How to Increase THC When Growing Weed
Table of Contents
Increasing Cannabis Potency During the Growing Process
When it comes to growing cannabis, there are lots of different goals by different growers. Many growers are growing medical marijuana for medical-related purposes. Others are growing for their personal adult use. For many growers, including both medical marijuana and recreational cannabis growers, a common goal is to maximize the amount of THC and other cannabinoids produced when growing cannabis (ie increase the “potency” of your buds).
This cannabis bud was grown to produce the highest levels of THC possible – as a side effect it is dense, sticky and looks great.
Why Increase Maximum THC Levels?
- Greater mental and psychoactive effects from the same amount of bud (your harvest will go further!)
- Many medical marijuana growers desire high THC levels for the relief of nausea, certain types of pain, spasticity, certain symptoms of multiple sclerosis, etc.
- Many of the things you do to increase THC levels will also increase your overall cannabis yields.
However, not every grower wants the highest levels of THC in their bud, and may actually be seeking other cannabinoids found in certain strains. For example, there are many medical marijuana growers who prefer low-THC, high-CBD cannabis, which is non-psychoactive and may be of interest to those looking for possible relief from anxiety or seizures. Learn more about the difference between CBD and other cannabinoids like THC (unfortunately you can’t use grow methods to increase CBD levels, you need to start with a low-THC, high-CBD strain).
Much of the THC and “potency” in your buds is contained in the sparkly trichomes
What increases THC levels and overall potency?
These are the most important factors that will affect your THC levels and overall marijuana potency:
Strain & Individual Plant Genetics
Your plant’s genes are hands-down the most important aspect of cannabis potency when it comes to growing!
Your plant genetics set the “upper limit” of how much THC and other cannabinoids your plant will ever be able to produce. Although you can use grow methods to maximize the THC within that limit, you will never be able to overcome the limits set by your strain and plant genetics.
So as a really rough example, let’s say your strain/plant genetics can only produce 15% THC at most. That means you may get less than 15% THC in your buds if you don’t grow the plant right, but no matter what you do you’ll never be able to increase it above 15%.
In order to get really high levels of potency and THC, it’s essential to start with high-potency, high-THC genes from a respectable breeder. Learn how to research strains so you get the most potent cannabis plant to fulfill your needs. If you’ve never ordered cannabis seeds before, learn how to get seeds delivered to the US and worldwide.
Some strains just don’t have the genetics to make cannabis buds as potent and trichome-covered as the one pictured here! Unfortunately, there’s nothing you can do to beat genetics so start with good genes!
Many cannabis growers don’t realizing they are actually harvesting their buds too early, dramatically reducing yields and potency!
There is a 2-3 week period during the flowering stage when plants are “mature” and buds are at the highest levels of THC. At this point, the tiny resin glands (trichomes) on the buds have turned milky white, and most of the white hairs (pistils) on the buds have darkened and curled in.
Highest Level of THC When…
Most white pistils have darkened and curled in (bud looks more “solid”)
Most clear trichomes (looks like glass) have turned white (looks like white plastic)
If the plant is allowed to keep maturing, the cannabinoid profile continues to change. Buds harvested on the later side tend to produce more of a relaxed “body” effect, though the psychoactive effects of THC may be somewhat reduced.
If you harvest earlier than this, the plant hasn’t reached its full potential. Sometimes early-harvested buds can produce a “speedy” effects, or give some people headaches (curing will help with this) so avoid harvesting early if you can!
Learn more about when to harvest cannabis (with lots more pics!)
Get the effects you’re looking for!
This cola has several weeks to go before it reaches its highest THC levels – harvesting now will reduce both your yields and your potency!
Plant Health & Care
In order to get your cannabis to produce the most potent buds possible, you need a robust, healthy cannabis plant with lots of bud sites getting direct light during the flowering stage. This means it’s important to avoid common plant health mistakes like overwatering, underwatering, heat stress, root problems, irregular light cycles, and nutrient problems. Check out our 7-step remedy to fix most cannabis plant growing problems. Try to maintain balance and avoid environmental extremes. Basically, treat your cannabis plant like it’s a celebrity – it gets everything it wants!
Although cannabis can grow in relatively low light conditions (it grows like a weed!), it will not produce significant amounts of bud without very bright light in the flowering stage. Cannabis uses light to power the growth of buds, along with the THC and cannabinoids contained inside. Outdoors your plant needs direct sunlight 8+ hours a day to produce to its fullest, and indoors you need strong, bright grow lights (like LEDs or MH/HPS grow lights) to produce the highest levels of THC.
