High Stress Training, commonly referred to as HST is a range of training methods, with the goal being to manipulate the cannabis plant in a way that will force it to grow larger, with more branches and more growth sites which results in an increased yield.
High-stress training weed plants causes them to respond by releasing growth repair hormones, which improves overall growth, vigor, and harvest.
You can utilize the flagging material tape. String or wire can wrap the plant, putting it under severe stress. For maximum outcomes, high stress training cannabis plants should be done before the vegetative stage, but definitely before stressing plants during flowering phase. The tape should be left on for up to a week. If the plant “bounces” back after being removed, carefully break up the stem at the curve with a fingernail or knife.
There are a few High-Stress Training techniques that we will cover below, bear in mind that they will all cause a substantial amount of stress and hormonal change to the cannabis plant. If you think that your existing growing setup/method is incompatible with HST, then there is the less intense, Low Stress Training method, which will minimize shock to the cannabis plant and keep the vegetative stage to a minimum. That being said, for those looking to get every ounce of potential from their plants, read on.
When it comes to High-Stress Training weed plants, there is possibly no more effective way than super cropping. This method refers to the act of pinching and bending a branch (a few nodes down) at a 90-degree angle, intentionally crushing the plant’s inner fibers, while leaving the outer structure intact.
While it might seem counterintuitive, this kind of stress actually benefits your plants, encouraging more vigorous vegetative growth and better bud development. In response to predators and other forms of stress, female plants naturally produce cannabinoid and terpene-rich trichomes. Thus, the damage you inflict when super cropping is believed to trigger the plant’s defense mechanisms, causing it to take up more nutrients, and fuelling its growth.
Novices can, and will, accidentally damage the outer structure of the plant while mastering this plant bending technique, but that can be rectified by bandaging the break with plant tape. Due to the ‘damage’ from super cropping a branch, a bulging woody ‘knuckle’ will develop, which actually makes it stronger and able to support heavier loads.
As with any form of High-Stress Training, slightly longer vegetative periods are required so that the plant can recover before going into bud production. If you don’t give it time to recover and grow its woody knuckle, then you run the risk of infection.
It is in no way advisable to supercrop once in flower as all the plant’s energy should be going into bud production, not recovery, plus the hormonal changes from HST in flower can cause hermaphroditism. Bending stems during flowering can lead to stems breaking and losing yield. The best time to supercrop is a week or so before you flip to flower and the plant begins to stretch. Super cropping the main stem during veg is fine to do, so long as it is still supple enough to not snap.
Lastly, one of the other main reasons for super cropping is to bring down the height of any branches that are well above the canopy, this ensures a more even spread with even more growth sites. While you may damage one or two branches learning this technique, it will be worth it in the long run.
Mainlining is, in essence, topping (we’ll cover that below) the plant multiple times, and Low Stress Training the branches down. Using this method, you can achieve 8–16 colas that will be equally sized and of equal height.
Having more colas is great in itself, but by using a step-by-step high-stress training guide to mainlining you will achieve colas of uniform height and size, which keeps the canopy level and optimizes light absorption.
Training cannabis plants in this way turns them from a traditional plant with a main central stem to a Y shape instead, this diverts nutrients and other essential items equally up the two main stems before dispersing (equally again) to the other Y branches.
By bending the branches down horizontally, you ensure each one is an equal distance from the root system, which helps promote consistently sized, dense colas.
Like all forms of HST, there is a recovery period after ‘damaging’ the plant. This high stress is beneficial when executed well, but regardless, there will be time added to the veg period before you can flip her to flower.
The actual Mainlining process is as follows
When your plant has 5–6 nodes, cut it just above the 3rd node (set of leaves) and remove everything below the 3rd node. Tie down the two remaining branches, so they are horizontal.
Once she has recovered and each of the two branches has 4 new sets of leaves, you can top again. Make the cut above the 3rd node on each branch, but this time you only need to remove the 2nd node, leaving the 1st and 3rd nodes intact, then tie down the branches.
Repeat this process one more time to get 8 colas, or twice more to get 16 colas.
Fimming is difficult to get right, but has little downside to getting wrong. With fimmed cannabis, you’re effectively topping two tips at once. Your cuts will go through the primary tip and the nascent tips growing inside it when you cut through the tip. It results in four heads sprouting from the top of the stem instead of simply two. Further down the crop, when you fim cannabis, it encourages broad lateral bushy growth, stimulating lateral branching and side shoots. If it’s an unsuccessful fim, you will likely just get two new heads sprouting, effectively the same as topping.
