Cannabis Growing 101: What is Low Stress Training?

LST training
By Fred Hernandez Updated July 10th

Fact-checked by Alexandra Arnett, MS

Growing your own cannabis offers several benefits, whether you’re growing in your closet or a large commercial facility. From having control over the cultivars you grow to the satisfaction of consuming something you've nurtured from seed, the process can be deeply rewarding. 

However, the journey to harvesting a robust yield can be complicated. For many, navigating the different growth techniques can be daunting, especially given that some methods, if applied incorrectly, can be detrimental to the plant.

That's where low-stress training (LST) comes into play. Unlike other more invasive techniques, LST ensures that your cannabis plants grow optimally without causing them harm. 

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What Is Low-Stress Training?

Low-stress training (often abbreviated as LST) is a tried and true method aimed at maximizing the yield of cannabis plants without causing them undue stress. The technique involves bending and securing the branches and stems of the cannabis plant, breaking the plant's natural tendency known as apical dominance. But why is this beneficial?

Cannabis plants generally exhibit a Christmas tree shape, characterized by a dominant central stem that develops a large cola, with smaller side branches and buds forming beneath it. By employing LST, growers can manipulate the plant to break this apical dominance, creating a flatter canopy. This even canopy allows for optimal light distribution, which, in turn, promotes more bud sites and larger yields.

One of the standout features of LST is its gentle approach. Unlike "high stress" methods that involve more severe actions like cutting off the plant's primary growth tip, LST is considerably more delicate. This means that the risk of stressing the plant is minimized, and there's little to no waiting period for the plant to recover. This gentler nature ensures that plants respond favorably to LST, ultimately rewarding growers with robust, sizable buds.

Why Doesn’t LST Harm the Plant?

The key distinction between LST and other plant training techniques lies in the phrase "low stress." While certain training methods involve more aggressive actions, such as cutting or topping, which can stress the plant and require a long recovery period, LST does not. Instead of cutting or injuring the plant, LST involves gentle bending and tying down of branches.

Since there's no inherent pruning or trimming involved in LST, plants are not subjected to any sudden changes or damage. They do not need an extensive recovery period, and they continue to thrive and grow without interruption. This continuity is crucial because it means that while the plant is being trained to grow in a more beneficial shape, it isn't facing any harm or setbacks.

When done correctly, using the appropriate materials, like rubber-coated plant ties, and avoiding harsh strings that can damage stems, LST ensures that plants remain healthy. Plus, any minor mishaps, like a bent branch, can be easily fixed without causing long-term damage.

How Does LST Training Work?

what is LST training

LST is a technique commonly used in cannabis cultivation to maximize the plant's yield and efficiently use the available growing space, which is especially helpful when you’re growing in tight quarters. By understanding its methods and benefits, growers can significantly increase their harvests.

What’s the Theory Behind Low Stress Training

LST is rooted in the principle of gently manipulating the plant's branches to encourage a more horizontal growth rather than their natural vertical tendency. This is achieved by bending branches down so that new growth from these branches grows upwards, creating an even canopy filled with equally tall branches. 

The concept of nodes is essential here, as these nodes will produce new vertical growth. The practice of LST has been used in various forms of agriculture for thousands of years. In cannabis cultivation, it is often combined with other techniques, such as high-stress training (HST), for optimal results.

How Does It Increase Cannabis Yields?

There are several reasons why LST increases cannabis yields:

  • Improved Light Exposure: One of the primary benefits of LST is maximizing light efficiency. With a level canopy, light can be distributed evenly across all bud sites, allowing the lighting fixture to be closer to the plant. This ensures that the top of the cannabis plant receives higher light intensity, leading to the growth of larger buds.
  • Breaking Apical Dominance: In a cannabis plant, the central stem usually grows more dominantly than the lateral branches. By using LST, growers can break this apical dominance, allowing the lateral branches to receive growth-stimulating chemicals. As a result, lateral shoots grow larger and yield more.
  • Increased Airflow: LST helps spread out branches, ensuring better airflow. This is crucial because tightly packed branches can trap stale, moist air, leading to mold issues. By allowing better airflow, the risk of mold and other diseases is reduced.

