Cannabis Training Techniques
Training is the practice of shaping a cannabis plant so that the light it receives is used efficiently — converting what would have been a single tall cola into a wide, even canopy with many flowering sites. The general principles come from horticulture and arboriculture, where pruning and structural shaping are well studied, but the specific techniques used by cannabis growers — topping, low-stress training, and screen-of-green — are established grower practice rather than the subject of a single research paper. Understanding what each does, when it helps, and how much stress it adds is what separates a deliberate trained plant from an accidental one.
The shared principle behind all training
Every training technique works toward a similar goal: breaking the plant's natural habit of growing as a single dominant vertical column, called apical dominance. The plant concentrates its energy in the topmost shoot, and training redistributes that energy to the many side shoots below. On a completely untrained plant, the light that reaches the lower branches is poor, so most of the yield concentrates in one top cola. By exposing more branches to usable light, training produces multiple, similarly sized flowering tops instead. The general importance of this shaping — pruning to regulate plant form and improve light interception — is well established in horticultural practice, even if the specific cannabis methods are passed down as grower technique.
Topping — a cut, a permanent change
Topping is the removal of the main growing tip above a node, usually early in vegetative growth when the plant has several nodes. Because the dominant shoot is gone, the two side branches at the node below the cut become the new leaders, turning one main cola into two — and if repeated, into four or more. Topping is a high-stress practice in the strict sense because it removes tissue, and the plant responds with a short pause in vertical growth while the new leaders develop. Its advantage is that the change is permanent and structural. It is commonly recommended for growers who want a wide, multi-branch canopy and are willing to accept the short recovery time; the main risk in experienced hands is topping too late or too low and wasting the growth already produced.
LST — bending instead of cutting
Low-stress training (LST) shapes the plant by bending and tying branches down to the sides rather than cutting them, so the plant never loses tissue and does not pause growth the way it does after a topping. The idea is to get the lower branches out horizontally into better light and keep the whole canopy at roughly the same height, so every bud site receives similar illumination. LST is called low-stress precisely because it works with the plant's natural structure. Its limitation is that the main stem keeps growing, so it must be retied periodically, and on very stiff-stemmed plants it can be frustrating without slow, gentle manipulation. Most growers who want an even canopy without cutting pair LST with an occasional topping for structure.
SCROG — the screen-of-green method
The SCROG method (screen of green) runs a horizontal net above the plant, usually 20-30 centimetres above the pot, and weaves the growing branches through and under it as they extend, spreading the canopy flat and level so the light hits every bud site instead of concentrating on one or two tops. It is effectively a systematic, structured way of applying LST — the net does the job of holding each branch in place that you would otherwise have to retie by hand — and it is popular precisely because it produces a dense, even canopy in limited vertical height, which matters most in short tents or cabinets. The usual approach is to fill roughly 70-80% of the screen with canopy before switching to flower, since branches trained after the flip barely move anymore; filling the net is vegetative-stage work.
Defoliation — the leaf strip
Defoliation removes select leaves — usually those shading bud sites or crowding the interior — to improve airflow and light penetration, and it comes with a caveat: leaves are the plant's photosynthetic engines, so stripping too many at once slows it down. As general horticultural practice shows, pruning off excessive leaf or branch tissue can stimulate new growth, but over-pruning stresses the plant. The consistent advice across every technique is restraint: remove what blocks light or airflow, never so much that the plant loses its ability to feed itself.
Choosing a technique and managing the stress
There is no single best technique; the right choice depends on your space, your grow style, and how much stress you want to impose. A height-constrained tent pushes growers toward SCROG or aggressive LST, while a grower with vertical space and no interest in bending may prefer simple topping or nothing at all. The stress cost is cumulative: a plant that is topped, then aggressively defoliated, then heavily bent all in the same week is deeply set back, whereas the same techniques spaced apart let the plant recover fully between them. The practical rule is to train during vegetative growth while the plant can regenerate, apply only one stressful operation at a time, and give healthy, unstressed plants a couple of days to recover before the next step.
How GrowScope helps
GrowScope's plant growth tracking records height and canopy width over time, so you can see exactly how a plant responds to a topping or an LST session — the brief pause after a cut, then the widening of the canopy as the new leaders develop. Logging these measurements alongside training dates lets you judge whether your technique is producing the structure you wanted or whether the canopy is drifting uneven under the light.
Key takeaway
Topping cuts the main shoot for permanent structure, LST bends branches to make a flat canopy, SCROG is LST under a net, and defoliation only removes what blocks light or airflow — do one stressful operation at a time during vegetation.