An Introduction to SCROG (Screen of Green) - Happy Hydro

SCROG, also known as "Screen of green," is a riff on a cannabis cultivation technique called SOG or Sea of Green. Primarily designed for use in indoor cultivation, SCROGing combines topping with low-stress-training (LST) for improved yields.

Although often considered an advanced plant-training method, it is quite manageable even for relatively new growers. Provided you have a few grows under your belt, the right set up, and the steps nailed down, you should see immediate returns on investment. 

What you will need is an understanding of the cannabis growth cycle. It is instrumental to work with the strain before manipulating it with SCROG. This nails down the details of the vegetative cycle and timing.

On almost every forum thread detailing the SCROG technique, an expert grower will highlight just how important it is to know the strain first, and SCROG second. Remember, even for advanced growers, SCROG is a technique that takes a little trial and error to perfect.

What is SCROG?

This technique gets its name from the screen (or netting) placed over the canopy, which separates the individual colas and provides some structural support. Some grow tents even come with a netting as a complete indoor cultivation package.

The term SCROG is a bit misleading because it's not a standalone technique but a combination of several other methods: topping and LST. A net over the canopy, combined with these pruning and training methods, increases yields, but only to a point.

Each time a section is topped, it will produce more colas, but smaller than the original. With enough rounds of topping, the total yield versus flower size doesn't pan out. Most growers will restrict the number of times they top the plants, to guarantee a decent-sized flower.

The first technique in SCROG is topping. Topping cuts off the upper set of leaves from the main stem (or secondary branch), to promote side growth. It is quite literally, cutting the top off a plant. Cannabis will naturally grow two branches in response to the topping. If you top the main stem, it becomes two. If you top these two, it will grow into four, and so on.  

After topping, the second technique required for SCROGing is LST. This trains the plant to grow in unnatural ways to promote higher yields. In SCROG, growers force the new secondary stems created through topping are outwards under the screen, at a horizontal angle from the main stem. Each cola along the branch will eventually redirect vertically in between individual sections of the screen to point towards the lights.

Step by Step: How to SCROG

Prune and Train in Vegetation Stage

  1. Create a SCROG feature within your grow room. Aim to place the screen roughly one to two feet above the split in the main stem (depending on the strain, set up, etc.). This netting should be adjustable somehow. Trellis netting is a cheap, easy to set up SCROG option, but simple string also works in a pinch. 
  2. Starting with a seedling. Pinch off the main stem once it has five sets of leaves. Pinching off the fifth set, just above the fourth node, will promote a division into two main branches. Once the plant has recovered, it will grow four branches (two primary, two secondary). 
  3. Begin LST. Gently fold down each branch to lay against the soil and hold in place with a "U" shaped garden stake. After a few days, the plant naturally diverts its leaves and baby colas towards the light source. As it grows in this position, it will expand into this newly available canopy area.
  4. Top the main branches again. Remember, each time you top a branch, it will produce more (but smaller) buds.
  5. Recovery. Continue in vegetation stage to allow the plant recovery time. Continue to LST all the new branches.
  6. Continue until you've reached the desired number of colas.

SCROG in Flowering Stage

  1. Introduce the screen. A few weeks into the flowering stage, it's time to place the screen over the canopy. 
  2. Initial positioning. With the plant placed underneath the screen, gently work the branches horizontally underneath the screen in the desired direction. Move side branches away from each main branch and allow them to grow in the new space. As they reach two to three inches, tuck them into the netting. 
  3. Tuck colas into netting. For the first three weeks of flower, continue to tuck individual colas up between each space of the netting. Branches with colas will continue to grow above the screen, but each separated by the netting.
  4. Secure in place. Use plant ties or zip ties to manipulate the plant as needed.
  5. Continue into flower stage. After three weeks, stop training to promote maximum flower development.
  6. Harvest. Assess daily, using a trichome microscope, to determine peak potency and harvest when the time is ripe.

Practice Makes Perfect with SCROG 

Before launching into SCROG, work with a single strain to understand its characteristics. It may also be helpful to practice the individual techniques and understand the nuances of your chosen strain beforehand.

SCROGing is more work than the standard cultivation techniques, but well worth the payoff at harvest time. With the screen of green, yield per plant can double, triple, or even quadruple. 

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