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What Is THC and How To Increase THC

Created by
JoshuaHolt JoshuaHolt
Added 9 October 2020

How To Increase THC

Any stoner would probably agree that THC is one of the top priorities when it comes to choosing their weed. Whether you are simply looking to get more 'high' or need a stronger medicinal product, boosting THC is a possibility. 

With the huge developments happening in the cannabis breeding sector, we now have plenty of knowledge about different strains and how effectively they can be grown under certain conditions. When cultivated properly, some cannabis genetics naturally produce high amounts of THC. However, there are a few things we can do to maximise potency even before, during or after completing a grow. This article teaches you how you can increase THC production to get even stronger buds.

What is THC?

THC stands for tetrahydrocannabinol. THC is a cannabinoid compound found in the trichomes that cover a cannabis bud during flowering. THC is responsible for the 'high' we experience when we smoke or consume marijuana.

THC is not the only cannabinoid present in cannabis. Although relatively small compared to THC, there are some other compounds that contribute to the effects of consuming weed, such as CBN, CBD, CBV or THCV.

THC (tetrahydrocannabinol) Chemical Structure

How to Increase THC

Increasing THC mainly comes down to optimising your grow conditions and environment. An unhappy cannabis plant cannot function properly so the first thing to do is make sure your cultivating space provides the adequate temperature, humidity, lighting, ventilation and hydration.


Choosing the right strain before you start growing makes a big difference if you are looking for potency. It goes without saying that not all cannabis genetics produce the same amount of THC. Most breeders give you an indication of the percentage of THC a particular strain can produce. 

Some genetics produce low THC of around 14%, whereas there are others on the market that reach up to 27 - 28%. Overall, there isn't one strongest type of weed. Getting the most THC out of your favourite bud requires you to provide and do exactly what is needed for the duration of the grow.

THC Content Can Be Higher In Some Strains


We can increase the production of a cannabis plant by using various training techniques (LST/HST) to manipulate its shape and size. The benefit of applying these methods means cannabis plants make efficient use of their available space and light. Training techniques often result in a flat canopy with evenly sized top buds.

LST and HST Can Help To Increase THC

Training cannabis plants gives them the chance to produce more THC per square metre. Apart from more bud, the manipulation of branches or leaves actually causes stress, meaning the plant has to work harder to stay healthy.

Stressing a cannabis plant has its benefits if it is properly controlled. Depending on the technique, inducing 'stress' can force a plant to strengthen itself for reproduction. This survival mechanism results in more resin, creating a sticky layer as a form of protection and to increase the probability of a male mating with her.

LST performed on Glookies by Coughy from GrowDiaries


Lighting plays an important role in the development of cannabinoids and terpenes. Photosynthesis allows a plant to convert light into useable energy, both for growth and blooming. Without the proper light, a cannabis plant cannot thrive. 

The rule of thumb when it comes to grow room lighting is to give between 30 - 50 watts per square foot. It is much more complicated than this, but if you are trying to increase THC, then make sure you use a light with enough output for the size of your grow space. 

Lights that are not powerful enough for the size of your grow will likely result in decreased THC content as the plant is not able to photosynthesise correctly. The spectrum is important but the intensity is just as, if not more necessary for those looking to boost THC levels.

High Quality LEDs Can Provide The Right Spectrum For Vigorous Growth

LEDs allow us to specify the light spectrum received by plants. That means we can give a cannabis plant exactly the kind of light it needs, when it needs it. Blue and red light have proven to be essential for proper growth, however other colours are worth investigating too. There are theories about how ultraviolet light affects THC levels but this needs to be studied in more depth.

Growers have experimented with different spectrums to find out how lighting can improve plant health, yield and potency. Cannabis plants benefit from plenty of red light during flowering. Red light mimics the end of the summer season when higher concentrations of red light penetrate the atmosphere. It is essential for the healthy development of trichomes and cannabinoids.

Tip: If your plants are looking burnt, you may need to position your lights further from the canopy. Lights that are too intense can scorch plants which may slow them down.


