Fertilizing the marijuana plant is different than feeding it. Feeding provides it with basic nutrients needed in order for it to live, while fertilizers make it grow bountifully and give consistently high yields.
Commercial gardening fertilizers come in different ratios of N-P-K. Used at different stages of growth, these will make the plant grow stronger and sturdier, as well as more productive. 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.
Dolomite lime is a long - time farmers` favorite. Lime is essential to maintaining the proper soil pH. Calcium is also commonly used to control soil pH.
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.
Once the cannabis plant is big enough to mature 12" or higher, dark periods must be introduced to start flowering and produce buds. You can bud or flower marijuana by starting dark cycles of about 12/12 hours to simulate oncoming fall as the days grow shorter. The only requirement is to keep the darkness period for flowering very dark with no light interruptions, as this can stall or slow flowering by days or weeks. At most fullmoon light is allowed. Usually growers put lamps on a timer, to create regular and timely dark periods. A few tips: 13 hours of light combined with 11 hours of darkness will increase flower size, but still allow the plant to go into the flowering.
It is advised that you stop using your cannabis flowering fertilizer 2 weeks before harvest time to ensure that all chemicals are out of the plant. If chemicals are in the plant when you harvest, the smoke will be very harsh. To prevent harshness, flush the plants heavily with fresh water 2 weeks prior to harvesting them. Ensure you flush at least 3 times the capacity of your pot. So a 4 gallon pot would be flushed with 16 gallons of distilled water. From that point water your plants with pure water, absolutely NO additives should be given to the plant. This is especially important if you have been using chemical fertilizers.
Pot that has been fertilized right up to harvest is harsh to smoke, sometimes the joint will even sizzle and pop as unmetabolized fertilizer salts combust. Unflushed pot leaves black ash, is hard to keep lit and burns your throat. Pot which has been organically grown and properly flushed is more flavorful and fragrant, burns easily, leaves grey ash, is easier on the throat and is much more pleasurable to smoke.
