A cannabis plant grows vertically by nature, but this presents some difficulties, especially in the world of indoor growing where space becomes a limitation. Thankfully, there are plenty of ways we can manipulate a cannabis plant's shape and size to make it grow outwards rather than upwards, allowing our grow spaces to work more efficiently. This article teaches you about Screen Of Green (ScrOG) and explains how to get started using nets to develop an even canopy of big buds.
What Is Screen of Green (ScrOG)?
Simply put, ScrOG is the process of tucking and weaving branches through a screen or net placed above pots to prevent the plant from growing upwards. Tall branches are trained lower, while low branches are allowed to catch up in height before also being weaved into the net. This gradually forms a layer of neatly organised top buds that all get fair exposure to the light above them.
The classic 'Christmas tree' structure of a cannabis plant presents some challenges, particularly when it comes to growing indoors.
Cannabis plants can be trained in many ways, however these methods tend to involve stress, which needs to be carefully controlled to avoid problems. ScrOG is considered a low stress technique (LST) as we do not directly damage the plant.
The intention behind ScrOG is to break the plant's apical dominance, which focuses hormones on the highest part of the plant. When we allow lower branches to reach the same level, we encourage hormones to be evenly distributed across the canopy, creating more top buds.
Pros and Cons of ScrOG
Training cannabis plants is a great way to improve yields and maximise efficiency in your grow room. Not only can you achieve impressive harvests, but you reduce the risk of possible pests because plants develop a hardy structure through the training.
| Pros of ScrOG (Screen Of Green) |
Cons of ScrOG (Screen Of Green) |
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- Higher yields per square meter
- Improved aeration across canopy and around the base of the main stem
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- Requires regular maintenance/reshaping
- Once fully grown into the net, the plants are difficult to access
- Plants cannot be moved around
- Harvesting is harder when buds are intertwined with the netting
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Preparing a ScrOG Grow
Most growers start the ScrOG process during vegetation and continue adjusting branches until week 2-3 of flowering, or when the explosive stretch phase passes. Once flowers start developing it is recommended to not apply further training as this could affect yields. Plants need to focus their energy on bud production.
Space
Growers can have just a single plant in a 1x1m grow space and still fill the whole net with top buds. Normally, between 1 - 4 ScrOG plants are grown in a square meter, otherwise it can get quite crowded.
It is important not to group too many plants together in order to avoid problems with humidity or mold. If you decide to grow multiple plants using ScrOG, space them out so that each plant has enough exposure to light as well as air. With the right training your plants should have filled the space by full bloom.
Pots
Depending on how many plants you want to train, your pots need to be the right size. You may want to manipulate various plants in smaller pots or it might be that you only want to deal with a single strain in a large container.
- 1 plant: 25l pot
- 2 plants: 18 -21l pots
- 4 plants: 11 - 15l pots
Strain
The good thing about ScrOG is that you can grow different strains without worrying too much about one plant towering over the others and stealing most of the light. However, it helps to choose strains that grow more or less to the same height. You'll have less to manage during the vegetative phase as the plants grow more consistently with each other.
Make sure you choose strains that are well suited to training, have short flowering times, and have high resistance to mold and pests:
Sativa - Slightly easier to manipulate in a ScrOG setup due to their tall, lanky branching. A single Sativa can be trained into a 1x1 metre space without too much hassle.
Indica - Benefits from slightly longer in vegetation to achieve a structure that can fill a ScrOG net. May need extra training to widen canopy in preparation for flowering.
Autoflowers - Autoflowering cannabis plants can also be trained into a ScrOG net but you may want to place it lower and be less rigorous with the application of stress.
Screen
There are some important factors to consider when it comes to setting up a screen but overall the process is simple. The first thing is to make sure that the squares in the screen are not too small. Each section should be roughly 5-6in squared to give branches enough space to be weaved without overbending.
Your space will determine how big the screen needs to be. As we previously mentioned, between 1 and 4 plants is ideal for a space of 1x1m. So, decide how many plants you want to grow with ScrOG before proceeding to make a screen. It is better to have a screen that is too big than one that is too small. If you're working in a very small space, you may want to cover the whole area.
Whether you build a standing frame for your ScrOG is up to you. Some growers attach their screen directly to the corners of their grow tent, which avoids the need for building standing legs to support the frame. Make sure you securely fix the frame so you don't risk it collapsing during the grow.
You can use piping or timber to build a frame to the required size. Legs can also be fitted to the frame if you don't plan to use the tent to hold it up. Drill holes or use nails along the frame to fix string or wire (chicken wire works well) in 6x6in squares.
How To Grow Using ScrOG
Normally, ScrOG is used with other stress training techniques to achieve maximum efficiency, but it is not entirely necessary. Topping your plants before they reach the screen can help to fill out the canopy even further and leaves you with more top buds.
- Topping - Once your cannabis plant has 4-5 nodes along the main stem, it can be topped. This splits the main cola into two shoots which can be positioned in opposite directions later on to cover a wider area. If you want more tops, make sure you give the plant time to recover before topping again.
- Setting up the Screen - The screen can be set up once your plants are well into their vegging cycle and once you have applied any training. Remember, your plants will be much harder to access and maintain once the screen is up. It is recommended the screen is placed between 8-12in from the top of the pot/container.
- Tucking/Weaving - As your plants start to grow through the net/screen (about 2.5in above the screen), you need to guide the branches over and under the spaces in between to hold them in place. By the end, you want each branch to have its own square in the net. If the branch feels like it's going to break, do not force it. Find another position that allows you to gradually guide it in the right direction.
- Pruning - Lower branches and popcorn buds can be pruned to improve aeration around the base of the stem. Pruning also helps to direct the plant's energy to the top where there is the most light.
Kalashnikova (Greenhouse Seeds) with ScrOG by Bobrenik from GrowDiaries.
Tip: You may want to apply extra low stress training by tying branches down. This means the plant can begin developing a strong base before it reaches the net.
Have you tried growing using ScrOG? Share you tips with fellow growers down in the comments section!
External References
Evaluation of the Effect of Topping on Cannabidiol (CBD) Content in Two Industrial Hemp (Cannabis sativa L.) Cultivars. Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Horticulture. - Folina, Antigolena & Kakabouki, Ioanna & Tourkochoriti, Evangelia & Roussis, Ioannis & Pateroulakis, Harry & Bilalis, D.. (2020)
The Cannabis Grow Bible: The Definitive Guide to Growing Marijuana for Recreational and Medical Use. - Greg Green. (2003)
Pot Size Matters. - Poorter, Hendrik. (2012)
Apical dominance. Current Biology. - Barbier, Francois & Dun, Elizabeth & Beveridge, Christine. (2017)
This article was updated October 2020.
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