How Does It Change the Shape of the Plant?

By using LST, the plant adopts a more spread-out and bushy appearance, as opposed to its natural tall and narrow shape. This manipulation allows growers to maximize the plant's footprint within their growing space. 

​​When applying LST, it's essential to use the right materials. Tools like coated wires or LST training clips are beneficial, and SCROG nets – usually made of polycarbonate or plastic – help manage and maintain the plant's shape.

It's crucial to note that while LST is an excellent tool for managing the growth and shape of regular and feminized cannabis strains, it should be the only training method used for automatic cannabis strains. This is due to their shorter growth cycle and limited recovery time.

Advantages of LST Growing

  • Optimized Light Distribution: By flattening the canopy and breaking apical dominance, LST ensures that all areas of the plant receive optimal light. This not only promotes growth in areas that might otherwise be overshadowed but also increases viable bud sites. This results in larger yields.
  • Minimal Equipment Required: One of the appealing aspects of LST is that it doesn't require any major changes to your growing setup. The technique only requires some basic tools, like rubber-coated plant wire, thin stakes, a hand drill, and electrical tape, to be effectively implemented.
  • Less Stress on Plants: As the name suggests, LST is a "low stress" method, meaning it's gentler on plants compared to "high stress" techniques like topping. There's minimal risk of over-stressing the plant, leading to quicker recovery and adaptation periods.
  • Flexibility and Control: LST allows growers to influence the shape and direction of their plant's growth, giving them more control over the plant's development. This can be particularly beneficial for those growing in confined spaces or those looking to maintain a low-profile crop.
  • Good for Outdoor and Indoor Growing: Contrary to some beliefs, LST isn’t restricted to just indoor cultivation. It originally started as an outdoor cultivation method. For growers in regions with less sunshine, like parts of Northern Europe, outdoor LST can significantly augment yield during the short summer season. 
  • Discreet Growing: LST can help in maintaining a discreet outdoor cultivation, as plants trained to have a flatter canopy will likely attract less attention compared to a towering, untrained cannabis plant.

While LST is considered low stress, there is still the potential to harm the plant if not done correctly. Using unsuitable ties, like regular string, can cut into the stems, causing more harm than good. Additionally, growers should be cautious when bending branches to avoid snapping them.

However, if a branch does break partially, it can typically be mended with electrical tape and will heal over time. Growers should aim to be gentle and patient and periodically adjust the ties and do some necessary trimming as the plant grows to ensure an even canopy.

LST Cannabis Growing: What You'll Need

When performing LST for your cannabis plants, making sure you have the right tools and materials on hand is crucial. Not only will the correct equipment help in the successful training of your plants, but it can also protect them from potential harm.

Tools and Supplies

  • Rubber-coated plant wire/soft plant ties: The choice of tie is crucial. When securing branches, opt for rubber or protective-coated wires. These are gentle on the plants, preventing any cutting or damage to the growing branches. Avoid thin, uncoated metal wires, as these can harm the plants by cutting into the branches.
  • Thin wooden/bamboo stakes: These stakes provide additional support and guidance for the plant's direction of growth during the LST process.
  • Small hand drill: If your growing container doesn't already have holes, a hand drill can be used to create them. These holes serve as anchor points for the plant ties.
  • Electrical tape: In the event of accidental snaps or breaks during the bending process, electrical tape can be a lifesaver. It allows growers to patch up any minor damages, enabling the plant to heal over time.
  • Binder Clips: For those who prefer not to drill holes into their containers, binder clips are a handy alternative. Attach them to the lip of your container and use them as anchor points for your ties.
  • LST Training Clips: A newer tool on the market, these clips assist in directing the plant's growth. They are particularly useful as the plant grows, helping in adjusting the direction of branch growth.
  • SCROG nets: Some growers use "screen of green" (SCROG) nets alongside LST, especially when aiming for optimal light exposure across a flat canopy. These nets are often single-use, as removing them post-harvest can be tricky. Always ensure you dispose of any excess netting appropriately to protect wildlife. And remember, while it might be tempting to use string or twine, these materials can retain moisture, which can increase the risk of mold growth, thereby posing risks to your cannabis plants.

