Scrogging and Trellising: How to Train Cannabis for an Even Canopy (2026)

By James Buddsey · Updated October 30, 2026

Scrogging (Screen of Green) is a training method in which a horizontal net or screen holds a plant’s branches in an even, flat canopy, while trellising is the broader practice of supporting stems and heavy flowers with netting, stakes or ties. Both aim to put more bud sites at the same distance from the light and to keep heavy colas from toppling. They work best when combined with early topping or bending, and they are less suited to autoflowering plants and some tall sativa-type cultivars.

Cannabis naturally grows one tall main stem with a dominant top bud, a trait plant scientists call apical dominance. A 2025 paper in the Journal of Cannabis Research reviewed how growers use training to break that pattern, and it is the main source for this guide. Its authors point out that much of the practical knowledge here comes from grower communities and blogs rather than controlled trials, so treat specific numbers as common practice, not settled science (Ijoma et al., J Cannabis Research, 2025).

Scrogging vs Trellising at a Glance

Why a Flat Canopy Helps

Light is the reason most growers train plants. Plants intercept light from the top down, and a large 2019 meta-analysis noted that in indoor lighting systems the top of the canopy is often light saturated while the canopy as a whole is light limited (Backer et al., Frontiers in Plant Science, 2019). A flat, even canopy narrows that gap, because more flowers sit in the strong light and fewer sit in shade.

The 2025 review lists related benefits of an even canopy: more uniform light absorption, better air circulation, and easier support for large plants. It adds that a uniform canopy is easier to manage for pests and disease because colas sit at similar distances from one another (Ijoma et al., 2025). Airflow matters for another reason: high humidity delayed flowering and lowered cannabinoid concentrations in a 2025 experiment, and a thick canopy traps moisture (Corredor-Perilla et al., Frontiers in Plant Science, 2025).

How Scrogging Works, Step by Step

Scrogging is usually one part of a larger plan. The 2025 review describes a sequence called mainlining that combines low-stress training, which includes screen-of-green, with topping and pruning. Here is the order it describes, with the paper’s cautions attached:

1. Start with a healthy young plant. The review says most growers wait until a seedling has about five or six nodes, roughly 25 centimeters, which it says should occur within about two weeks of the start of vegetative growth. Plants grown from seed tolerate training better than clones (Ijoma et al., 2025).
2. Top the plant. Cutting off the growing tip breaks apical dominance. Two new main shoots form, each capable of becoming a full-size cola (Ijoma et al., 2025).
3. Bend and tie the shoots. Low-stress training means gently bending stems and securing them in place, often with ties, so more bud sites receive light and the plant grows outward. The review describes tying the two main shoots down about 90 degrees after roughly five days of recovery.
4. Repeat in measured steps. Each topping doubles the number of main shoots: one top gives two colas, two tops four, three tops eight. The review says three to four toppings is typical, five can produce 32 colas, and more than six may stress the plant in ways that are hard to fix (Ijoma et al., 2025).
5. Weave the screen. The screen goes above the plants and branches are tucked under it as they rise. Stop topping and training once the plant enters flowering (Ijoma et al., 2025).

Trellising: Support Before the Weight Arrives

Flowers get heavy. The review notes that colas full of resin, or seed, can become too heavy to stand erect and bend under their own weight, and that this is when a screen is added to provide support (Ijoma et al., 2025). The practical rule is to put the net in before you need it, because lifting a snapped branch is harder than guiding a young one. Strong plants with many colas, including tall cultivars such as Blue Dream, which our strain guide says stretches in flower and benefits from topping and a screen or trellis, are the usual candidates.

Risks and Limits

The review lists disadvantages that apply to scrogging as part of mainlining, and it is worth reading them before you start (Ijoma et al., 2025):

• It takes experience and labor to set up.
• Done late, the plant may lack the resources to recover.
• Mistakes can cause permanent damage and lower yield.
• Cuts are entry points for infection. The authors urge washing hands with soap and alcohol and sterilizing scissors or razor blades with alcohol or a flame.
• Training keeps the plant in a vegetative state longer, delaying flowering by about two weeks in the review’s summary.
• It suits some strains and not others. The authors say it is not suitable for some tall sativa-type strains or for autoflowering strains.

The review also says clones may be less suited to hard training than seed-grown plants, because they can lack apical dominance and produce uneven structure (Ijoma et al., 2025).

What About Plant Count and Yield?

Training adds bud sites per plant, which is attractive when plant counts are limited. That matters in places such as Oregon, where adults may grow up to 4 plants per household. A 2019 meta-analysis found that higher plant density lowered yield per watt of lighting and THC per square meter, though density was tangled up with other factors, so the authors did not claim it as a simple cause (Backer et al., 2019). No controlled trial we found compares screen-of-green with other methods head to head, so be skeptical of any specific yield multiplier.

Where This Fits in Your Grow

Training belongs between germination and flowering. See basic marijuana growing for the full sequence, the cannabis plant life cycle for stage timing, and trimming cannabis plants for pruning and defoliation. If you are choosing what to grow, our guide to the top strains to grow indoors notes which cultivars stretch.

Scrogging and Trellising FAQ

For adults 21+ in legal states. General information, not medical advice.