Low-Stress Training (LST) is a gentle horticultural method used to manipulate a plant’s shape without causing significant damage or interrupting its growth cycle. This technique involves carefully bending and securing the main stem and branches to encourage horizontal development rather than vertical growth. Autoflowers are unique cannabis strains that transition to the flowering stage based on their age, typically around three to four weeks, regardless of the light cycle they receive. Applying LST to these fast-growing plants is a way to maximize their potential within their short lifespan. This guide details how to effectively combine the training method of LST with the specific biological timeline of an autoflower to achieve a more productive plant structure.
Why Low-Stress Training Benefits Autoflowers
The primary advantage of Low-Stress Training for autoflowers is that it allows growers to increase the number of primary budding sites without imposing a lengthy recovery time. Unlike photoperiod cannabis strains, which can remain in the vegetative phase indefinitely to recover from high-stress techniques like topping, autoflowers have a fixed, rapid clock. Any significant shock or injury risks stunting growth right before the plant begins its final flowering stage, leading to diminished yields.
Cannabis naturally exhibits apical dominance, a phenomenon where the highest point of the main stem receives the majority of the growth hormone auxin, resulting in a distinct Christmas tree shape with one large central cola. By gently bending the main stem sideways, LST effectively breaks this dominance, signaling the plant to redistribute auxin evenly to the lower side branches. These lower shoots then accelerate their growth, stretching upward toward the light and developing into multiple, equally large secondary colas. This manipulation creates a level, uniform canopy, ensuring that all potential bud sites receive optimal light exposure for robust flower development.
Timing and Preparation for Training
The timing for initiating LST on an autoflower is crucial because of its short vegetative window, often only three to five weeks long. Growers should begin the training process as soon as the plant has developed three to five true nodes, which typically occurs around the third week after germination. Starting too early risks damaging the fragile, thin stem, while waiting too long means the plant may already be hardening its tissue, making the stem less pliable.
Before starting, gather the proper materials to ensure the plant is not damaged during the process. The ties used must be soft and pliable, such as specialized rubber-coated garden wire or soft plant ties, to prevent them from cutting into the stem as it thickens over time. Avoid using thin string, fishing line, or uncoated wire, as these can easily girdle or slice the expanding stalk. It is also helpful to prepare the container by drilling small holes around the rim of plastic pots to serve as secure anchor points for the ties.
Step-by-Step Low-Stress Training Application
The physical application of LST begins with identifying the main stem and the intended direction of the bend. The goal is to gently bend the main stem so that its growing tip is positioned parallel to the surface of the growing medium, ideally at a 90-degree angle from its original vertical position. First, secure a soft tie to an anchor point near the base of the plant to provide stability and counter-tension during the bend.
With one hand supporting the base of the stem to prevent the plant from pulling out of the soil, use the other hand to slowly arc the main stem over in the desired direction. The bend should be gradual and gentle; the stem should not be creased or snapped, only redirected. Immediately secure the bent stem using a second soft plant tie, fastening it to one of the anchor points on the pot rim. The newly positioned apex should now be lower than the side shoots, which will naturally begin to turn and grow upward toward the light source within a day or two.
The immediate result of this process is that the lower nodes, previously shaded, are now exposed directly to the grow light, promoting the desired vertical growth from these secondary branches. This initial bend is the most significant step, as it forces the plant to shift its growth pattern from a single-cola structure to a multi-branch, level canopy. The tie should be firm enough to hold the stem in place but loose enough to prevent constriction as the stem expands in diameter.
Adjustments and Continuous Canopy Management
Continuous management is necessary to maintain the desired flat canopy. Because autoflowers grow quickly, daily observation is beneficial to catch and redirect new growth tips that begin to dominate the canopy. Any shoot that grows significantly taller than the rest of the canopy should be gently bent and tied down to the rim of the pot or a training stake, ensuring all tops remain at a relatively even height.
As the plant continues to develop, the ties holding the main stem may need periodic adjustment to prevent them from digging into the thickening tissue. This ongoing process ensures the side branches continue to receive maximum light and develop into substantial colas. LST should generally cease once the plant is well into its flowering stage, typically around week five or six, or when the plant stops growing vertically and focuses solely on bud production.
If a stem accidentally snaps or splits during a bend, it is possible to recover the plant by immediately supporting the injury. A small piece of electrical or medical tape can be wrapped around the damaged area to act as a splint, allowing the plant to heal and continue growing. Maintaining an open structure also involves managing foliage, so occasionally tucking large fan leaves beneath new growth can improve airflow and light penetration to the developing bud sites.