It is best to stay safe and not take any risk with poorly controlled experiments. It is scientifically proven that the amount of UV-B rays a plant receives may increase the production of trichomes.
UV-B rays are harmful to other plants (and humans if applied in large quantities), but when cannabis plants receive a large amount of this type of ultraviolet rays, the trichome count can be increased.
We can use this method to greatly increase the amount of trichomes of cannabis plants and thus the amount of cannabinoids.
The lamps we use for the flowering cycle in indoor cultivation called HPS (High Pressure Sodium Vapour) have acceptable levels of UV-B, but are harmful to humans if we are a short distance from the lamp; they are acceptable for cannabis plants . The lamps we normally use for the growth stage of these plants called MH (Metal Halide) lamps emit a much greater amount of UV-B rays than HPS lamps.
This means that if you want to increase the production of trichomes of a plant, just replace HPS lamp by MH during the last two weeks of flowering. This will create increasing levels of UV-B radiation and thus cause the plants to produce good quantity of resin (trichomes).
Some might wonder then why not use Metal Halide lamp all through the flowering cycle. The answer is simple; it is not recommended by the light spectrum. HPS lamps have a much redder spectrum, which is ideal for the development and maturation of buds. On the other hand, MH lamps have a more bluish-white spectrum, which is ideal for the growth stage (development of branches).
By changing the bulb during the last two weeks, you can help the plant create more trichomes and thus be more powerful. There are also specific bulbs emitting UV-B rays, but due to their high price it may not be profitable in cultivation medium.
In outdoor cultivation, things change a lot; we cannot control the temperature and humidity, though we can control the level of nutrients that the plant receives. So, we need to take some extra efforts to add specific fertilizers during different cycles. This will create a more balanced and therefore higher quality plant.
If what you seek is an explosive production of trichomes, you must follow outdoor cultivation on high mountain peaks. At higher elevations, the UV-B radiation from the sun increases and so a plant of the same gene grown outdoors on the top of a mountain to a considerable height will be much the same resinous plant cultivated at sea level for example.
If you opt for this trick to grow on high mountain, then keep in mind that you must measure the room temperature because if it’s frosting then it’s useless even if cultivating at greater height. It is important that the temperature and relative humidity is acceptable.
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