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How to scrog marijuana plants

What is scrogging?

A scrog over an outdoor cannabis crop. (SEASTOCK/iStock)

Scrogging and trellising are two processes that spread out and set cannabis plant branches using string, rope, or netting. They may look similar, but there is a subtle difference:

  • Scrogging helps train plants to get higher yields
  • Trellising simply supports plants

“Scrog” is short for “screen of green.” Yet another term for scrogging is “sea of green.”

Why scrog marijuana plants?

Scrogging stretches marijuana plant branches out into a screen, creating an even canopy. Scrogging has several benefits:

  • Light can hit more branches, therefore producing more buds and higher yields
  • Air can flow through the plant more, helping to reduce mold and pests
  • Branches get structural support, so heavy buds don’t weigh down the plant and snap branches
  • It makes plants easier to work on because branches are more spread out

All branches above the screen—the canopy—will fill out with thick buds, while most of the foliage below the screen will get shaded out. You’ll want to prune the bottom branches and dead leaves below the screen because they either won’t produce buds or will produce buds that are of poor quality. 

By cutting off these lower branches, the plant can focus its energies above the canopy, producing high quality buds up there. 

When to start scrogging marijuana plants

Scrogging works best if you stay one step ahead of the plant—ideally, you want to set the screen so branches grow into it, as opposed to having to push branches into it after. Monitor your plants week by week and help branches through the screen as they grow. 

If you do need to set a screen after the fact and put branches in it, it’s not the end of the world, just be gentle with your plants.

Marijuana branches should be in a screen after plants are done getting topped, and before flowering. If you still have to top or cut off branches, plants will take a different shape, so they shouldn’t be in a screen yet; and you want branches set in a screen before flowering so as not to disturb plants while they are producing buds.

Other considerations before you scrog weed

Scrogging works best when combined with topping. Topping will help keep branches a similar length and keep the canopy even so light can hit buds sites evenly.

  • Height: Set the screen about 1 ft. above the base of the plants.
  • Size: It’s helpful to keep the same strains together as they will have a similar size and shape. If you have multiple strains, group them by height.
  • Spacing: Be sure to space your plants properly. The branches of one plant should slightly interlock with the branches of the plants next to it—generally speaking, this means about 1-2 ft. between pots. A better way to gauge spacing is to stretch out the longest branch of a plant toward the plant next to it—if it reaches the middle of the next plant it’s too close; it should overlap with the longest branch of the adjacent plant by 6” or so.

Scrogging marijuana outdoors

Outdoors, the easiest way to spread branches out is to buy a tomato cage or some other pre-made structure, and put it around the plant when it is young. The plant will grow into it and as it does, you can help branches along by pulling them through different points of the cage.

Depending on how big your weed plants are or how many you have, it may be easier to build a frame or set posts around all the plants. Outdoors, you can drive T-posts or large wooden stakes into the ground to form a rectangle around your cannabis plants. 

You can then stretch a screen over the posts, slide it down to the level of the plants, and either let them grow into the screen or pull the branches through it.

Scrogging marijuana indoors

You can build a frame or structure around plants when growing indoors too. A common indoor trellising structure is a frame made out of PVC pipe. You can also affix a set of post of some kind to any structure sturdy enough to support a screen—another common setup is to nail some 2x4s upright into a plant tray. 

How to place marijuana branches in a scrog

There’s an art to scrogging—you need to put a set of plants together and stretch out their branches so they don’t grow on top of each other or shade each other out. 

Scrogging involves reading a plant to see what it needs and usually involves some fine-tuning. But with a little time and patience this training technique will keep your marijuana plants healthy and lush, and give you big yields.

An important question to ask before putting branches into the scrog is: Where does the branch want to go? If a branch doesn’t want to stay where you put it, you might need to place it somewhere else. Don’t force it.

The branches in the screen should interlock with the branches of the cannabis plants around it, like hands folded together.

Keep in mind that each branch has a different length, and there’s no exact measurement for how close or far apart each plant or branch should be. 

Try to fill each square mesh of the screen with a single branch—avoid putting two branches in one square and try not to leave a square empty. This will ensure each branch gets enough space and light and that the screen is utilized to its maximum potential. The more light each branch receives, the bigger buds will get. 

Some additional tips:

  • Start at a corner and work your way around the edges, getting the middle of the screen last.
  • As mentioned above, stretch out the longest branch of a plant toward the plant next to it—it should overlap with the longest branch of the adjacent plant by 6” or so.
  • Work methodically, putting all branches of one plant into the screen before moving on to the next plant.
  • Stretch a branch out as far as it can go, pull it up through the screen, and rest it on the screen. If it falls through, pull it back one square closer to the center of the plant.
  • If you’re having trouble with a set of branches, try rotating the entire plant. Repositioning it can open up new possibilities.

Scrogging can stress a cannabis plant out, and you’ll probably notice that the plants look a little wilty afterward. But fear not—with some direct light they’ll bounce back, and putting them through the scrog will be worth it in the long run.

It’s a good idea to water plants within 24 hours of scrogging to give them a little boost to get past the stress of the procedure.

It’s also a good idea to check the scrog 2-3 days later to touch it up. The plants will have grown into the screen a little bit in those couple of days, and you’ll have a better sense of where each branch wants to go and where buds will develop.

Pat Goggins contributed to this article.

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