Low Stress Training – Bending your way to bushy plants and high yields

If let untouched, a cannabis plant usually has some kind of christmas tree shape. This is okay for a plant in nature. The sun will reach every part of the plant equally over the course of the day.

This condition is different in a tent. The plant will not get hit by parallel light, but rather by point light from a low distance. (In the case of HPS or CMH lights. Even the common LED lights are pretty limited in regards of their light emitting cone.)

One important rule for light: Radiance – the amount of light a leaf receives is divided by 4 when the distance is multiplied by two ( R ~ 1/r²). This counts for every light out there.

On the other hand, light height is determined by the height of the plants main bud. The cannabis plant usually builds up one main bud which will grow a lot higher than the rest of the plant. To determine light height depending on a main bud will automatically decrease the amount of light the side buds can potentially get!

So the main goal will be the following: Have all buds to be at the same height, so every bud can receive an equal amount of light. If you then have an aerial light source (Quantum board or a good amount of COBs) you will have the perfect light distribution in your tent. In this chapter we deal with the canopy of the plants and Low Stress Training (LST).

What is Low Stress Training?

Stress is induced if a plant is exposed to an unnatural change in its environment. Most of these changes are unwanted and should be adressed accordingly, other stressfactors can be applied and will result in the predicted outcomes. LST is one of the latter.

The training aspect of the whole operation is a result of the change you induce: The plant will react to the stress and will need time and energy to do so. The most common forms of LST involve some kind of obstacle to grow around or to deal with.

The usual way to apply LST to a plant is to bent her to the side to encourage horizontal growth. This causes the plant to distribute more energy to the secondary tops and will result in a more uniform bud structure. You will lose the uniqueness of the main top, but the net yield should be higher in the end. This also brings us to the main reason of LST: You can actually bring your light lower! This is good for every bud and will result in an even more increased yield and better quality of the product. Buds develop differently depending on its place on a branch. Lower buds will develop less good and will take longer to be ripe.

cannabis flower pre harvest
A Critical plant that has been exposed to LST constantly. The buds are all of the same height and roughly the same size.

When do you expose the plant to training?

As soon as the plant has established a strong rootsystem you can start. But the best indicator is to count the nodes of a young plant.
The nodes are created one after another from the main stem. The top of the plant is the main node, and under this main the plant will create second and third nodes. Since these secondary nodes are developed after the mainstem, they will always stay behind the main top. The moment you see the little nodes form, you can start the training. You can also apply LST a few weeks into flowering. Just make sure the stems are still bendy and won’t just break. The flowering stretch is still considered vegetative growth and the plant will still be able to be trained. After this, you should stop and just watch the her thrive.

Plants as little as this can be exposed to LST. The first hook at the stem prevents the plant to grow completely tilted. The other hooks bend down the main stem, while the second and third nodes get exposed.
second to third rotation of cannabis training lst
LST can look messy at first: It can also be used to spread out a plant. Every side branch of this Francos Lemon Cheese, Green House Seeds, will be a new main top in the end. You can also observe where fan leafs got removed to expose the stems to more light and air.

The Pros Way of LST: Gardening Metal Hooks

The most common way involves gardening wire which gets attached to the stems. This is pretty clumsy and you can hurt your plant very bad if done wrong. The pro makes use of gardening metal hooks that can be ordered online for cheap. Look for a secondary node you want to expose, bend away the stem and everything above it, so it gets hit by direct light. If there is still a fan leaf casting a shadow over the secondary node, you want to remove this fan leaf in the next step. THATS ABOUT IT!

  • Let it be: Keep the hook in there for the rest of the grow or replace it with a hook you set up to bend the main stem over one more time. Removing the hooks before flowering or in flower will result in a plant that grows inwards. And this is exactly the opposite of what you want to achieve with LST.
  • Recovery time: Let the plant recover from LST before you do it again. LST is not inherently harmful in comparison to super cropping or topping / fimming, but still stressful. Usually a plant recovers in about three days from LST and can be bothered with it again after it.
  • Bend it, don’t break it: Don’t try this if the stem is already rigid. The older the stem, the less bendy it will be. Be careful! If you break the stem it is always bad and the plant needs much more recovery from a broken stem.
  • Don’t use force: I lost a number of plants to this already. Less is more here, dont push with full force. The plant won’t tell you when its enough. It will just break.
  • Don’t use sharp wires: The plant will cut itself resulting in a bad injury. It is not inherently lethal but in the worst case your plant will just grow around the injury and the wire and is exposed to infections. This could end bad!
  • Check the plants: The recovery time is pretty short. Watch your plants closely and you will figure out the best way to use LST for you very fast.
Timelapse of a plant that got exposed to LST. This animation recorded the 3 days of recovery after the hooks have been setup. You can also see, that fanleafs that pointed to the center of the plant got removed.

LST and Autoflowering Cannabis

There is a big discussion going on about training autoflowers. I tried several training methods myself on autoflowers. Since the recovery time from LST is so short, there is plenty of time to do this to your autoflowers. Autoflowers are not vastly different from non-auto plants. Autoflowers do not want to bothered with LST while she is busy building up the sweet buds. Start as early as you can, and keep a close look on your plant.

training of an autoflowering cannabis plant
Alien vs. Triangle Autoflower from Mephisto Genetics that got exposed to LST. Its pretty much possible to do this, but with limits! Start as early as you can, and look for the signs of flowering.
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9 thoughts on “Low Stress Training – Bending your way to bushy plants and high yields”

  1. First time auto-grower.
    This is super helpful and I am excited to try last on my Train Reck autos.
    Growing indoors in Canada’s frigid winter is a challenge.
    I heat with wood, the temps in my house can dip to 14C by morning.
    Thinking heat pad and humidifier in my immediate future.

    1. 14C is quite a challenge, but everything above 11C should not be lethal. Higher temps would be better ofcourse! 🙂 Happy growing!

  2. Great article! Very helpful.

    I just have to comment on the 2nd last picture, the time-lapse one. I was listening to some “acid chillout” – music, and started to wonder if there was psilocibyn in my coffee as I encountered that picture, moving absolutely perfectly synced with the music making it quite trippy 😀

  3. If you can keep it around that temp (during lights out) you can grow really purple buds. I grew some purple kush and I’ve never seen colours like that before.

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