Although there is no evidence that the curing process (jarring up buds after they’ve dried) increases THC levels directly, there is a lot of evidence that it increases the perceived potency of buds.
Though not well understood, this may be because there are chemical changes that happen during the curing phase that “intensify” the effects of THC and other cannabinoids.
The curing process also has other benefits for marijuana growers. For example, newly dried cannabis buds often smell like cut grass or hay, even if they smelled great in the flowering stage. The curing process helps get rid of the unpleasant grassy taste/smell and brings back the natural taste and smell of the cannabis plant.
Lastly, uncured and early-harvested buds can cause “speedy” thoughts or headaches for some people, and curing often reduces these negative effects.
Common Myth: Using CO2 increases THC levels
Although it’s true that using CO2 can increase your overall cannabis yields, there isn’t any evidence that it actually increases the potency of your bud. Learn about other ways to increase yields.
Unknowns: These Growing Methods May Increase THC But Aren’t Well-Tested
These are some of the common ways growers try to increase the THC levels of their cannabis. These techniques and methods are considered “unknowns” because there hasn’t been a whole lot of scientific testing to see what works and what doesn’t work as far as increasing THC.
Supplements to Increase THC and Overall Potency
There are many supplements for growing cannabis, and each one has a different purpose. Some supplements are great, while others are just snake oil.
When it comes to supplements for bud quality, most claim to increase yields or flavor as opposed to potency. However, there are some supplements that either claim or insinuate that they will increase the potency and/or THC levels in your cannabis.
Unfortunately, at this time there aren’t any supplement companies which have conducted systematic tests showing that their supplements will actually increase THC. Because of this, although it seems possible that some of these do work as stated, I can’t recommend any ones in particular.
If you know of any supplement manufacturers who have actually tested their products on real cannabis plants and can demonstrate that their supplements actually increase THC, we’d love to hear from you!
Allow Plant to Remain in Vegetative Stage For 8+ Weeks
I’ve heard this one from different growers over the years, but for now, the jury is still out. The idea is that a cannabis plant needs to remain in the vegetative stage for at least 8 weeks before being switched to the flowering stage in order to reach its maximum THC levels when it starts budding.
Cannabis plants which have been allowed to grow for at least 8 weeks in the vegetative stage tend to be much bigger and more robust than plants switched earlier, and they produce far greater yields. But does that mean that they produce higher levels of THC? It seems like it could be possible, but it might also be related to other factors. For example, big plants are usually grown under powerful grow lights, which affects potency, and are also often grown by more experienced growers. More testing is needed!
My idea for a test (hopefully someday I’ll get to do this when I get more room to grow!)
- Sprout several seeds from a very stable cannabis strain like Northern Light to reduce genetic variation between the plants
- Allow each seedling to grow out to 8 weeks in the vegetative stage, then take a clone off each plant. Although clones are the size of seedlings, they are the same internal “age” as their mother so in a way, these clones would already be 8 weeks old
- Sprout more seeds of the same stable strain and grow them until they’re about 3 weeks old so they’re the same size as the clones. You want to time this so that the seedlings are about 3 weeks old just as the clones are the same size and taking root. Seedlings can’t start flowering before 3-4 weeks old and we’re trying to create as close to the same conditions as we can between the two plants to reduce as many variables as possible.
- Now that you’ve got your 3-week seedlings and your “8-week” clones that are the same size, flower them together in the same conditions.
- After harvest, test the THC levels! If the buds from the clones are more potent than the ones from the seedlings I’d say it’s pretty good evidence that increased age increases potency. If not, well, back to the drawing board to try another test!
Letting plants get older before the switch to the flowering stage definitely results in bigger plants and higher yields, but we don’t know if it increases cannabis potency!
Lack of Pollination (Producing “Sinsemilla”)
Just a few decades ago pretty much all cannabis bud you could find was full of seeds. This is because at the time many growers didn’t realize that male and female cannabis plants need to be separated in the flowering stage to prevent the female plants from getting pollinated and making seeds.
However, once cannabis growers became more aware of growing techniques including how to prevent pollination, there was a rise in “sinsemilla” weed, a word which combines the Spanish word “sin” (without) and “semilla” (seed) to mean cannabis “without seeds.”
