Low-Stress Training (LST) for Cannabis: A Step-by-Step Guide

Low-stress training (LST) means gently bending a cannabis plant’s stems and tying them down, without cutting anything, so the plant grows wide and flat instead of tall. A flat canopy puts more of the plant’s growing tips at the same distance from the light. It is the gentlest way to shape a plant, which is why it suits beginners and autoflowers.

This guide covers why bending works, what you need, how to do it week by week, and the mistakes to avoid. It is part of the CTU how-to-grow guide, stage 3: training.

Why bending a plant changes how it grows

A young cannabis plant puts most of its energy into the main stem’s tip. Plant scientists call this apical dominance: the growing tip at the top holds back the buds lower on the stem ^[1]. Left alone, many plants grow one tall main cola with smaller branches below it.

When you bend the main stem over, the old top is no longer the highest point. The side branches then turn upward and grow toward the light. Fruit growers use the same idea: orchard guides from Michigan State University Extension note that upright branches grow more vigorously and that branches bent toward horizontal slow their growth ^[6]. Plants also respond to repeated touching and bending by changing how they grow, a response called thigmomorphogenesis ^[5].

Light is the reason a flat canopy matters. In a University of Guelph study of indoor cannabis, dry flower yield rose in a straight line as the light at the top of the canopy increased, all the way up to 1,800 µmol·m⁻²·s⁻¹ ^[2]. Leaves shade the leaves and flowers below them, so the lower parts of a plant get less light ^[2]. Position matters for quality too: in a 2022 indoor study, total CBD concentration was higher in the top flowers (9.9%) than in the middle (8.2%) and lower (7.7%) flowers in that study ^[4]. Researchers in Israel found that changing the shape of the plant (pruning and opening up the canopy) made cannabinoid levels more even from flower to flower ^[3].

LST is the low-risk way to get some of that benefit at home: more tops, closer to the same height, under the same light.

What you need

• Soft plant ties. Rubber-coated garden wire, soft plant tie tape or wide twist ties. Avoid thin string or bare wire; they can cut into the stem as it thickens.
• Anchor points on the pot. Small holes drilled just under the pot’s rim, hooks, or a ring of wire around the pot. Fabric pots let you clip ties straight to the fabric.
• Plant tape. For splinting a stem if one cracks.
• A few minutes every two or three days. LST is many small adjustments, not one big one.

How to do LST, step by step

LST happens in the vegetative stage, while stems are still green and flexible. Stems get stiffer and woodier as they age, so make the big bends early and only small changes later.

1. Wait for a few sets of leaves. Start once the plant has a few nodes (the points where leaves and branches join the stem) and the main stem bends easily without creasing.
2. Bend the main stem. Hold the stem near the base with one hand. With the other, slowly bend the top over to one side until it is close to horizontal. Tie it to the pot rim. Go slowly; if you feel the stem resist, stop and tie it at a gentler angle.
3. Let the side branches rise. Over the next few days the side branches turn upward toward the light. The old top keeps growing too, now pointing sideways.
4. Tie down whatever grows tallest. Every two or three days, find the branch that has grown above the rest and bend it down and outward. The goal is a flat, even top with the branches spread like the spokes of a wheel.
5. Move ties as the plant grows. Loosen or reposition ties so they never pinch the stem. A tie that was loose last week can be tight this week.
6. Clear the floor of the canopy. Small shoots at the bottom that will never reach the light can be left alone or removed. Removing them is pruning, not LST, and it is a separate choice (see the pruning guide).
7. Ease off in flower. After you switch a photoperiod plant to flowering (growers usually do this by changing to 12 hours of light and 12 of dark ^[8]), the plant keeps stretching for a while. Keep making small adjustments to hold the canopy level, then stop bending once the buds are forming.

LST compared with other training methods

Many growers combine LST with topping. Our guides to topping, SCROG and sea of green cover those methods, and Cannabis Plant Training: 7 Methods compares them all.

