Trellising is a cultivation technique that uses a structural support system to manage the growth of cannabis plants. This practice is employed primarily to support the plant’s structure, as the heavy weight of developing flowers can cause branches to bend or snap. Trellising also optimizes the available canopy space by spreading out the branches, which allows for better light penetration and air circulation throughout the foliage. Guiding the plant’s growth horizontally ensures that more potential bud sites receive sufficient light energy, which is fundamental to achieving maximum yields. This structural manipulation counters the cannabis plant’s natural tendency toward apical dominance by creating a flat, even plane of growth.
Required Materials and Optimal Timing
Setting up a trellising system requires specific components for stability and plant safety. Frame materials include PVC piping, bamboo stakes, or metal tubing, secured with fasteners like zip ties or plant tape. The netting is typically made from nylon or polypropylene; select food-grade or non-toxic materials to prevent contamination. Netting hole sizes commonly range from 3.5 inches to 6.5 inches, with larger sizes offering more room for weaving and thicker colas.
The timing of installation is a significant factor in trellising success. The support structure should be put in place during the plant’s vegetative phase, before the rapid growth associated with flowering. Ideally, the first net is installed when the plant reaches 50 to 70 percent of its desired final height. Placing the net at this stage allows the cultivator to begin guiding the branches horizontally early, maximizing the time available to fill the screen before the plant enters its “stretch” phase in early flower.
Horizontal Netting Techniques
The Screen of Green (SCROG) is the most common technique utilizing horizontal netting. This method involves training the plant to grow through a single or double layer of mesh to create a flat, uniform canopy. The goal of SCROG is to ensure that all potential bud sites are positioned at the same height, keeping them equidistant from the light source for optimal light absorption. By forcing the plant to spread out horizontally, the technique maximizes the yield per plant, unlike the alternative Sea of Green (SOG) method which focuses on yield per square foot.
SCROG fundamentally alters the plant’s growth structure, unlike simple staking, which provides localized support for individual heavy branches later in the flower cycle. The SCROG technique is a low-stress training method that uses the net to strategically manipulate the plant’s entire profile throughout the vegetative and early flowering stages. This systematic horizontal training creates a dense, even layer of flowering tops, which improves light distribution.
Installing the Support Structure
Installation begins by measuring and preparing the frame components to fit securely within the designated grow space. Materials like PVC or bamboo should be cut to the exact dimensions of the area to create a rectangular perimeter for the netting. Next, the frame is secured to the support structures of the grow environment, such as vertical poles, using sturdy zip ties or clamps. This attachment must be firm to withstand the eventual weight of the heavy, mature colas.
Once the frame is secure, the netting must be attached and stretched tautly across the entire area. A tight net is essential because slack will allow branches to sag, compromising the even canopy. The optimal height for the first net is typically between 8 and 12 inches above the growing medium or container. This height provides enough room for the cultivator to access the plant bases for watering and maintenance while still being low enough to begin the horizontal training process effectively.
Training the Canopy After Installation
After the net is installed, the ongoing process of training the canopy begins by manually manipulating the growing branches. The primary technique is “tucking” or “weaving,” where the plant’s growing tips are gently bent and pushed underneath the nearest net square. This action forces the branch to grow horizontally beneath the net until the tip emerges in the next square, encouraging lateral development and filling out the screen. The tucking process is repeated daily during the final weeks of the vegetative phase and the initial stretch of the flowering phase until the net is almost entirely filled.
Another important post-installation action is managing the lower canopy through a technique called lollipopping. Lollipopping involves selectively removing the lower third of the plant’s growth, including small, unproductive branches and leaves that receive little light. This pruning redirects the plant’s metabolic energy away from shaded, low-yield areas and focuses it entirely on the developing flowers above the trellising net.
If the plant’s flowers become excessively heavy during the later stages of bloom, a second layer of netting can be added. This second layer should be placed 8 to 12 inches above the first net to provide additional vertical support for the mature colas.