Most people assume pH control is essential, but there is considerable misunderstanding about the effect of pH on plant growth. Plants grow equally well between pH 4 and 7, if nutrients do not become limiting. This is because the direct effects of pH on root growth are small, the problem is reduced nutrient availability at high and low pH. The recommended pH for hydroponic culture is between 5.5 to 5.8 because overall availability of nutrients is optimized at a slightly acid pH. The availabilities of Mn, Cu, Zn and especially Fe are reduced at higher pH, and there is a small decrease in availability of P, K, Ca, Mg at lower pH. Reduced availability means reduced nutrient uptake, but not necessarily nutrient deficiency. The same rule applies to soil.
Instead of water that is high in ph "Calcium" can be used to control the pH.
Most potting soils come with a balanced NPK ratio that will sustain a plant for the first 2-3 weeks. However, as the plant grows taller and wider, supplemental nutrients are required.
In the vegetative stage, a good 20 - 20 - 20 supplement is often adequate to maintain proper growth and development. Most growers dilute this formula to one-half or one-quarter strength, as marijuana does not tolerate full-strength nutrient feedings well. This can be given once or twice a week, although some growers use it at every feeding.
In the flowering stage, a higher ratio of phosphorus is needed to promote and encourage flowering, as these flowers are the bud sites, and the number of flowers affect the end yield. Phosphorus alone, or phosphorus in a higher ratio - 10 - 30 - 10, is often used in this stage.
Secondary foods that the marijuana plants need are calcium, sulphur, and magnesium. These foods ensure that plant photosynthesis is maintained, allowing strong growth and good development.
The trace minerals a plant needs are boron, copper, molybdenum, zinc, iron and manganese. The marijuana plant takes up a minimal amount of these elements, but they are essential to the overall well-being of the plant.
All these nutrients work together to maintain healthy growth and development. Plants will grow poorly or not at all if deprived of any one of these nutrients. If the lack is severe, the plant may go into nutrient lockout, which is the lack of one nutrients blocking the uptake of all the rest, thus causing the plant to die.
Careful, occasional assessment of your plant will determine whether it is healthy and stable, or lacking in any of these nutrients. These problems are easily fixed, but correcting them is very essential to the continued growth and development of your plant.
Calcium is not added to the soil as a nutrient, but rather to balance the pH of the soil.
To grow to a large size, marijuana requires a steady supply of nutrients, which should be added to the water on a regular basis.
The amount of nutrients to add to the water depends on the size of the plant, the size of the pot, and the general condition of the soil.
Always add water when you add any nutrients or fertilizer to the soil.
It is recommended that you dissolve the fertilizer in the water before watering the plant.
Soilless mixtures are a good alternative to using large amounts of soil, the main advantage being that the nutrient balance is easy to control
Continued use of Nitrogen, Phosphorus and Potassium will lower the pH of the soil, this can be rectified by adding some Calcium.
Although healthy, strong growing plants love a steady supply of nutrients, you should never fertilize them every day.
Sorry for the abundance of information...but the basics are very important when it comes to growing good quality bud.
If you have any questions let me know.
