High Stress Training - Complete HST Guide

High stress training your plants sounds counterintuitive - why would you purposely induce harm to your garden?

However, this plant training technique has garnered more and more interest over the years, as it becomes a more mainstream gardening tactic.

Those who HST their plants can manipulate the way their grow room looks, getting the most out of their space and pushing as much yield as possible.

Some growers also claim they increase potency and overall quality (terpenes, flavonoids, bag appeal, etc.) with this method.

There are a few different ways you can induce high levels of stress in your plant to achieve these benefits, each of which will be covered in depth throughout this complete guide.

Before we get into the how, though, we want to cover what exactly these techniques entail - and exactly why you need to give it a try!

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High Stress Training - Complete HST Guide


High stress training your plants sounds counterintuitive - why would you purposely induce harm to your garden?

However, this plant training technique has garnered more and more interest over the years, as it becomes a more mainstream gardening tactic.

Those who HST their plants can manipulate the way their grow room looks, getting the most out of their space and pushing as much yield as possible.

Some growers also claim they increase potency and overall quality (terpenes, flavonoids, bag appeal, etc.) with this method.

There are a few different ways you can induce high levels of stress in your plant to achieve these benefits, each of which will be covered in depth throughout this complete guide.

Before we get into the how, though, we want to cover what exactly these techniques entail - and exactly why you need to give it a try!

What Is High Stress Training?

Referred to as HST for short, this is a form of plant training which tends to induce higher levels of stress. This means your plant will take longer to rebound from these methods.

However, that isn’t necessarily a bad thing. You may see some slow, stunted growth immediately following a training session, but this will be followed by explosive growth, terpene and flavonoid development, and more.

We’ll compare HST vs LST in a bit, but for now, just understand that the former involves physically damaging or removing parts of the plant. There isn’t just one strategy, either.

What Are The Different Forms Of HST?

What Are The Different Forms Of HST?

HST involves damaging or removing parts of the plant - and there are some specific techniques that we want to teach you that all fall under this umbrella of “high stress training”:

  • Topping
  • Defoliating
  • FIMing
  • Manifolding
  • Super Cropping

These all take into account the same principles, but the way in which you’ll damage or remove parts of your plants differs among them.

Some are far easier than others - such as topping or defoliating. Others are a much more complicated process that will require great care and maintenance.

No matter which you opt for, you can rest assured you’ll enjoy heavier yields and higher quality harvests than if you were to simply let your plants grow as intended.

Why Should You Try High Stress Training Plants?

We have already hyped up the “why” behind HST quite a bit. Heavier yield, higher quality, and manipulating the way in which your plants grow.

The latter benefit is one we really want to focus on, particular for our indoor growers. Because you have limited space, you cannot just let your plants grow on their own accordance.

If you do, they’ll grow tall and lanky, with apical dominance taking hold. This is where one or two main colas dominate all the light, nutrients, and plant energy, resulting in smaller yields.

By manipulating your plant’s shape, you can grow it wider and shorter and pack in your plants with plenty of dense flowers.

HST vs LST - Which Is Better For Your Grow?

Now, there are all kinds of different training techniques out there for you to choose from. But at their essence, they can more or less be categorized as either LST or HST.

So which of two categories is right for you? This depends on your goals as a grower. You should try both over the course of your growing career, and see which one yields better results for you.

Can I LST AND HST My Plants?

Some growers combine the two techniques, which can yield some really impressive results when done properly.

You can rely on LST to create an even, level canopy to keep your plants short and bushy. Then, help your plant produce even more budding sites and increase growth rate/quality through HST techniques like topping, supercropping, etc.

Experimenting with different techniques and trying new things is what separates a novice grower from a seasoned green thumb. At the end, we'll share a sample training regimen you can follow that incorporates both LST and HST.

We also have a complete guide on low stress training if you’re interested in learning more about this lower maintenance approach to manipulating growth.

For now, though, we’re going to move onto the different ways you can actually HST your crop!

Different Techniques For High Stress Training Plants

Now, we are going to teach you how to HST your plants. And the first step in this process is learning when to start high stress training!

After we cover the timeline, we’ll share guides on topping, FIMing, manifolding, and supercropping. These are the four main HST techniques that growers implement indoors and outdoors.

When Should You Start High Stress Training?

Most plant training in general should occur during the vegetative phase. And ideally, as early as possible. This gives your plant plenty of time to recover from the stress, and grow in the way you are hoping it will.

But you don’t want to start the minute your seedling emerges from the soil. You need to ensure it is hardened off enough to manage this stress.

