Low Stress Training (LST) is a technique where the main stem and branches of a plant are gently bent and secured to alter their growth direction. This manipulation does not involve cutting or wounding the plant, making it ideal for autoflowering varieties. Timing is critical for autoflowers because they operate on a fixed biological clock, automatically transitioning to the flowering phase regardless of the light schedule. Autoflowers have a short, non-negotiable vegetative period, meaning any time lost to recovery from stress directly impacts the final yield. Precision in when to start and stop LST is paramount to maximize structural development.
Understanding Autoflower Growth Stages
The life cycle of an autoflower progresses rapidly, defining a narrow window for training. The initial seedling phase typically spans the first one to three weeks after the seed sprouts. During this time, the plant is fragile, focusing on establishing a root system and developing its first few sets of true leaves. Attempting LST during this delicate stage risks irreparable damage and growth stunting.
The plant then enters a brief but vigorous vegetative phase, usually beginning around week two or three. This is when the plant rapidly increases in size and structure, adding new nodes and branches. Autoflowers typically initiate pre-flowering between week three and week five, signaling the end of their structural growth period. This short vegetative stage creates a small window where LST can be effective without causing detrimental stress.
The Optimal Timing for Initial Bending
The precise moment to begin Low Stress Training is determined by the plant’s structural development, not a strict calendar date. The optimal indicator is when the autoflower has developed three to five true nodes, which usually corresponds to the start of the third week from sprout. At this size, the main stem is sturdy enough for gentle manipulation but remains flexible, reducing the risk of snapping.
Starting LST at this stage allows time to redirect the plant’s energy before flowering begins. The goal of the initial bend is to gently pull the main stem down towards a horizontal position (45 to 90 degrees). This action breaks apical dominance, the plant’s tendency to prioritize vertical growth. Keeping the main stem low redirects growth hormones to the side branches, encouraging them to grow upward and form multiple primary bud sites. Secure the bend using soft ties or coated wire anchored to the container, ensuring the base of the stem is supported to prevent uprooting.
Continuing and Adjusting Training
After the initial tie-down, LST becomes an ongoing maintenance process throughout the short vegetative period. The side branches, now receiving more light and hormones, will immediately stretch vertically toward the light source. These new shoots must also be gently bent and tied down to maintain an even, flat canopy.
Daily adjustments are necessary because autoflowers grow rapidly, and new growth must be secured before the stems harden. This continuous manipulation ensures that all potential bud sites are exposed to the same light intensity, maximizing canopy efficiency. This maintenance typically continues until the plant begins its pre-flowering stretch, often around the end of week four or the start of week five. Once vertical growth slows and the plant focuses on bud production, indicated by the appearance of the first pistils, LST efforts should cease to avoid stressing the plant during flower development.
Common Mistakes in LST Timing
Mistakes in LST timing can significantly impact the plant’s health and final yield due to the autoflower’s compressed life cycle.
Starting Too Early
Starting the training process too early, when the plant is still a small seedling, can easily damage the fragile primary stalk or the underdeveloped root system. This premature stress often results in stunting, causing the plant to pause growth to recover. This effectively shrinks the already limited vegetative window and leads to a smaller final size.
Starting Too Late
Waiting too long to initiate LST is the most frequent error for new growers. If training is delayed until week four or later, the main stem and lower branches begin to harden and become woody. Attempting to bend a rigid stem dramatically increases the risk of snapping or cracking the tissue, requiring recovery time the autoflower cannot afford. A late start also leaves insufficient time for secondary branches to develop into robust colas before the plant commits fully to flowering.