulb, wash it off with a clean cloth that has been dampened with water. Wait till the bulb is dry before using, water can cause the bulb to crack. A lit (or hot) bulb can crack or explode if it comes in contact with liquids like water.
----- You can only use a bulb of the wattage you light system was designed for. A 400 watt system only uses 400 watt bulbs. Don't use any other wattage than the one listed on the ballast of your light system.
----- You can use hydroponics to grow outdoors but temperatures must remain within the tolerance of the plant. That means in most parts of the world, you would only be able to grow for several months of the year. Temperatures must also remain higher than the freezing point of water. Evaporation of nutrient solution can also be a problem.
----- When you enter the growing environment. You should be as clean as possible. Taking a shower and changing clothes prior to entering would be a good idea but time consuming. Try to at least wash your face and hands and have clean clothes on prior to entry. This will minimize the chance of contamination.
It is possible to breed and select cuttings from plants that grow, flower, and mature faster. Some plants will naturally be better than others in this regard, and it is easy to select not only the most potent plants to clone or breed, but the fastest growing/flowering plants as well.
Find your fastest growing female plant, and breed it with your best high male for fast flowering, potent strains. Clone your fastest, best high female plant for the quickest single crop garden possible. Over time, it will save you a lot of waiting around for your plants to mature.
When a male is starting to flower (usually 1-2 weeks before the females) it should be removed from the females so it does not pollinate them. Any place that gets just a few hours of sunlight per day will be adequate. Supply male plants with the proper growing conditions, and place newspaper or glass to catch the pollen that the flowers release.
Save pollen in an air tight bag and put it in the freezer. It will be good for about a month. It may be several more weeks before the females are ready to pollinate. Put a dry paper towel in the bag with it to absorb moisture.
A female plant is ready to pollinate 2 weeks after the clusters of flowers first appear. If you pollinate too early, it may not work. Wait until the female flowers are well established, but when the hairs are still white (before they turn red/brown).
Turn off all fans. Use a paper bag to pollinate a branch of a female plant. Use different pollen from two males on separate branches. Wrap the bag around the branch and seal it at the opening to the branch. Shake the branch vigorously. After a few minutes, carefully remove the bag.
Large plastic zip-lock bags can be used also. Slip the bag over the male branch and shake the pollen loose. Carefully remove the bag and zip it up. It should be very dusty with pollen. To pollinate, place it over a single branch of the female, placing it so no pollen leaks out.
Shake the bag and the stem at the same time. Allow to settle for an hour or two and shake it again. Remove the bag a few hours later. Your branch is now well pollinated and should show signs of visible seed production in 2 weeks. One pollinated branch can create hundreds of seeds, so it should not be necessary to pollinate more than one or two branches in most cases.
When crossing two different strains, a third strain of marijuana plant will be created. If you know what characteristics you're looking for in a new strain, you will need several plants to choose from in order to have the best chance of finding all the qualities desired.
Sometimes, if the two plants bred had dominant genes for certain characteristics, it will be impossible to get the plant you want from one single cross. In this case, it is necessary to interbreed two plants from the same batch of resultant seeds from the initial cross. In this fashion, recessive genes will become available, and the plant character you desire may only be possible in this manner.
Usually, it is desirable only to cross two strains that are very different. In this manner, one usually arrives at what is referred to as hybrid vigor. In other words, often the best strains are created by taking two very different strains and mating them. Less robust plants may be the result of interbreeding, since it opens up recessive gene traits that may lead to reduced potency.
Hybrid offspring will all be very different from each other. Each plant grown from the same batch of seeds collected from the same plant, will be different. It is then necessary to try each plant separately and decide it's individual merits for yourself. If you find one that seems to be head and shoulders above the rest in terms of early flowering, high yield, and high, that is the plant to clone and continue breeding.
In depth genetics is beyond the scope of this work. Get a copy of the cannabis breeder's bible and/or marijuana botany, for more detailed info in this area.
Carbon Dioxide (CO2): Marijuana plants use CO2 when the light is on, so you will have to provide them with a constant fresh supply. In a room with no air circulation, plants will use the available carbon dioxide in a few hours.