Fimming is most effective when you are limited in space or amount of plants, a bushier plant with a large amount of heads is appealing in both scenarios. As mentioned before, fimming a plant successfully has great benefits, while an unsuccessful fim still has good benefits.
Whenever you are making cuts to your plant, you should ensure to use clean, sharp equipment to avoid disease and give yourself the best chance of success.
Let’s begin by discussing the difference between lollipopping and regular defoliation. Regular defoliation aims to increase the amount of light and air reaching all plant sections. Defoliation provides equal opportunity to all buds, rather than favoring just those at the very top.
Lollipopping is basically pruning anything that isn’t going to get adequate light towards the end of the grow. The result is a plant that resembles a lollipop, bushy at the top with a bare stem for the lower half. The benefit to this technique is more air flow which reduces chances of rot, but more importantly, the plant’s energy will be focused entirely at the top of the plant where the colas will be forming. With the removal of the lower branches, you eliminate any small fluffy popcorn nugs that are a hassle to trim and contain little value.
Lollipopping any cannabis plant is a good idea, but a lot of autoflower growers find it to be the only method they utilize with a ScrOG system, which relies on a flat canopy with little to no light penetration. The lack of growth under the canopy ensures all the plant’s limited resources go to producing the most fattest flower at the top.
Last, but not least, is the ever-popular method of topping.
Topping is the technique of cutting the top branches of a cannabis plant to limit upward growth and encourage lateral growth in the lower branches. In essence, it turns one stem into two. More lateral development equals more flowering opportunities.
But how many nodes before topping your plant?
Topping shouldn’t be attempted until your plant has at least 4–6 nodes (sets of leaves).
This allows the plant to recover from the shock of topping by having enough stem and root development. Topping should be avoided during the flowering stage, as the added stress while trying to produce buds can send it back to its vegetative stage. Keep in mind the type of cannabis you are growing when topping, sativa will grow quicker than indica, so if growing indica, give it another week of veg to recover.
Before making any cuts to your plant, ensure you are doing it the correct way, any unnecessary stresses to the plant will reduce yield. Topping is one of the most popular weed training techniques out there for a reason, simple yet effective.
At the end of the day, it’s all about quality and yield. These are both vastly improved by employing one or more forms of high stress training. More branches mean more growth sites, more growth sites means more buds. Less plant matter under the canopy means more efficiency where it’s needed at the top. A larger number of colas per plant reduces the quantity of seed per cycle, reducing your overall cost/labor. Training weed plants is the quickest and best way to learn what is possible with cannabis.
The canopy’s height is likewise controlled so that it remains at the same height as when the seedlings were snapped. Using the method of super cropping, producers with restricted head height may control the vertical development of the top canopy.
However, mainlining is a better option than a single super cropping session for people who can only produce a few little plants. During the vegetative period, there is a lot of trimming, and the side branches need to be tied down in a symmetrical pattern.
The disadvantages of some HST methods are mainly limited to autoflower cultivars.
Autoflowers generally don’t have the time to recover from high stress, as they will begin flowering quickly from seed, whether you like it or not. Depending on the amount of stress inflicted on the plant, there will be an according recovery period, which will add to the time spent in veg. Stressing plants during flowering is the last thing you want to do, so it’s best to LST during this stage. There is also the extra time spent training your girls, but this is rewarded in spades. If you make mistakes, there will be extra time added to the growth cycle.
Learn one thing at a time. Stress training weed in any form carries risk, so if you have 4 plants of the same variety, maybe don’t try 4 different HST methods. Rather try two or even just one method on all 4. Consider leaving an untouched control plant to compare against, but be aware this will likely grow in its Christmas tree-like apical way, so it may very well grow taller than the others.
All high-stress training techniques were stumbled upon through trial and error. So, find what tickles your plant’s fancy and become a master of it! By leveraging the cannabis plant’s response to outside stresses, we’ve unlocked their full potential in terms of trichome production and eventual yield.
Remember, different varieties have different preferences. Just because fimming works wonders for one, doesn’t mean it’s the top choice for another. It’s all about knowing your plant and slyly manipulating it. Becoming a master grower takes time, but the possibilities are endless.
Sam N. is a content writer with a passion for everything cannabis. After working multiple seasons on weed farms absorbing the ins and outs of cannabis cultivation and culture, he decided to transition into a role that would allow him to work from anywhere, anytime. Sam now writes for multiple weed publications. He has extensive experience with a wide range of canna-agriculture styles, from smaller artisanal farms to large-scale commercial operations, and is here to share his knowledge to give you all the best chance of cultivation success. About this Author