Seeds belong in your garden, not in your buds!
The sinsemilla bud that started flooding the market was much higher potency than the seedy, low-quality bud that had been available before. This led to the term sinsemilla being used to describe very high quality and potent cannabis. There’s no doubt that most growers prefer buds without seeds, but the term sinsemilla has led to the idea that cannabis buds without seeds were inherently more potent than seedy bud.
While this may very well be true, there isn’t much evidence that it’s actually the lack of pollination which caused the dramatic increase of potency experienced by cannabis enthusiasts at the time. Right around the time growers started producing non-seedy buds, the cannabis breeding scene was also starting to get established. Publications to assist cannabis growers like the High Times magazine appeared on the scene to help growers learn better growing techniques, and cannabis breeders like Nirvana started shipping cannabis seeds of famous strains to growers all around the world by mail order.
High Times Top Strains of 1977
Growing and breeding techniques were improving simultaneously. It’s possible that the increase in potency experienced by people who switched to seedless buds was actually the result of better genetics/breeding. These days, most people only get sinsemilla and no one really wants to do direct comparisons.
However, keeping buds from producing seeds will dramatically increase the perceived quality of your buds, as well as your yields, so regardless of whether it increases bud potency or not, it’s something every grower wants to do! Don’t let your female plants get pollinated – remove all male plants from your grow room immediately (or start with feminized seeds, which don’t produce any male plants)!
Type of Grow Light & Spectrum – HPS, LED & LEC Grow Lights
Different types of grow light produce different spectrums (colors) of light. There are some growers that believe that growing cannabis under the unique light spectrums of LED grow lights or LEC grow lights may increase resin production and THC levels. Other growers swear that you need powerful HPS grow lights to produce the highest levels of THC.
Special Ways of Flushing
During the flushing process of growing cannabis, a grower generally gives their plants just plain water for the last few weeks before harvest. This is done to encourage the cannabis to “cannibalize” itself and use up all remaining nutrients in the plant.
The idea is to get the plant to use up any nutrients that may have built up in the buds which could possibly affect that taste/smell after harvest
However, there are several additional types of flushes that many growers believe will increase THC levels. Most of these are done in addition to regular flushing, just before harvest. Unfortunately, there aren’t many (if any) tests determining which one of these work, but there are many experienced growers who swear by these methods!
Unfortunately, they don’t all match (for example some growers say to harvest in the morning, while others believe you get more THC if you harvest during the plant’s dark period), but these are the most common flushing techniques that I’ve heard to increase THC levels right before harvest.
These “flushing” methods may (or may not) increase THC:
- keep plant in the dark for 2-3 days before harvest
- harvest cannabis in the morning
- harvest cannabis during the plant’s dark period
- water plants with ice water before harvest
- chop down and hang entire plant upside down for a few days before trimming and drying buds
Air Temperature, Humidity and Overwatering
I wrote this section after reading the results of a 6-year study about industrial hemp. Although hemp is closely related to the cannabis, they’re not the same thing so these finding should definitely be taken with a grain of salt. In the study the researchers found the following environmental factors were associated with higher levels of THC:
- High humidity
- Warm air temperature
- Lower levels of precipitation (rain)
Since the study is based on hemp grown outdoors, it’s hard to know if these factors will influence the THC content of cannabis plants grown indoors, but I do think it’s a good idea to keep things warm (at least above 70°F/20°C which is the minimum recommended temperature for optimum growth) and avoid overwatering!
Common grower knowledge says that lower humidity towards the end of the flowering stage will raise THC levels, but this study makes me want to look into that further since the hemp in the study actually produced higher levels of THC at higher humidities!
Conclusion: Time to Grow More Potent Cannabis!
There are certain techniques that will definitely maximize the THC produced by your cannabis, and there are other methods which may increase potency but their effects are less certain.
If you are serious about increasing the THC levels in your cannabis, make sure to follow the top steps which are known to increase potency! Skipping any of those steps will reduce your potency for certain! Choosing the right strain, giving plenty of bright light, taking great care of your plants while they’re alive, and harvesting/drying/curing properly are the most important steps you can take to increase the THC levels of your buds!
But luckily for cannabis growers, most of the “unknowns” can’t hurt your plants, so there’s no harm in trying them out, too!
