10 top tips to increase the production of trichomes in the last weeks of flowering

If you grow cannabis, your goal is probably to make it as tasty and potent as possible. To achieve this, you’ll need to maximise the production of trichomes. The final flowering phase is a crucial time for this, especially during the last few weeks, when the plant focuses its efforts on resin production. Here we’ll explore various techniques and top tips to maximise terpene production and increase THC levels to obtain a more potent and aromatic end product.

In the world of cannabis cultivation, attention is often focused on trichomes, those small crystalline bulb-like structures whose function is to protect the plant from predators, stressful environmental factors, and ultraviolet radiation. Trichomes can also help regulate temperature and prevent excessive evaporation, allowing the plant to thrive in various climates.

But trichomes are also the warehouses of the plant’s active compounds, which include cannabinoids, flavonoids, and terpenes. The more trichomes a bud has, the greater its medicinal and psychoactive power, and the more intense and complex its aroma and flavour. Therefore, knowing how to increase the production of trichomes can be a huge benefit for any grower. Here are some tips to help you achieve this!

1. Choosing the right strain

In terms of trichome production, genetics plays a crucial role. Different cannabis varieties have different trichome densities and resin production capacities. If your strain doesn’t have the genetics to produce lots of trichomes, there’s not much you can do to change it. Therefore, choosing the right cannabis strain is the first step you should take.

Top tip: Look for varieties that have won awards for their potency or are known for their high resin count. Indica-dominant strains like RS-11 or Purple Kush are usually the favourites of growers looking for abundant trichomes. But you can also go for sativas like Cookies Haze or Amnesi K-Lemon, which not only stand out for their high THC content but also for their ability to produce a very generous amount of resin.

2. Understanding the flowering cycle and the maturation of trichomes

Checking the appearance of trichomes is one of the best ways to know when it’s time to harvest. Their appearance determines the potency of the cannabinoids accumulated inside. During the last weeks of flowering, trichomes change colour (from milky white to a darker amber), which is a key indicator that they’re at their finest.

Top tip: You can use a magnifying glass or a microscope to look at the trichomes closely. Most growers harvest when 85% of the trichomes look milky and 15% are amber – this will promote a stimulating effect. A 70/30 ratio is ideal for relieving pain and promoting sleep. It goes without saying that your specific strain will influence the outcome – these are just general rules.

3. Lighting settings: The role of UV-B light

Lighting is a determining factor in the production of cannabinoids and terpenes. Research suggests that exposure to UV-B light in the last weeks of flowering can significantly increase resin and THC production. When plants are exposed to ultraviolet light, they create natural sun-screening compounds, just as humans produce melanin and tan when exposed to sunlight. This reaction to exposure to specific light wavelengths is called photomorphogenesis, and it increases the activity of the secondary metabolites of cannabis (i.e., cannabinoids like THC and CBD) as an evolutionary safeguard response.

Top tip: You can use UV-B lamps during the last 2 – 3 weeks of flowering, always keeping them on for short periods (ranging from 15 minutes to 2 hours per day). And always taking care not to burn the plants.

4. Temperature and humidity control: Controlled stress stimulation

During the last weeks of flowering, the goal is to replicate an environment that encourages the plant to produce more resin to protect itself. And lower temperatures can have a noticeable effect on the quality and quantity of trichomes, helping to preserve terpenes (which are responsible for the aroma and taste of cannabis). Lower humidity levels can also alert the plants to protect themselves from dehydration and produce more trichomes.

Top tip: Keep the temperature between 18 and 24°C during the day, and drop it to 15 – 20°C at night. Reduce humidity to 30 – 40% in the last few weeks to prevent the appearance of mould; and use fans and extractors to keep a constant air flow.

5. Irrigation and nutrition techniques: Less is more in the last few weeks

Water stress is another advanced technique used by some growers to increase resin production. By limiting the watering in the late stages of flowering, the plant can produce more trichomes in response to stress. Having said that, this method should be applied with caution to avoid damaging the plant.

