How to


The Screen of Green Training Method

Growers searching for the extra edge that would put their crop in the best position to produce bigger, better buds should consider training their plants. Both the commercial cultivator and hobby-grower can benefit from plant training. After all, who would say no to larger, higher quality yields?

Plants respond extremely well to any training that increases light exposure, multiplies bud sites, and promotes plant health. A popular, involved, and rewarding training technique is known as the Screen of Green (SCRoG), or “scrogging”.

The SCRoG method happens in three main stages:

1 . The cultivator installs a screen frame featuring a grid or trellis above cannabis plants in the vegetative stage.

2 . The cultivator strategically tops their plants, training the new growth to grow laterally along the screen’s underside.

3 . Lastly, the cultivator tucks any new growth under the screen’s openings, allowing the plant to fill the total area of the frame evenly.

Cannabis plants cultivated via scrogging develop a low, horizontal profile of bud sites that are evenly distributed across the plane of the screen. Wondering how and why this technique works? This tutorial is for you. Read on!

Please keep in mind the Screen of Green method differs from the Sea of Green technique. The Sea of Green (or SOG) emphasises the growth of an apically dominant main cola that towers above the rest of the bud sites with minimal plant training. This technique works best with a larger number of plants in grows with more space. Conversely, using a SCRoG screen is a low-stress training method that can optimise a small space for the home grower.

High yield, healthy plants in limited space

This departure from the natural, vertical “Christmas tree” growth habit of cannabis plants creates several advantages.

Growers increase the plant’s overall light exposure by encouraging a low, even canopy across the plane of the screen. The less-developed bud sites that would have been shaded in an apically dominant plant receive more light and develop into full-fledged flowers rather than small “popcorn” buds that usually form underneath the canopy, leading to high yields and higher quality buds.

Other positive outcomes of the scrog grow are higher THC content, more robust terpene profiles and denser trichomes, as increasing light exposure will stimulate a plant’s photochemical production! Happier plants, happy growers.

In addition to maximising a plant’s photosynthetic potential, scrogging promotes plant health by increasing aeration above and below the canopy. The grower reduces the risk of mould, pests and pathogens by limiting the plant’s vertical height and creating more space for uninterrupted airflow. The grower can supplement this by pruning any superfluous plant material to reduce overall humidity, vectors for disease and redirect energy towards flowering.

The SCRoG technique is ideal for cultivators who have limited vertical space. The horizontal growth habit encouraged by SCRoG takes advantage of space that a vertically dominant plant’s lower branches wouldn’t grow into due to limited light exposure. The taller main colas at the top of the plant tend to shade it’s lower lateral branches.

Also, the need for more grow room space isn’t as pronounced as the screen allows the plant to grow as wide as the available floor space. Lower down, the canopy is also less likely to overheat and burn from heat exposure from grow lights. Cultivators growing in tents without robust cooling capacity will find this attractive.

SCRoG is practical for discreet cultivators growing a smaller number of plants (or even a single plant) as the yield per plant increases.

SCRoG is a rewarding (if somewhat challenging) technique for any grower to develop. Cultivators can develop a better eye for their plants’ health and characteristics by spending time training their plants. This leads to a multitude of positive outcomes, from timely identification of pests, viruses, and diseases to identifying desired traits in a crop.

Growers implementing SCRoG will consider building and installing their SCRoG net, topping their plants, and situating new growth correctly as the main objectives.

Scrogging can be done with either sativas or indicas – the stretchy, long growth habit of the former may see more success using this method. As with most cannabis cultivation techniques, the best way to learn is via practical application.

Building and installing the screen

The screen is stretched across a square or rectangular frame of wood, PVC plastic, or any sturdy material. Weight is the main factor here, as heavy frames may damage plants if not appropriately secured, knocked over, or bumped into. The frame’s dimensions depend on the grow room space available; ideally, the frame is slightly smaller than the grow space, and a larger screen is preferable to one that is undersized.

Eye hooks, screws or nails fixed at regular intervals (5-6 cm) along each of the frame’s four sides will serve as anchors for the screen. Consider using string, hemp twine or plastic trellis material for the net, stretching it across the frame and securing it to the anchors. Alternatively, fix the net to the frame using staples.

Avoid chicken wire as screen material; not only is it a puncture hazard for the cultivator’s fingers, buds will grow into it, which will make the harvest process more difficult as the buds will need to be cut from the wire. If using biodegradable hemp cord or jute twine, fibres may fray and find themselves inside the bud structure. Plastic trellis netting is an attractive choice for the mesh but may not prove as easily removable as string.

The screen can be positioned anywhere from 18-60 cm above the plant’s growing medium, depending on the cultivator’s needs and the variety of cannabis being grown. The cultivator can adjust the screen’s height using horizontal shower curtain rods or vertical legs that can be raised using woodblocks (if growing in a tent with flexible walls), depending on the growth of their crop. Keep in mind that plants growing into higher screens will require more pruning underneath the screen.

Cannabis plants grown using SCROG growing technique

Topping and tucking plants to create your SCRoG

Topping cannabis plants will put them in the best position for the SCRoG method. The grower can facilitate the lateral growth of the plant early in veg by removing the newest growth above the 3rd to 5th node of a plant or branch, creating more stems to train under their net. Any energy that would have been used to encourage the growth of the main stem will instead divert to the two new shoots that will develop 2-3 days after topping.

When new shoots are 5-6cm above the net screen, carefully tuck them under the screen and guide them to the adjacent square. The cultivator can prevent overcrowding by adhering to one shoot per square. This results in a low, even carpet of buds benefiting from the full light exposure provided by the screen’s structure.

The grower’s aim is to fill the net grid as much as possible with this mild method of LST just before or just after inducing flowering. Tucking and weaving new shoots into squares can continue into the third or fourth week of flowering time.

When most of the screen is filled, remove any growth beneath it. These branches and bud sites will be shaded by the even canopy above, wasting energy that could be put towards the plant’s flowering stage and improving air circulation. Combined with the “stretch” that occurs as plants begin to flower, this redirected energy improves the quality and overall health of a cultivator’s crop and increases photochemical capacity, raising cannabinoid concentration, terpene production, bud size and quality.

Post author
Martin is a production horticulturist with experience in commercial cannabis cultivation and sustainable farming from his time with Emerald Cup Award-winning farmers Esensia Gardens in northern California's Emerald Triangle.
See more from Martin

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