How to scrog marijuana plants
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 “ scr een o f g reen.” 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.
Screen of Green (SCROG) – more bang for your bud!
Even where cannabis is legal, in many places you are only allowed to have a limited number of plants. Those who want to maximise their yield in the face of this restriction would do best with a Screen of Green. A simple piece of netting will stimulate sideways growth and bud formation. The result: plenty of fat, highly potent buds.
Screen of Green (SCROG) is the name of one of the most efficient and productive methods of growing cannabis. It is suitable for both small home growers and professional cultivators. Basically it is a question of making maximum use of the growing area to obtain the greatest possible yield.
A mesh ensures that the cannabis plants can grow sideways in a controlled manner and with even lighting. This leads to the formation of plenty of buds. In the ideal case you will end up with a thick, even carpet of buds.
This article explains how this approach works in detail, and what you need to bear in mind.
1. The right type of plants
Before starting with the construction itself, you need to select the right types of plant. Because the growth phase lasts longer using the Screen of Green method than with other methods of cultivation, auto-flowering cannabis plants are not suitable.
Whether you start from seeds or seedlings is a matter of personal preference. Many growers prefer seedlings because they grow homogenously and their growth structure is predictable, but seeds also work perfectly well with a Screen of Green. You need to ensure that the plants grow evenly and will flower at about the same time.
Ideally, you should use either Indica, or Sativa varieties. A combination is not recommended. If you decide to go with a Sativa variety, then the pruning will involve more work, but the SCROG method is perfect for managing a cannabis variety that typically tries to shoot up.
The following varieties are particularly suitable for a Screen of Green: Michka, Silver Haze, Skunk #1, Super Skunk and Afghani #1.
2. Ideal growing conditions
It is important that the plants have enough space. In contrast to the Sea of Green approach, the pots should not be too close together. Around 30 x 30 cm per plant, or 1 to 5 plants per square metre, has proved successful. Getting a big harvest from just a few plants is one of the main benefits of the SCROG approach!
After planting in the pots, a mesh is installed between the plants and the lights. The plants will grow up to this height. Some growers construct their own netting from (hemp) ropes, washing lines, bamboo or fine wire. It is simpler to work with ready-made manufactured mesh. This comes in various shapes and sizes and is usually made of plastic, metal or nylon.
The height of the netting will be higher or lower, depending on the variety of cannabis being grown. Around 20 cm above the top of the pot is the right height for Indica varieties, for Sativa the best height is around 45 cm, and for Haze or Thai varieties the height should be as much as 60 cm above the top of the pot.
After each harvest, the net needs to be thoroughly washed or replaced.
3. The growth phase
With the SCROG approach, the focus is on the plants growing sideways. Depending on the variety of marijuana, the growth phase lasts three to eight weeks. Fast-growing Sativa varieties will reach the net sooner than Indica varieties.
Once the plants are about 25 cm high, you need to take action. The tips of the main growing points need to be pinched out. This is how you force the plants to spread sideways.
All the shoots that appear above the net need to be fixed into the mesh structure. In most cases you can simply weave them into place. Push the shoots carefully under the next hole to create a thick, even plant carpet.
It is important to avoid breaking off any side-shoots or branches, because the plant will then waste energy sending up new shoots. Very thick shoots that stretch a long way may need to be tied to the netting. The best way is to use plant ties.
The lower branches are pruned to ensure that the plants put all their energy into the upper branches, where the buds will later appear.
4. The flowering phase
Once you are happy with the horizontal growth, you can trigger the flowering phase. This is done by reducing the lighting from 18 hours to 12 hours. Growers have to decide for themselves exactly when this should take place. Generally speaking, with a Screen of Green the vegetation growth should not be pushed to the maximum, as the plant will exhaust itself producing new branches instead of forming buds.
The plant is now allowed to grow up through the netting. In order for the buds to receive the maximum amount of light, as many leaves as possible should be pushed back below the netting. If there is strong leaf growth, it is worth cutting off half the leaves. The remaining half will still provide enough energy for the plants and will keep out less light.
From approximately the second week of flowering, the buds will start to grow vertically. A thick carpet of buds will gradually develop. As the canopy becomes increasingly dense, the lower parts of the plants receive less and less light. The leaves will begin to turn yellow. At this time, it is better to cut away all the leaves, branches and buds that are below the netting.
This will ensure that the plants put all their energy into the top buds, and it also improves air circulation. This is important, as large buds in particular have a tendency to attract mould.
As with as any other intervention on growing plants, such as fertilising, great care is needed when pruning or cutting away plant material. It is better to proceed gradually. Do not remove all the branches and leaves at one time, as this may cause the plants to go into shock and stop growing normally or become sickly.
Once you master the SCROG approach, you will be rewarded with a rich harvest. Screen of Green yields can be as much as 20% higher than other forms of cultivation. Of course, some practice is necessary; there is no such thing as an instant expert.
Best “How to ScrOG” Guides
A great deal of confusion exists regarding the difference between Sea of Green (SOG) vs Screen of Green (ScrOG) methods of growing cannabis. Before I present what I consider to be some of the better “How to ScrOG” Guides, allow me to briefly define the difference between SOG and ScrOG.
SOG – SOG is used to create “perpetual harvests”. The method involves high plant counts per cu ft and short grow cycles. Clones are introduced to 12/12 flowering with little to no veg cycle. Trellis or other screen material may be used to support heavy colas but no plant training techniques are used. Many growers cannot use SOG due to local plant count limitations.
Sea of Green (SOG), multiple plants
ScrOG – The ScrOG method involves lower plant counts, typically 1 plant per 2’x2′ area. Veg periods vary, with longer veg periods resulting in canopies larger than 2’x2′. Screens are used to facilitate plant training which results in short bushy plants with virtually all target bud sites in the best lighting zone. ScrOG method is touted to produce 2 to 3 times the yield of traditional growing methods.
Screen of Green (ScrOG), single plant
There are a number of variations of the ScrOG method. We have scoured the internet and selected what we consider to be some of the better “How to Guides” below.