Growing cannabis with the SCROG (Screen of green) method

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Left to their own devices, cannabis plants grow taller than they do wide. The ScrOG technique aims to bring the lower branches up and the upper branches down, stretching them across an evenly distributed plane. By placing a screen above the growing medium, cultivators can weave branches through the mesh as plants grow and mature. By redirecting individual branches and running them lengthwise across the screen, growers achieve a flat horizontal canopy.

But why ScrOG in the first place? Well, the technique offers plenty of advantages, including:

• Light exposure: A ScrOG canopy receives even light exposure. Untrained cannabis plants feature one main cola that rises above the rest of the plant, meaning the light rig must remain above this point. In contrast, the lighting rig can hang directly above every flower in a ScrOG setup.
• Yield: Because each bud site receives adequate light, they maximize their photosynthetic potential, leading to an increase in size and resin production. This level of training also transforms the main stem and central cola into a multitude of both.
• Aeration: The horizontal screen of green receives adequate airflow above and below the canopy. The addition of a fan will further enhance this benefit, reducing the risk of fungal pathogens.
• Maximize space: Many growers manage to obtain a larger yield from a single scrogged plant in a small space than with numerous smaller, untrained plants. Covert home-growers can maximize their output with this method. Cultivators can even train several plants and merge them into a single ScrOG.

You’ll start to guide your plants through the screen as soon as they start making contact with it. We recommended positioning the screen around 20cm above the base of your plants, so their rate of growth will determine when exactly you start to ScrOG.

Start the “tucking” process as the apex of each plant begins to grow through the screen. Wait for each tip to grow 5cm above the screen. Proceed to tuck each individual shoot under the screen and direct them through the next square away. Tucking will lay the foundation of the ScrOG process, so be mindful of the direction you want each branch to grow towards.

Continue this process throughout the vegetative phase. Switch to a 12/12 light cycle to induce flowering when the screen becomes mostly filled.

Continue to tuck and weave each branch over the next 2–3 weeks as your plants begin to stretch. This increase in growth will allow you to fill out the screen before your plants enter the true flowering stage and slow their growth.

Avoid tucking and weaving your plants too early. It might be tempting to rush ahead, but they’ll only grow well beyond the screen. Training your plants into the mesh too early—during the early vegetative phase—will lead to extra work. You might even run out of room on your grid.

Although ScrOG setups can look complex, the technique requires little work. Even if you have limited experience growing cannabis, you can jump right into the technique and produce good results. Just make sure to follow the guidance below, and you’ll be in for a happy harvest.

With or without training, growers should always tailor strains to their preferences, spatial limitations, and climate. Some genetics are far more compatible with the ScrOG technique than others. Check out the best characteristics for the job below.

• Stretchy sativas: Sativa-dominant cultivars are lanky, tall, and stretchy in nature. Growers can easily weave their branches and fill out a ScrOG. Of course, you can select smaller and bushier indicas too—just utilize more plants to maximize the potential of your space.
• Strain matching: Growers can cultivate several different strains in the same ScrOG setup for a nice variety of flowers. Try to choose strains that reach a similar average height to minimize the work you have to do.

You’ll need to select the correct pot size to optimize your grow. This variable will shift depending on how many plants you want to incorporate into your ScrOG. Consider the following factors:

• Multiple plants: If you want to grow several plants in a smaller space, you need to consider spacing (more on that below). For this reason, each plant will require a smaller pot. An 11l pot will make the most of the space while optimizing plant growth.
• Single plants: You can increase the pot size when using a single plant in your ScrOG setup. A 25l pot will give your plant enough room to establish a substantial root system and large canopy.
• Fabric pots: The ScrOG technique greatly improves aeration of the canopy—using a fabric pot greatly increases aeration of the growing medium. 

Growing multiple plants in a ScrOG means you can harvest several of your favourite strains. You can grow high-THC and high-CBD varieties together, and even match plants based on their terpene profiles.

As one of the most important factors when growing several plants, the correct spacing will help minimise mould formation while encouraging the best yield possible. The goal: Fit in as many plants as possible for best results, while keeping them far enough apart to increase light exposure and aeration.

You’ll get away with squeezing four small/medium-sized plants per m² in a maximum pot size of 11l.

Building a ScrOG screen is easy peasy. If you’ve ever constructed flat-pack furniture or hung a picture on the wall, you’re more than qualified. Make sure you have the following resources and equipment, and you’re good to go.

• Size: This depends on how many plants you want to grow, and their size. Your canopy needs to be completely even, so an oversized screen will cause fewer problems than an undersized one. If you're not sure of the dimensions, overshoot a little. If you’re really limited in space, build a screen as big as your area can handle.
• Screen: String or hemp cord does the job perfectly. Cannabis branches almost stick to the coarse texture of string, and you can easily dispose of the material afterwards.
• Frame: Make a square (or rectangular) frame using four pieces of timber which are slightly smaller than your growing space. Cut four evenly sized legs and attach them with screws from the top of the frame. You can also create the same design using PVC piping. Screw eye hooks into the top of the frame with 6cm in between. Attach the string.

After a couple of weeks in the seedling stage, your plants will enter the vegetative phase. You’ll need to tick the following tasks off your checklist to ensure your plants are fully compatible with the ScrOG method.

• Topping: After each plant has developed 5 nodes (the point at which a branch meets the stem) you’ll need to top your plants at the highest node. Clean a pair of sharp scissors and snip the main stem just above the intersection. Topping forces plants to divert their growth into several main stems as opposed to one. This encourages lateral growth more suitable to the ScrOG method.
• Setup: Position the screen approximately 20–40cm (depending on the type of plant you are growing) above the top of the growing medium. Position your lights in a way that offers even light exposure over the screen.
• Weaving: Unlike runner beans and hops, cannabis branches don’t act like vines. You’ll need to manually weave them through the screen. Aim to fill each square with an individual branch to avoid overcrowding. Be gentle yet effective. If you feel a branch doesn’t want to go in a certain direction, don’t risk breaking it. Direct branches in different directions to fill out the screen and prevent overshadowing and crowding.

Keep weaving throughout the early flowering phase until your screen becomes filled. Secure branches in place using soft garden ties.

• Pruning: Remove the branches from below the point where you topped your plant. This will force your plant to direct all of its available energy to the canopy. These limbs require their own supply of nutrients and water. Remove them from the plant to free up resources.
• Maintenance: Cannabis plants often feel stressed throughout the ScrOG process. Make sure to water them immediately after every weaving session. Going forward, only water the soil when the top 3–4cm is completely dry. Keep your plants well-fed with optimal nutrients to avoid deficiencies.