Ultimately, the “magic” that medicinal and recreational tokers seek in their buds is found in the resins produced by cannabis plants. The highest concentration of these resins, naturally, is found in the top buds that typically receiving the strongest light -- especially when growing indoors with artificial light sources.
There are tiny hair like structures found on a wide variety of plants called “trichomes,” cannabis plants that have been selectively bred for higher resin contents tend to have a lot of them.
When you cultivate plants, there are two basic ways to define the characteristics genotype and phenotype. The genotype of the plant is dictated by the genetics inherited through breeding and selection -- this is foundational for growing success, especially indoors. Phenotype refers the physical expression of the gene's the plant has. Basically every chromosome carries a variety of genes that are activated or deactivated, like lights on a switchboard, as triggered by the growing environment.
Traits like resin production are largely genetic. This provides the basic platform of what growers can expect in their yield of buds. However, with modern knowledge of how plants produce resin it is possible to enhance resin qualities using growing style and technology, for example like one grow light over another.
After repeated tests using the same strains and a variety of controlled growing situations it was found that there is cause and effect when it comes to getting better qualities from their chosen medicinal cannabis genetics.
1. Bioactive substances that are naturally occurring can enhance resin content. In simple terms, there are 100 percent natural ingredients in crop nutrient supplements that can stimulate a higher concentration of resins in the buds harvested. This can help to increase dry weights as well as potency characteristics including terpene profiles and production. There is no “silver bullet,” so beware of outrageous claims, but there are ingredients in nature that will increase trichome production and resin secretion in a variety of crops, including cannabis.
2. Lighting Wave Lengths or Grow Light Spectra can be altered, with the most advantage being in late bud or ripening, to create a kind of “light stress” that triggers plants to secrete a more resins; perhaps as a defense mechanism. For example, by incorporating specialized light sources that use far red LEDs to tickle the plants will produce resin levels beyond what plants of the same genetics could do without. Seeing is believing.
3. Environmental factors like carbon dioxide levels and temperature will also effect cannabis crop resin production; particularly during the ripening phase proceeding harvest. Lower CO2 levels will allow the plants to exhibit a higher ethylene level, the plant's self-produced hormone that assists in ripening and maturation, which includes resin glands. In some strains, lower temperatures during the final will create a stress that triggers plants to mature. Most cannabis plants, via genetics, take this as the “last lap” signal and give whatever they have left via their trichomes and resin secretion. It also stimulates the resins the maturation of the resin already produced, including aromatic characteristics.
How you handle the crop at and post harvesting will also effect the quality and characteristics of the resins your crop of medicinal buds produced, so handle with care.