When CO2 levels fall, plant growth slows. Letting in air through a window, door, or other means (and keeping it circulating with a fan) will be necessary.
Carbon Dioxide is measured in parts per million (ppm). The ideal CO2 level for marijuana plants is near 700 ppm. Some advanced growers increase the amount of CO2 to the grow area so the plants have a steady concentration of about 700 ppm.
An optimal amount of CO2 will increase the growth rate of the marijuana plant. Although this does not mean a more potent crop, it will produce a larger harvest in less time than a crop raised with less CO2.
Adding carbon dioxide to a grow room is not something for the beginner to experiment with unless you have a cheap and easily obtainable supply with a means of measuring it. Here are some CO2 levels and how they affect plant growth.
200 ppm (Plant Growth Slows)
300 ppm (Outside Air)
700 ppm (Ideal For Marijuana)
2000 ppm (Plants Burn)
5000 ppm (Plants Die)
If you vent the air out of a grow room with an exhaust system that removes air from a grow room, most (or all) of the CO2 will be removed from the grow area before the plants can use it. An air cooled lighting system that takes in and exhausts the air from places other than the grow room is suggested when CO2 is being used.
EC, TDS, PPM, CF:
EC stands for Electrical Conductivity. It is measured in mS/cm (miliSiemens per centimeter). It is method of measuring the amount of dissolved solids in nutrient solution.
TDS stands for Total Dissolved Solids. It is measured in PPM (parts per million). It is also a method of measuring the amount of dissolved solids in nutrient solution.
EC meters and TDS meters are both used to determine the strength of the hydroponic solution. Making sure the nutrient solution is optimal would be something intermediate and advanced hydroponic marijuana growers would want to monitor.
If you are a first time or beginning grower, this is not as important as the pH level and temperature. After you raise a few crops you will probably want to provide the ideal growing conditions for maximum potency and yield. Measuring the amount of dissolved solids in nutrient solution and keeping them within the proper range will be something to work on.
In my case, a good EC meter reading (for the marijuana strains that have been grown) has been about 0.7 to 1.5 mS during the vegetative phase and 1.0 to 2.0 mS during the flowering phase. You can increase the EC meter reading by adding more nutrients to the nutrient reservoir. You can decrease the EC meter reading by diluting the nutrients in the reservoir with more water.
A good TDS meter reading for marijuana during the vegetative phase is about 450 to 1000 PPM. During flowering a good TDS meter reading would be about 700 to 1500 ppm. You can increase the PPM value by adding more nutrients to the nutrient reservoir. You can decrease the PPM value by diluting the nutrients in the reservoir with more water.
These values work for me but the numbers that are optimal for your setup may vary somewhat depending on pH level, temperature, seed strain, etc. Take EC and TDS readings after nutrients have been added to the reservoir, then check every few days.
Some strains need more nutrients than others, start by aiming towards EC and TDS readings on the low side of the scale and work up slowly. Optimal amounts will vary with the strain so experiment but keep within the limits mentioned above.
If you are going to get a meter to measure the amount of dissolved solids in your hydroponic nutrient solution, get an EC meter rather than a TDS meter. EC meters are more accurate than TDS meters.
A CF meter uses CF (Conductivity Factor) scale. This is simply the EC scale multiplied by ten (1 mS = 10 CF). To find the EC with a CF meter just divide the CF meter reading by ten
(10 CF = 1 mS).
Heat: Grow lights get hot and heat can be a problem. The more watts of light you use, the more heat those lights generate. Even 250 watt lights can heat a small area beyond acceptable limits. If the temperature gets too hot it could have a negative effect on the plants by slowing down growth or killing them.
Some growers use an air conditioner to cool the air, others prefer to vent hot air from the ceiling into another room, attic, or outside through the chimney, roof, or wall. Your local hardware store should have some kind of exhaust system. I've seen bathroom fan, dryer vent, and other similar systems adapted to serve this purpose. There are also air cooled lighting systems to remove heat produced by lights before the air can affect the grow area.