LST on autoflowers

Autoflowering cannabis is photoperiod insensitive: it starts flowering on its own as it ages, not when the nights get longer ^[7]. That leaves a short vegetative window. Because LST removes nothing, there is no wound for the plant to recover from, so it fits that short window better than methods that cut the plant. Start bending earlier than you would on a photoperiod plant and keep the bends gentle.

Common mistakes

• Bending too far, too fast. A stem bent sharply can crack or fold. Bend in stages over several days.
• Ties that cut in. Check ties every few days; move them as stems thicken.
• Starting too late. Old, woody stems resist bending and crack more easily. Do the main shaping in early veg.
• Forgetting the tallest branch. One unchecked branch becomes the new main cola and shades the rest.
• Training in flower. Big bends after buds have formed can damage flower sites. Make only small adjustments after the switch.

If a stem cracks: don’t cut it off. Line the two sides up, wrap the crack firmly with plant tape, and support it with a tie so the joint can’t move, then check it over the next few days.

Check your state’s home-grow rules first

Home growing is legal only in some states, and most that allow it limit the number of plants, how many can be flowering at once, and where they can be grown. Check the rules for your state on our state cannabis law pages before you start.

Learn the whole grow, step by step

LST is one stage of a full grow. The CTU how-to-grow guide walks through all eight stages, from germination to curing, with our deepest article on each. To learn it properly, with lessons on training, lighting, feeding and harvest, see the Cannabis Growing course (now includes Growing Autoflowers), or try the first lesson free.

Sources

1. Barbier, F.F., Dun, E.A. & Beveridge, C.A. (2017). “Apical dominance.” Current Biology 27(17): R864–R865. doi.org/10.1016/j.cub.2017.05.024
2. Rodriguez-Morrison, V., Llewellyn, D. & Zheng, Y. (May 11, 2021). “Cannabis Yield, Potency, and Leaf Photosynthesis Respond Differently to Increasing Light Levels in an Indoor Environment.” Frontiers in Plant Science 12: 646020. University of Guelph. doi.org/10.3389/fpls.2021.646020
3. Danziger, N. & Bernstein, N. (Sep 2021). “Shape Matters: Plant Architecture Affects Chemical Uniformity in Large-Size Medical Cannabis Plants.” Plants 10(9): 1834. doi.org/10.3390/plants10091834 · and Danziger, N. & Bernstein, N. (2021). “Plant architecture manipulation increases cannabinoid standardization in ‘drug-type’ medical Cannabis.” Industrial Crops and Products 167: 113528. doi.org/10.1016/j.indcrop.2021.113528
4. Crispim Massuela, D. et al. (Jan 2022). “Impact of Harvest Time and Pruning Technique on Total CBD Concentration and Yield of Medicinal Cannabis.” Plants 11(1): 140. University of Hohenheim. doi.org/10.3390/plants11010140
5. Braam, J. (Feb 2005). “In touch: plant responses to mechanical stimuli.” New Phytologist 165(2): 373–389. doi.org/10.1111/j.1469-8137.2004.01263.x
6. Michigan State University Extension (2013). “Bend branches now to encourage flower bud initiation in high density apple orchards.” www.canr.msu.edu/news/bend_branches_now_to_encourage_flower_bud_initiation_in_high_density_apple_ · and “Training apple trees in tall spindle during developing years.” www.canr.msu.edu/news/training_apple_trees_in_tall_spindle_during_developing_years
7. Toth, J.A., Stack, G.M., Carlson, C.H. & Smart, L.B. (Sep 21, 2022). “Identification and mapping of major-effect flowering time loci Autoflower1 and Early1 in Cannabis sativa L.” Frontiers in Plant Science 13: 991680. Cornell University. doi.org/10.3389/fpls.2022.991680
8. Peterswald, T.J. et al. (Feb 27, 2023). “Moving Away from 12:12; the Effect of Different Photoperiods on Biomass Yield and Cannabinoids in Medicinal Cannabis.” Plants 12(5): 1061. doi.org/10.3390/plants12051061

All sources checked Oct 26, 2026. Plant-growing information only; this page makes no health claims.

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