Other factors affect when you should start HST too, like whether or not you are trying to combine it with LST. If you are, then LST will come first.

And for the most part, the specific technique you are planning on implementing will dictate exactly when to begin.

For example, you can begin topping once there are 4-5 pairs of true leaves. For supercropping on the other hand, you’ll want to wait until there are a few different branches of growth rather than just leaves.

With all forms of HST, you want to do them while the growth you are looking to manipulate is still young and malleable. This will prevent irreversible damage to the plant, such as snapping a branch off. Fresh, green growth is what you should be looking for.

Can I HST My Plants During Flower?

Some growers try and HST their plants starting in flower. This is a bad idea, because you won't reap the main benefit - creating a flat canopy.

If you haven't done any sort of training to this point, you're too late. And stress you induce now will likely just be detrimental to your yield.

There are ways you can stress your plant out during flower to push out even more bud development, such as temperature and lighting manipulation, flushing, etc. High-stress training is not an option during these final weeks!

Topping - The Easiest High Stress Training Technique

Topping is perhaps the easiest form of plant training in general - let alone HST. All you need are a clean pair of scissors.

This is the HST technique we recommend to beginners, because it’s incredibly straightforward, and results in increased colas while preventing apical dominance.

With topping, all you do is snip the dominant shoot of growth back. In turn, the two next nodes below where you top will take off, receiving all the energy from that main shoot you topped.

As time goes on, you can then top those two shoots. The result is four total shoots of growth - four main colas that will turn into dense, potent flowers when you flip to 12/12.

How Often To Top

You can top as much or as little as you like, but beware - topping every branch in sight in an effort to produce as many colas as possible will eventually have diminishing returns, as your plant will have to spread budding energy across so many different colas.

A plant has a genetic maximum potential, and your goal as a grower is to get as close to that as possible.

Topping a few times over the course of veg is plenty to bear the fruits of this method. Simply watch for apical dominance and top as needed! Let’s move onto a more advanced technique now.

Defoliation - Removing Fan Leaves To Let More Light In

We called topping the easiest technique there is, but defoliation is a really close second. Whereas topping involves cutting back shoots of growth, defoliation is strategically removing fan leaves from your plant.

You don’t want to make your plant bald - foliage is incredibly important. But, those huge fan leaves are likely doing more harm than good, and you can pluck them as you see fit!

This serves a few different purposes. For one, this will allow light deeper into your plant, since fan leaves can get really big and cover flower sites.

This also helps your plant spend energy on branching, lateral growth, and flower development - rather than on producing lush, green foliage.

And, defoliation is essential to help maintain decent air flow through your plant and your grow room.

If you’ve got a lot of plants crammed in a small grow space, defoliation eliminates leaf-to-leaf contact to a certain extent. This lowers the risk of powdery mildew, and other humidity-related issues.

Defoliation Is Another Ongoing Task

Defoliation should be used throughout your grow along with whatever other techniques you implement.

This is a pretty essential garden care task that you should undertake whenever you notice huge fan leaves are sucking the nutrients and disrupting light penetration in your grow.

FIMing - Topping With A Twist

It may sound crazy that people would purposefully “miss” their topping technique and trim off just ½ - ¾ of the actual node of growth, but that’s exactly what FIMing is.

This results in a substantial stress stimulus, but the plant will usually recovery faster since there is less damage to repair. While the plant repairs this site, vertical growth comes to halt - which is exactly what we’re after. The plant turns its attention to lateral growth, and other colas throughout the plant.

While topping can produce 2 colas per snip, FIMing can sometimes produce four colas per snip! This is why plenty of growers opt for FIMing over topping. Try both for yourself and see which one results in better flower and heavier harvests!

Super Cropping - Bending Branches So They Grow Horizontally

One of the more invasive and damaging high stress training techniques we’ll cover today is supercropping.

We have an entire guide on super cropping plants if you want the detailed lowdown, but we’ll just give a brief summary and explain why it’s such a powerful tool you can utilize.

With this approach, you won’t be cutting off any growth. Instead, you bend the branches down at a horizontal angle. This sounds pretty similar to low stress training, but there is a caveat - you wait until the branch has hardened off a bit more, and focus on damaging the tissue between your fingers.

Super Cropping - Bending Branches So They Grow Horizontally

This sounds crazy, but hear us out. When done properly, you can damage the interior of the branch without actually breaking it or rupturing anything on the outside.

The plant goes into damage control mode, and works to repair this damage. It overcompensates and produces a thick, knuckle like scar at the side of your bend & squeeze. The branch is then stronger than before, and capable of supporting big, heavy flowers.

