Managing Nutrients in Commercial Cannabis Cultivation
Nutrient usage and application can be done in dozens of ways, depending on the medium used for the marijuana plants, the watering system, and the philosophy of the cultivators and business owners. The trend for high-end cannabis flowers is towards organic cultivation methods, which includes insoluble substances, usually added as soil amendments, that require microbial activity to become available to plants.
On the opposite end of the spectrum is hydroponic water culture gardeners who use mineral-based synthetic nutrients, which are immediately available to marijuana plants, but can be less forgiving when protocols are not well balanced and followed to the tee.
Either organics or synthetics are best handled in conjunction with lab testing of the input water and runoff, as well as periodic testing of the soil elements in cases where soil and soil-like mixes are used. This creates a real-time picture of what the plants are using and in what proportion, such that the regimen can be continuously dialed in to match the exact strain being grown.
Most frequently growers use too much phosphorus in the flowering phase of growing, causing flower burn and lockout of other nutrients. Further, phosphates are toxic to groundwater and some regulators are becoming conscious of this and beginning to insist upon runoff management in order to minimize environmental damage.
With lab testing and some good handheld meters, custom nutrient regimens can be created to maintain marijuana plants in an optimal state of health by continuously balancing the ratio of the 13 macro- and micronutrients such that very little leaching is necessary throughout the growth process, and the highest possible yields can be obtained. Even when a non-custom name brand set of nutrients is being used, the chances of the marijuana plants uptaking elements in the exact ratio in which they are supplied is near zero. I recommend twice monthly lab testing of the leaf tissue, and for the results to be compared to the input nutrient mix and the runoff. There's no substitute for good data.
A hybrid regimen of synthetic and organic nutrients can be used for a balanced treatment of cannabis plants, which often yields the best possible results between growth rate and flavor. Compost teas can improve the uptake of mineral nutrients as long as the total salt volume of the medium does not exceed the level that can sustain supportive microbial life.