There are a few growing techniques known to increase the THC of buds, as well as several "unknowns" which may also have a big effect on potency. Learn what you need to do to get the results you want!
How to Increase THC in your Cannabis Plants?
One of the main reasons you smoke cannabis is just so you get knocked out. Sure, there are medicinal cannabis users that prefer CBD, but for recreational users THC is king. There’s nothing more satisfying than smoking or ingesting cannabis that blows your mind. But, the caveat is that not all strains make you high.
Cannabis users love that elusive THC that sends their creative minds thinking. And, cannabis growers are always looking for ways to increase THC. It’s not child’s play, but it can be done. So, today, we’ll teach you exactly how to increase THC in your cannabis plants.
Why increase THC?
You’ll rarely find someone that doesn’t love some dank potent cannabis. Almost every recreational smoker loves THC – Tetrahydrocannabinol. The higher, the better. Whether you’re growing for personal or commercial purposes, everybody appreciates some hard-hitting cannabis. As long as you don’t overdo it, THC can actually work wonders. Like CBD, THC also contains medicinal properties, but that’s a topic for another post.
How to increase THC
There are several ways to increase THC in the plants you grow at home. And, they include:
Do your homework before you purchase seeds. For instance, Gorilla Glue is pretty famous to knock you down. Some tests reveal that it comes with a whopping 24% THC with low levels of CBD. That’s the kind of strain you should be looking for. Another strain that packs a punch is Girl Scout Cookies. No matter what you choose, make sure you educate yourself about THC levels of the strains.
As you can surmise, your quest to increase THC begins before you even purchase seeds. If you buy seeds that’s guaranteed to produce high amounts of THC, half of your work is done already. Keep in mind that the way you grow plants also determines the levels of THC. Beginners usually don’t get yields with high THC because you need experience, but if you continue without getting disappointed, you will be able to grow buds that are nothing but THC machines!
Okay, now that you’ve bought some high-THC strains, what next? Well, the next thing is to pay attention to the health of the plant. It’s no secret that happy and healthy plants with amazing genetics produce high levels of THC. And, that’s what you should be focusing on.
But, how do you make sure that the plant is healthy? Firstly, you need to take care of the roots. Start by choosing good containers that help the roots breathe and branch out. Smart pots and airpots are perfect for this because they are designed to aerate the roots.
Next, do not over-water. It’s okay if you don’t water too much, but cannabis plants with their feet wet constantly will either wilt and die or produce small yields with little to no THC.
Cannabis plants love loads of light. They just can’t do without it. Autoflowers, for instance, grow with even 12 hours of light but you will notice a huge difference if you provide 18 hours of light and 6 hours of darkness. Some growers go by the 24/0 light cycle but that’s not necessary. Like humans, plants need some rest and a lot of light will deter their progress!
There are so many varieties and types of lights available in the market today that you’ll be spoiled for choices. Read the manufacturer’s instructions and pay attention to the wattage of the light. Obviously, the more the wattage the stronger the light, but you should also purchase lights depending on the space you have.
Generally, the plants will be happy with about 40 to 50W of light per square feet. Keep this in mind before purchasing lights. If you have a small place, set up a lighting system accordingly. Additionally, make sure you set up lights that have UV light in them. Many LEDs have this option along with Infrared. Basically, cannabis plants produce high amounts of THC when they get ample light.
4. Use training techniques
The point of using training techniques is to stress the plant. But why would you stress the plant? Well, cannabis plants produce more THC when stressed. Generally, plants work harder when they get stressed. You can also reduce watering to stress the plant more. This way, it will produce a lot more trichomes.
So, what are the best training techniques that stress the plant? You can start with topping. FIMming will also work. When combined with LST, the plants will more produce so much resin that the leaves look like crystals studded with sugar (now you know why they are called sugar leaves).
While topping is a process where you cut off the top of the plant after it produces 2-3 sets of true leaves, FIMming also produces similar results. Not only will you help increase the number of colas, but the resin production will also increase.
When LST or Low Stress Training is used along with topping, the results can be dramatic. LST, as the name suggests, is a training technique to stress the plant, but it doesn’t overdo it. It also ensures that all the parts of the plant get more light. By bending the tops of the plant towards the sides of the container, even popcorn buds at the bottom of the plant get more light.
One of the main reasons you smoke cannabis is just so you get knocked out. Sure, there are medicinal cannabis users that prefer CBD, but for recreational users