To maximise resin production and improve the quality of cannabis, many growers also opt for “root-flushing” techniques. This practice involves watering the plants only with water to remove the nutrients accumulated in the substrate and therefore improve the user experience.

Top tip: Start to reduce the amount of water you give your plants during the last two weeks of flowering. Don’t let the plants dry out completely, but instead allow the top layer of the substrate to be drier than usual before watering again. For the root flushing to be as effective as possible, use pH-adjusted water: 6.0 – 6.5 for plants in soil, and 5.5 – 6.0 for hydroponic setups.

6. Advanced techniques: Controlled stress by applying Supercropping and defoliation

Some growers believe that subjecting the plants to mild stress can increase trichome production, on the basis that these techniques can redirect their energy towards trichome production as a defence mechanism. However, it’s important to note that they should be carried out with caution and only by experienced growers.

Top tip: You can use techniques like “Supercropping”, which involves carefully bending the branches without breaking them. Or you can perform a selective defoliation, removing the large leaves that prevent the light from reaching the lower buds, thereby increasing exposure and improving air circulation.

7. Photoperiod manipulation: Reducing the hours of light

Simulating an end-of-season environment, where the days are shorter, makes the plant increase its resin production. By reducing the hours of light, the plant perceives that it is approaching the end of its life cycle, which encourages it to go into “survival mode”. This state of moderate stress causes it to concentrate its energy on protecting its flowers (which are its means of reproduction) by producing more resin. This trichome-rich resin not only protects the flowers from pests and UV rays, but also enhances their reproductive potential by attracting pollinators.

Top tip: During the last two weeks, reduce the photoperiod to 10 – 11 hours of light per day to mimic the shorter days of autumn. This adjustment should be done slowly and in a controlled manner to prevent the plants from experiencing severe shock, which could cause excessive stress or even hermaphroditism (the appearance of male flowers on female plants).

8. Darkness before harvest: A technique with as many followers as detractors

As with root flushing, giving cannabis plants a period of darkness before harvest time is also a highly debated method. This theory suggests that this period indicates the end of the season, once again causing the cannabis plant to make a last attempt at survival, with increased trichome production being an important part of it.

Top tip: Some growers use a 0/24 photoperiod for the last two days instead of 8/16. This means zero light exposure for 48 hours. Many growers are against this practice and claim that it provides no benefits whatsoever. Others defend it and keep all their grows in the dark before harvest time. This isn’t harmful to the plant (as long as the growing medium is sufficiently hydrated), so feel free to experiment however you like.

9. Adding carbohydrate supplements and resin enhancers

Products containing complex carbohydrates, amino acids, and resin enhancers can provide an extra boost. For instance, plants use sugar as a source of energy (just like humans) to produce flowers. A little extra sugar can make the buds bigger and stickier.

Top tip: Add supplements such as molasses, which provides essential carbohydrates and micronutrients. You can add it to the irrigation water during the last weeks of flowering. You can also use resin enhancers specifically formulated for the final stage of ripening (but make sure you always follow the manufacturer’s instructions).

10. The importance of proper drying and curing

The maximisation of cannabinoids and terpenes does not end with harvest. Proper drying and curing are essential to preserve THC levels and improve the organoleptic profile of the cannabis obtained. The curing process allows compounds to develop and stabilise, improving the taste and potency of the final product.

Top tip: Dry the flowers in a dark environment with a temperature between 18 and 22°C, and a relative humidity of 45 – 55%. Cure the buds in airtight jars, burping them daily for the first two weeks to facilitate moisture release and prevent mould build-up.

And a final piece of advice that’s as important as all the rest

Maximising cannabinoid and terpene production during the last few weeks of flowering requires a combination of advanced techniques and careful monitoring of the environment. Adjustments in the lighting, temperature and humidity, irrigation techniques, and the application of controlled stress methods can all make a difference between a standard and a top-notch grow.

We recommend that you get comfortable with your way of growing before moving on to the techniques described above. Achieving the perfect conditions requires a lot of learning and experience. Once you’re satisfied with the cannabis plants you’re growing or have enough plants to experiment with, why not try giving them that last extra boost?