The SCROG cannabis growing system

The SCROG training technique is a growing system that allows us to get the best yields from our grow tent with very few plants.

SCROG are the initials of Screen of Green, a technique in which plants are grown, literally, through a mesh or screen.

Cannabis plants flowering in a SCROG setup

Cannabis plants flowering in a SCROG setup

Let’s explain a bit more about this growing system.

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.

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

Lower part detail

Lower part detail

The Screen of Green method

The Screen of Green method

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.

Mostly Sativa plants easily cover all the available space

Mostly Sativa plants easily cover all the available space

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.

January 9, 2015 | Marijuana growing systems
22 Comments


22 comments on “The SCROG cannabis growing system

  1. Tim

    Will it be ok to scrog plants grown in a nft tank .the thing is I got 3 seedlings mazer feminised and 2 monster clones taken from flowering plants they have all rooted and are getting in to veging but there gona be all different heights if left alone so I’m thinking of scroging them get a bed of tops same height and flower Does anyone no if this makes sense thanks tim.b.

    1. Dani Alchimia Post author

      Hi Tim,

      No problem at all, you’ll have a more uniform canopy and light spread will be improved. It is a great method to use when you grow strains with different growth patterns (much better than the SOG technique if that’s the case).

      Hope it helped!

  2. James Beck

    Can you grow outdoors; in single pots, with the same satisfaction/results ? Thx.

  3. Allen

    I’m 6 weeks into veg and want to scrog. I have 4 plants but they’re not giving hints on sex. Any advice

    1. Dani Alchimia Post author

      Hi Allen,

      It is not unusual that plants do not show their sex until the start of the bloom period, do not worry about that. Normally, with the Scrog technique you’d only use clones or feminised seeds, so you make sure that you won’t have to remove any plant once into bloom. The Sog system is much easier if you’re using regular seeds.

      If your plants already have the mesh and are ready to bloom, simply switch to 12/12 and remove any male asap. Once removed, fill the available space with your remaining plants.

      Hope it helped!

  4. Sleepy

    When is the best time to put the screen up? I have three plants, so far, in a 2ft x 2ft x 4ft tent. Two are sprouts about 3 inches and the other is germinated in a peat plug and is starting to root so it’ll be behind the other two in growth, not to mention another 2 that are germination in water and havent been added to tent yet, anyhow, is it too early to put a screen up or should I wait till they get about teenage size? Any help is appreciated. T.I.A.

    1. Tim Alchimia

      Hi Sleepy, thanks for your question. First you need to decide at what height you’ll position the mesh screen. To make things as comfortable as possible you’ll want to fit the screen before the biggest plants reach that height, but not too early in the grow as the net will make your access more difficult, so there’s no point in putting it in there before it’s needed. Depending on the genetics being used, personally I’d do some apical pruning at the height where I want the plants to branch out and once I started to see new growth and significant branching I’d fit the screen at the appropriate height for the new branches to grow through. I hope that’s some help, happy growing!

  5. Lumpy

    If im scrogging outdoors, for height/stealth reasons, i don’t have as much control on when the plant starts too flower, how long do i keep laying branches down for? As my screen might never get full as i cant control the light cycle…

    1. Tim Alchimia

      Hi Lumpy, thanks for your comment and question. It depends on where in the world you are growing and at what point in the summer your plants will be triggered to flower. Here, at around 43ºN, I’ve calculated that around 15th August is the moment when my plants will have enough natural darkness (over 14 hours) to trigger flowering, so I stop any pruning about 2 weeks before that point to allow the plants to recover before flowering, although you could probably keep on scrogging for a bit longer while taking a lot of care not to damage anything, which could stress the plants, set them back and eventually delay harvest. I hope that’s helped, all the best for the season ahead and happy growing!

  6. Medical Marijuana

    Very useful article. Through reading this lot of information about scrog of Marijuana and its helpful.

  7. Mathieu

    Hello, i wanted to ask about the tucking and bending technique , how you guide the branches? Thanks for sharing

    1. Tim Alchimia

      Hi Mathieu, thanks for your question. It’s important to start guiding and tucking the branches when they’re still bendy and flexible, and before they become hard and woody. Then it’s simply a case of being very gentle and careful, trying not to bend any branches double, the best advice I can give is to go slowly, if a branch won’t bend all the way to where you want it to go, then bend it halfway, fix it with a tie and then the following day try and get it into the desired position.

      Usually all the bending and tying is done before flowering begins, and during the stretch period at the start of flowering, which is often when its most useful. I hope that’s a help to you, happy growing!

  8. Klitzy

    My plant is just about finished flowering it has nice buds that are super sticky and dence but when I check the trycomes there still just milky and it kinds seems like it’s just frozen in its state just wondering if there’s sumthin I can do or just wait it out

    1. Tim Alchimia

      Hi Klitzy, thanks for the comment and question. Those milky trichomes will eventually turn amber colour if you leave the plant to mature for long enough. That said, many growers prefer to harvest with milky heads, arguing that this is the peak maturity point, and amber heads are oxidised and degraded beyond their best, while clear trichomes have yet to come to maturity. It’s up to you, but if you want amber, you’ll have to wait it out! All the best and happy harvesting!

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