How To Do Low Stress Training (LST) on Cannabis Plants

Low stress training has been used in agriculture for centuries and is one aspect in the process of making bonsai trees. As a very easy to perform technique, LST is now widely recognised across the cannabis industry for its advantages in the grow room.

A cannabis plant's structure is normally tall, with one long cola that extends past a number of lower, surrounding branches. These lower branches do not have as much access to light and often end up producing smaller buds. LST can help to solve this 'problem' and we want to show you how. This article teaches you how you can use low stress training to get the most out of your space without hurting your ladies.

What is Low Stress Training (LST)?

Low stress training (LST) is a technique used by growers to manipulate the shape and size of their cannabis plants by bending and tying branches to increase efficiency and yields. Performing LST results in a short but wide plant structure with a flat canopy, which means buds can make better use of the light and space available to them. 

Although commonly used together, LST does not wound a plant like high stress techniques (HST) such as topping or defoliation do. It is a gradual process that does not involve cutting and is more about guiding the plant rather than removing foliage.

Benefits of LST

Whether one is growing indoors or outdoors, there are a few reasons why you might choose to apply training techniques to your garden. Let's take a look at some of the benefits of LST and how it could improve your grow.

• Bushy/Wide Plants - Less spacing between internodes because plants do not need to stretch as far to receive light.
• Efficient Use Of Space - Plants in grow rooms that have limited space or low ceilings benefit from LST.
• More Exposure To Light - Photons are distributed more effectively across the canopy. Lateral flowers receive the same amount of light as the main cola, resulting in evenly sized buds.
• Higher Yields - More access to light means larger harvests.
• Easy to Perform - The concept is simple to understand. Applying LST is a slow process that involves daily maintenance.

How To Do Low Stress Training

Low stress training is simple to do provided you use the correct materials. Fortunately, LST isn't complicated and just requires consistency on your part. You need to be constantly making adjustments to the positioning of branches so they grow in the right direction and end up being the same height.

Growers will often 'top' their cannabis plant before starting LST which involves snipping off the newest shoot of the main stem. Topping breaks the upward growth pattern and helps to reduce plant height so lateral branches have a chance to catch up in height.

A cannabis plant focuses growth at the top bud through a hormone called auxin, which determines the vertical structure of the main cola. This means the goal of LST is to manipulate the plant so auxin is distributed more evenly across the canopy, creating more top buds. 

LST should be performed during the vegetative stage, and can begin as early as you want once the plant has a few sets of leaves. The plant will grow regardless of whether we do LST or not, so essentially we are just giving it a path to follow. Growth may be slightly slower, but the point is to increase light distribution and bud production, which is worth the effort. 

5 Steps to Perform LST on Cannabis Plants:

1. Consider how your plants should look. Think about how you want the final structure to be after LST. Your space might require the structure to be wide but narrow, or maybe you have a square grow tent that you are trying to fill.
2. Use garden wire or soft ties with a flexible plastic coating for holding branches in place. String or fine wires can cut into the stem under the tension from tying branches down.
3. Tie the tops of plants down first. Position each upper branch to be at roughly the same level as the lower shoots by tying it down. Be gentle and do not force branches if they look like they might snap. You can always manipulate them further the next day.
4. After 24 hours the tops of the branches should be facing upwards again. Repeat Step 3. Lower branches may need tying down as well if they are growing too tall.
5. Continue to adjust daily until the desired shape and size have been achieved. You can keep tying down branches/manipulating until the canopy is nicely filled with tops.

If LST has been applied properly during vegging, the canopy will be levelled by flowering so it is not really necessary to do further manipulation. You may need to do additional training during the explosive stretch at the beginning of flowering, so keep an eye out on the canopy and make small adjustments if needed.

It is not recommended to use LST after the first 2 or 3 weeks of the flowering phase because plants need to focus their energy on bud production. Stems are more rigid during flowering, and there is a higher risk of them snapping if they are bent, which would affect the overall yield. 

Low Stress Technique (LST) by MELs_Garden from GrowDiaries

Tips for Performing LST

If you are thinking about trying LST, it is a good idea to prepare your containers or pots before starting the grow. Planning ahead can give you an idea of how you might want to tie branches down or support growth along the way.

Pots - Holes can be drilled around the rim of the pot and used to hold branches in place using soft ties. Alternatively, you can use bamboo sticks or a wire ring fixed around the edge of the grow medium or on the outside of the pot.

ScrOG - This technique uses a growing net to keep plants positioned at a certain level. Branches can be 'held down' by the net or fed through it to even out the canopy.

Choose plants that can handle LST - Some strains are better suited to training techniques. Select resilient plants that are not prone to difficulties when put under stress.

Don't worry if a branch snaps when you bend it. Cannabis plants can survive this type of damage unless the branch has completely broken off. Bandage the wound with masking tape, give it some support, and it should heal (and possibly be even stronger than it was before).

Fastbuds solo

Conclusion

If you know your strains well, trying some low stress techniques in your garden can definitely pay off. As well as giving you full control over the size and shape of your garden, you are able to harvest even more big buds at the end of it, making it a great practice for any horticulturalist.

Did you find this article useful? Share your thoughts and ideas about low stress training in the comments section below!

External References

Apical dominance. Current Biology. - Barbier, Francois & Dun, Elizabeth & Beveridge, Christine. (2017).

Auxin and Sexuality in Cannabis sativa. Physiologia Plantarum. - Heslop‐Harrison, J. (2006)

This article was updated September 2020.