The SCROG cannabis growing system

WHAT IS THE SCROG TECHNIQUE?

“ScrOG” has become a term used for the “Screen of Green” cannabis training technique.

The purpose behind Scrogging is to manually change the plant’s natural growth patterns by putting all the buds on an even layer. This is accomplished by bringing the low stuff up (by getting screen good and low) and bringing the main cola down (by stopping it via topping) to the canopy.

The rough pics below illustrate my point.

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.

SCROG growing

Growing marijuana with the SCROG method

To use this method we only need from 1 to 5 cannabis plants for each m2 of crop. At the end of the flowering stage, the result will be the same regardless the number of plants, since we’ll get exactly the same yields using one, three or five plants. The only thing that may vary is the time needed to harvest our plants.

To make a SCROG setup we place a screen or mesh (preferably made of 6/8mm diam. bamboo sticks) with 5-10cm holes approximately 20cm above the pots. As plants grow, we train their branches using the mesh to control their height, always leaving the tops at the same height than the mesh. This way, the apical growth of the plant decreases in favour of horizontal growth, developing more branched plants.

This process should be carried on until 70% of the available space is covered, what will highly depend on the chosen strain. Now we only have to change the growing photoperiod (18/6) to flowering (12/12). During the first days, our plants will continue growing and stretching, what allows the plant to fully occupy the growing space. During the entire blooming phase all our flowers will be at the same distance from the lamp, what produces first quality harvests of first quality buds, homogeneous and almost identical.

SCROG growing

Flowering should be performed as usual, without any special care, doing exactly the same that we’d do in any other type of cultivation.

This method is highly recommended when flowering sativa marijuana strains that tend to grow too much and have a notable stretching during the pre-flowering stage, being difficult to control in small growing tents, but that can cover all the growing space (mesh) very quickly. It is also advisable when growing in small spaces. Any strain is suitable for this technique, just bear in mind that if you are flowering Sativas you only need to have 50-60% of the growing space covered before changing the photoperiod, while if you are flowering Indicas 80% of the space should be occupied by the plant before flowering starts.

If we want to use this method with a single plant, we must use at least a 25L container and grow our plant for 5-7 weeks before flowering it, so it occupies 70% of the available growing space.  Once the mesh is covered, change the photoperiod to flowering and the plant will cover the rest of the space during its stretching or pre-flowering growth.

On the other hand, if we are using 3-5 plants per m2, we need 12L containers and give our plants about 3-5 weeks of growth before flowering them.

One of the main advantages of this technique, besides the forementioned saving in cuttings or seeds, is the easy maintenance of the system; once the plants stems have been properly trained through the holes we just have to water very few plants per m2, which is a lot easier than watering 20-30 plants, as is the case in other high-yielding systems like the SOG – Sea of Green – that we will discuss in another post further on.

ADVANTAGES OF GROWING CANNABIS IN A SCROG

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 maximise 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.
  • Maximise 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 maximise their output with this method. Cultivators can even train several plants and merge them into a single ScrOG.

WHEN TO 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.

WHEN NOT TO SCROG

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.

SCROG growing

HOW TO SCROG: MAJOR CONSIDERATIONS

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.

SELECT THE RIGHT STRAINS

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 utilise more plants to maximise 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 minimise the work you have to do.

Mounting

Many build feet for their screens. This somewhat limits you.

I like having screens where the height can be adjusted either by a peg system or some other ingenious way.

I use shower curtain rods for mine and they work well, but you have to get used to not leaning on the screen or disaster can be right around the corner. To me, it’s worth it not to have legs in the way. It allows more room for “under canopy” cleaning and maintenance.

How secure are these shower rods?

You have to get used to not putting pressure on them but they were handy because of all the extra room for cleaning by not having the 4 legs on the screen. I don’t have any problem with the plants lifting up the screen.

I have a set height now, 4″ above the bucket lid, so I just built in stops to rest it on, works great.

The shower rods were great too though…cheap, effective and adjustable. Like I said though, the key is to get that screen real low and I think at 4″, I’ve maxed that.

Do you have to build the screen to the exact length of the closet? 

Yes, but it’s not THAT exact. It has about 5 inches of play side to side.

This is a quick vid I made to show folks how to maximize a small space, back when I was still learning to scrog (not that you ever stop learning…). It shows how the curtain rods are used.

Vegetative Stage

So now that we are all laced up and ready to go, let’s talk about a key element to Scrogging: Veg time.

When Your Plants Don’t Have to Move

Scrogging is easier when your plants stay in one spot throughout their entire life, from vegetative stage to flowering, but depending on your setup, you might have to move them.

In this situation, you can just set the screen (more below) after you’ve done all of your topping and let the plants grow into it. You’ll have to touch up the screen a few times over the coming weeks to make sure branches are spaced out evenly and not too crowded.

When Plants Have to Move Into a Flowering Space

Make sure your plants are in their final place because you won’t be able to move them once under the screen. Plants also need to be transplanted to the appropriate size of pot.

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