But more importantly, you’ve created a horizontal canopy, and will produce a far bushier plant with more colas, and thus, a heavier yield.

Don’t Break Branches All The Way - But If You Do, Repair With Duct Tape

There is a fine line between bending the tissue and squeezing it between your fingers, and snapping a branch. You definitely don’t want to create any open wounds in your plant.

This is a welcome mat for pests and diseases to enter, and can result in too much stress for the plant to recover from - you may end up losing the branch.

But, don’t stress too much if you do. Simply duct tape the injury site, and you’ll be amazed at how resilient your plant is - it should be able to seal up the wound over time and recovery entirely!

Manifolding or Mainlining - Creating A Bush From The Start

A technique that combines a few different methodologies of plant training is manifolding. Some refer to this technique as mainlining, but whatever you call it, the premise is this:

You want to chop off lower growth that doesn’t receive any light, and create a flat canopy of huge colas. You accomplish this with a combination of LST, topping, and defoliation.

Simply grow your plant until it has one main cola, with two smaller ones on each side. This will likely be a couple weeks into veg.

Then, you eliminate the main shoot by topping it, and pull back the two side growths so that they are horizontal - essentially creating a flat line across your garden pot (or hydro system). Tie these shoots down.

As your plant recovers from this high level of stress, it will form colas along that flat line. These will continue to grow and you can top them as necessary, but your goal should be to create a “candelabra” candle holder shape.

Continue Cleaning Up Lower Growth Throughout

Over the course of the grow, you’ll continue eliminating any lower level growth beneath your canopy, only focusing on what can receive light from either the sun or your grow lights.

This is a more strategic technique than some of the others we’ve mentioned, and is far more involved.

But the extra work is worth it, as growers report record breaking harvests when implementing this method!

Integrating High Stress Training Techniques For A Heavy Harvest

Now, we’ve given an in-depth look into each of these HST techniques. But how do you actually implement them over the course of a grow to get the most bang for your buck?

Every grow is different, and some strains are going to respond better to certain forms of training than others. Some are more stress resistant, others will take longer to rebound - so be careful.

But, here is a sample training program you can implement into your next grow. Tweak it as needed to meet your grow room or garden conditions, but following this outline will result in a very well trained plant capable of producing a heavy harvest.

  • Start With Topping - in weeks 2-3, your plant will likely be ready for it’s first topping. Snip off that main shoot of growth, and wait a week for the plant to rebound.
  • LST Your Plants - In the 3rd or 4th week, depending on when you topped your plant the first time, you can LST your plants. By now those two shoots of growth should have taken off, and will be long enough you can tie them back down. You will be left with a relatively flat line for your canopy.
  • Super Crop Your Plants - Around week 5 of veg, your plant will have hardened off a bit and is ready to be super cropped. Carefully bend the branch down and squeeze the plant tissue, feeling the interior tissue give way beneath your fingers without actually breaking the outside of this tissue. This will not only help further create a bush like shape to compliment your LST, it also prepares your branches for some heavy buds by strengthening the joints of your branches.
  • Defoliation & Pruning The Rest Of The Way - After you’ve supercropped your branches, you have more or less done all the work necessary to create the shape of your plant. Now, you can simple defoliate as needed, and prune away any bottom growth that isn’t going to produce dense buds. This can be carried out through harvest.

Allow Your Plants To Rebound From Stress After HST

The name high stress training shouldn’t be taken lightly - some of these techniques really do a number on your plants.

You should be aware of this, and give the plants a good watering and feeding after a training session. This will help them bounce back from stress, especially if you’re using additives like silica or cal mag.

We also recommend leaving at least a week between training sessions. This will prevent you from overdoing it and stressing your plant out to the point it isn’t able to bounce back.

Final Thoughts On High Stress Training Your Plants

We want to leave you with a few parting thoughts on high stress training. As with all forms of garden care, ensure you're using clean, sterile tools.

And, you may need to undertake a longer vegetative period with high stress training than you would have liked.

This is because immediately following your training sessions, your plant will have to take some time to recover. Not a ton of growth will happen during this rebound. But rest assured, it will pay off come harvest day.

Now, all that’s left to do is grab whatever supplies you think you’ll need over the course of your grow and get to work! We carry all the plant training supplies you may need, including trellis, stakes, and ties.

We also carry garden shears to help you with topping and pruning. Hydrobuilder is the #1 online garden superstore, carrying everything you need from seed to harvest!

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