A Healthy Cannabis Plant Will Provide Maximum Yields

Some cannabis plants can handle heavier feeding schedules, which can improve THC content. Too much fertilizer may also be problematic for nutrient absorption so the right balance needs to be met. Either way, providing your cannabis plants with the correct levels of nutrients gives them the ability to produce most effectively.

Deficiencies can lead to small harvests of buds that did not reach their full potential. It is possible for a cannabis plant to survive on just water, but yields will be low and THC content will likely be below what it could be.

Knowing your strains well can help you understand what they can and can't take when it comes to feeding. This is why it's advised to stick with the same strain for multiple grows, so you can learn the comforts and limits of your ladies.

Harvest Time

Picking the perfect time to harvest can determine the strength of your buds. Every cannabis plant will have a point of peak THC during the harvesting window. Harvest too late, and potency will begin to drop.

After flowers fully ripen they begin to degrade as the plant cannot produce any more. Organic matter starts to break down, including the precious cannabinoids we want to preserve.

To achieve the highest THC level possible we need to take a closer look at the trichomes developing on the top buds. Trichomes are the resinous 'hairs' which give cannabis that frosty, sparkly, or snowy appearance. You will know more or less when harvest day will be based on your strain's flowering time.

The pistils can also be checked for maturity but bear in mind the colour change will depend on the strain, so make sure you check the trichomes as well. When they are ready for harvest, most strains' pistils will turn amber/brown, whereas as others may stay white. You can use this data sheet as a guide, but we recommend learning your favourite strains well so you know when is the best time to harvest for peak THC.

Amber Pistils




Too early

Low potency


Beginning of harvest period

Mellow high


Reaching optimum level

Slightly Psychoactive


Peaking THC content

Potent/Psychoactive high


Peak THC content

Potent high


THC starts to break down

Stoned/Sedative effect

Towards the end of the flowering period, check the trichomes daily with a magnifier or mini microscope. Trichomes that are cloudy or milky signal that a plant could be ready for harvest. If there are still a lot of clear, glassy looking trichomes, you may need to wait a day or two more.


Curing Cannabis Can Help To Increase Potency

Curing is a key stage in the cannabis cultivation process. After harvesting, a cannabis plant will continue to try and metabolise cannabinoids. Increased THC content occurs from the metabolic change in certain compounds present in the bud.

Properly drying and curing your buds can help with the slower chemical breakdown of these cannabinoid compounds, resulting in a much tastier, potent product. Curing can continue for up to 6 months after placing buds into mason jars. After that there is not much point, as the THC begins to degrade, which reduces potency.


Maintaining standards in your grow room is the best way to ensure THC content is at its fullest by harvest day. Preparing your space correctly sets you up for producing lots of sticky buds, but fine tuning your practice can mean the difference between an average harvest or one that completely knocks you back into your chair. 

Connecting with growers can help you take it that step further, so why not consider engaging with the community in the comments section below. 

External References

Molecular Pharmacology of Cannabinoids: Beyond THC. - Sachdev, Shivani. (2020)

Cannabis sativa: Much more beyond Δ9-tetrahydrocannabinol. Pharmacological Research. - Alves, Patrícia & Amaral, Cristina & Teixeira, Natércia & Correia-da-Silva, Georgina. (2020).

This article was updated September 2020.



Very Very Good Article ! Read every word. Great work guys :pray:


Also more uv b lighting and days of darkness before harvest, and cold temps in last weeks of flower and low humidity during flower especially last weeks


@Slurpy_Terpy, We are currently writing an article on increasing trichome production, which will include some of the topics you mentioned :grinning: Thank you for your comment! :+1:


Nice reading, thanks! @JoshuaHolt, is it not rule of thumb 30-50W per square foot?

2.c. Lighting
...The rule of thumb when it comes to grow room lighting is to give between 30 - 50 watts per square metre...


@M420_GROWS, Thank you for pointing that out! :+1:


Nice article, covers most stuff in a very full picture mode, not very specific, but in a very good way!