Costs and Budgeting

The good news is that LST, especially in its simplest form, doesn't demand a significant financial investment. Most of the basic tools and materials, such as plant ties and stakes, are reasonably priced. 

However, for those looking to optimize their grow setup with more specialized tools like LST training clips or SCROG nets, there might be some additional costs. Always keep in mind that investing in quality materials upfront, such as quality soil, seeds, and lights, can lead to better results and potentially higher yields in the long run.

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When to Start Low-Stress Training

The ideal time to start LST, similar to other training methods such as topping, is once your cannabis plant comfortably enters its vegetative stage. At this point, the plant has had the chance to develop a few strong nodes, and its stems are still pliable, making it easier and safer to bend and shape them. 

As a general guideline, starting LST as early as possible in the vegetative stage is the best route. This not only sets your plants up for more efficient light exposure, leading to improved bud development, but also helps to break the plant's inherent apical dominance. This encourages a more even and flat canopy.

While LST is a potent technique, there's a timeframe when its application might do more harm than good. Once the plant transitions fully into its flowering phase, its stems become considerably more rigid. 

At this point, any attempt to bend or manipulate the plant carries the heightened risk of snapping a branch, especially one growing heavy buds. Because of this, it is advised against introducing LST during the advanced flowering phase to prevent potential damage to the plant and its yield.

How to Use Low-Stress Training on Your Plants

how to use low-stress training

Preparing Your Growing Container

Before you begin with the low-stress training process, ensure your container is ready:

  1. Drill Holes for Ties: Drill several holes around the rim of your growing container. This will be used to secure the stems and branches in place using ties.
  2. Use Stakes for Support: Consider using thin wooden or bamboo stakes, roughly 11-12 inches in length, to provide additional support.
  3. Have Electrical Tape on Hand: Accidents can happen during the training process. If a branch snaps or breaks, electrical tape can be used to patch it up, allowing the plant to heal.

Steps for Low-Stress Training Cannabis Plants

  1. Break Apical Dominance: Start by gently bending the main stem toward the rim of the container. Using soft plant wire and the pre-drilled holes in your container, securely tie the stem in place. This will flatten the canopy and promote horizontal growth, enabling light to reach more bud sites and potentially increase the yield.

    Tip: Some growers first top the main stem and then bend the secondary shoots out to the side. This gives the plant a "spider" shape. However, even with standard LST, light defoliation can be beneficial to increase light penetration.
  2. Shape and Maintain Your Plant: Ensure the canopy remains flat so that no branch is taller than the others. It's important to bend the shoots outward, away from the main stem. If you accidentally snap a branch, it can typically be fixed with electrical tape. It will need about a week to heal. Remember, LST requires consistent maintenance. As your plant grows, you'll need to adjust your ties to maintain the desired shape.
  3. Choose the Branch or Stem to Train: Examine your plant, and decide which branches or stems you'll be training. Ideal candidates are long, fairly straight, with an abundance of leaves.
  4. Tie Down the Branch or Stem: Using a soft material like twine, tie down the chosen branch or stem. Make sure there's sufficient slack and that it's not tied too tightly. Optionally, weights such as stones or coins can be used to bend the branch or stem further.
  5. Monitor and Adjust: After tying down the branch or stem, observe its position and make adjustments if necessary.
  6. Repeat: Continue this process as required until your cannabis plants achieve the desired shape.

By following these steps, you can efficiently implement LST techniques to optimize the growth and yield of your cannabis plants. For successful LST, patience is key; always handle your plants gently and adjust as necessary to achieve the best results.

Perfecting the LST Technique

Low-stress training is a practical method for optimizing cannabis growth and maximizing yields. This guide offers a structured approach to LST, but successful implementation relies on careful observation and consistent adjustments. With diligence and patience, growers can effectively use LST to improve their plants' health, shape, and productivity, enhancing their overall cultivation experience.

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The information in this article and any included images or charts are for educational purposes only. This information is neither a substitute for, nor does it replace, professional legal advice or medical advice, diagnosis, or treatment. If you have any concerns or questions about laws, regulations, or your health, you should always consult with an attorney, physician or other licensed professional.

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