If you are using more than 250 watts of lighting, you will probably have to use an exhaust system. If not, you will need a large air conditioner that will run constantly. Your electric bills will be very high. Large commercial operations use industrial exhaust fans that cost several hundred dollars each. An exhaust system should be able to move a volume of air equal to the room size every 3-5 minutes.
Humidity: Use a hydrometer to measure humidity if you think your grow area is out of range. A humidifier can increase humidity and a dehumidifier can be used to lower humidity. In general readings between 40-60 percent relative humidity are recommended.
The humidity should always be kept below 60% to minimize the chances of mold development. If mold is a problem in your grow room, humidity should always be kept below 50%.
Media: Since you aren't using soil in a hydroponic garden, some types of hydroponic gardens (deep water culture, drip systems, ebb and flow systems, wick systems) need a substitute so the roots have somewhere to anchor the plant.
This substitute for soil is referred to as growing medium or media. The media will provide no nutrition, it is just a support for the roots. All nutrition comes from the nutrient solution.
There are various types of media available to grow hydroponic marijuana in. Rockwool is one common type of media, but there are others. Rockwool comes in blocks of solid material that are very similar in feel and appearance to fiberglass insulation used in housebuilding.
There are some types of media that are made up of loose particles like soil. Stay away from these unless your hydroponic garden is designed to use this type of media. Particles can drain into the nutrient reservoir and eventually ruin the pump.
The media you use is up to you. Follow what the manufacturer of your hydroponic garden recommends. If you aren't sure, get rockwool (also known as mineral wool), horticube (for seeds and clones, also known as oasis cubes), or another solid type of media. You can buy some types of growing media in slabs that can be cut to fit into your garden or you can get it in various pre-cut sizes.
There are also small rockwool and oasis cubes designed for starting clones or seeds on. You can germinate seeds right on these. Once you've grown a crop or two you can experiment and see if changing media has any effect.
Rockwool and some other types of media should be soaked in water overnight before use. Sometimes this should be water of a certain pH. This is to ensure that the rockwool has a neutral pH level. Follow the manufacturers directions.
If there are no directions, soak the rockwool (overnight) in a clean pot or container with water that has been pH adjusted to 5.5. Next day, discard the water, and fill the pot or container with hot water (pH adjusted to 6.0) to kill any unwanted organisms that might have a negative effect on your plants.
After a minimum of ten minutes in the water, you can drain the container and wait for the rockwool to cool to room temperature. Once cool, the rockwool is ready for use. It isn't necessary to treat the media with hot water but if you are worried about being clean, give it a try.
Number Of Plants: In many areas, drug trafficking charges are determined by the number of plants being grown. In these areas a plant that produces two ounces (about 56 grams) at harvest time is considered the same as a plant that produces one-eighth of an ounce (about 3.5 grams) at harvest time.
Even if you had a permit to produce medical marijuana for yourself, once you grow more than a set number of plants in certain jurisdictions, you are considered to be cultivating with intent to traffic. So growing 10-20 fairly large plants that will produce an ounce (or more) per plant might be a better idea than growing 40-80 smaller plants that will produce a quarter ounce per plant.
Nutrients: See the page about nutrients and growing hydroponic marijuana to find out how nutrients affect marijuana plant growth.
Odors: Growing (and smoking) marijuana will produce odors. Sometimes they can be strong enough to attract attention of people who don't need to know what you are doing. If you would like to eliminate the smell from growing and/or smoking marijuana the best thing to do is use ozone.
An alternative method is to use exhaust fans, these have the advantage of also being used to remove heat from the grow room. If you plan on using an exhaust system, make sure it is vented to an area that won't attract attention. Placing the exhaust end on a roof or other space that is seldom used by other people is a good idea.
pH: The pH of the nutrient solution should be somewhere in between 5.5 and 6.8 on the pH scale. You will need a pH meter or pH test kit to check the pH and some pH up-down solution to adjust the pH when it gets out of range. See the page about pH and marijuana if you would like to learn more.
Temperature: Aim for between 70-80 degrees F when the light is on. When the light is off the temperature can drop 10-15 degrees without harming the plants. The temperature should never go very much below 60 degrees or above 90 degrees (even for short periods) or growth will slow down. If these extremes are exceeded for an extended amount of time, the plant may be permanently damaged or killed.
Every strain has an optimal day temperature and an optimal night temperature. The closer you get to the optimal temperature of the marijuana strain you are growing, the better your plants will grow. Strains that originated in cool areas prefer a lower temperature than strains that originated in warm areas.
Some strains might like temperatures outside of the 70-80 degree range but most will do best somewhere in between 72-75 degrees. Plants grown with supplemental carbon dioxide prefer temperatures around 80-85 degrees.
Two Growing Areas: An alternative to growing in one area with mh and hps lighting is to set up separate vegetative and a flowering areas.
The vegetative area would use a cloner or something similar that would allow seeds or clones to grow. Light would be supplied by two standard 24 inch or 48 inch fluorescent bulbs (or more), turned on 20-24 hours a day. Use 30-60 watt (40 watt bulbs are recommended) cool white fluorescent tubes.
A cloner is a hydroponic based growing unit designed for growing small plants. The openings to place the plants in are close together, so more plants can grow in a small area. When the plants have grown large enough, they are moved to the flowering area.
The flowering area would use a standard hydroponic set up with hps and/or mh fixtures turned on for 12 hours a day. While the flowering plants are going through their cycle, the germinated seeds or clones will have a 8 to 10 weeks to develop in the cloner.
After the flowering plants have been harvested, the plants in the vegetative area are ready to move to the flowering area. New seedlings or clones can then be started in the cloner.
There are three main benefits to this kind of set up. Electricity use will be about 20% to 35% less because the mh or hps light is only on 12 hours a day. The longer a plant has been growing in the vegetative phase, the quicker it will flower.
And you will be able to produce more marijuana because you will harvest about once every 8 to 10 weeks, rather than only being able to harvest about once every 12 to 16 weeks with a single growing area.
The only drawback I have found is the extra area needed to set up two different grow areas. Since the flowering plants need absolute darkness during the dark phase, the light from the vegetative area can't reach the flowering plants.
These areas will have need to be isolated from each other and other sources of light either by using curtains (or something similar) or by being located away from each other.
Any available sunlight will help in the growing process. The vegetative area can be open to extra light at all times but there must be a way to block out all sources of light for twelve hours a day in the flowering area.
----- A plant will die if the roots dry out. Check everyday (or more often) and make sure that the nutrient solution is being circulated properly. Drip systems and ebb and flow systems can keep a plant alive for up to a day (sometimes longer) if the nutrient supply is stopped. A plant in an NFT systems will die within hours of the nutrient solution being stopped and a plant in an aeroponic system probably won't last an hour.
Deep water culture is based on the roots being in the same reservoir as the nutrient solution. There is no chance of the roots drying out unless the reservoir isn't filled. However, the roots must be supplied with oxygen (usually supplied with an air pump). If this supply of oxygen is stopped, the plants will die in several days.
----- Do not use chemicals to clean anything that the water and nutrients will come into contact with, like the inside of nutrient reservoir or hydroponic garden. Use hot water to clean these.
----- Never touch a metal halide or high pressure sodium bulb with your hands. Body oils will shorten the life of the bulb. If you do touch a bulb, wash it off with a clean cloth that has been dampened with water. Wait till the bulb is dry before using, water can cause the bulb to crack. A lit (or hot) bulb can crack or explode if it comes in contact with liquids like water.
----- You can only use a bulb of the wattage you light system was designed for. A 400 watt system only uses 400 watt bulbs. Don't use any other wattage than the one listed on the ballast of your light system.
----- You can use hydroponics to grow outdoors but temperatures must remain within the tolerance of the plant. That means in most parts of the world, you would only be able to grow for several months of the year. Temperatures must also remain higher than the freezing point of water. Evaporation of nutrient solution can also be a problem.
----- When you enter the growing environment. You should be as clean as possible. Taking a shower and changing clothes prior to entering would be a good idea but time consuming. Try to at least wash your face and hands and have clean clothes on prior to entry. This will minimize the chance of contamination.