You’ve done your shopping, asked all the right questions and selected the cannabis strain that’s perfect for YOU. The next question is, how do you make the most of your grow? How do you produce the heavy yields that will keep you in fresh, homegrown marijuana for months at a time? There are lots of ways but one of the most popular and easy is to set up a scrog grow. This is a method of training your plants to grow horizontally, increasing bud sites and boosting yields. Unlike the Sea of Green method, a SCROG makes the most of fewer plants while still maximizing space.
Tip: you can compare Screen of Green to Sea of Green by checking out this article: SOG vs SCROG.
Before we start…
When growing cannabis at home, it’s important to know the law and how many plants you can grow recreationally and medicinally. In California, you’re limited to six plants per household for recreation, twenty-four for medicinal (but you will need the okay from your doctor). These rules are not universal so make sure you check the law in your own state before you even think about growing cannabis at home.
With these limitations in mind, it’s important to make the most of the few plants you ARE permitted to grow. One of the best ways to do this is to employ a Screen of Green (SCROG). Here’s how it works.
Screen of green: what is SCROG?
This yield-boosting technique makes use of a lightweight mesh or scrog screen, usually trellis. You train your plants to grow horizontally using a method of weaving the branches, making sure leaves and nodes are not strangled. As the plants grow through the holes, the tops are pulled back through and under and allowed to grow up again, before the process is repeated.
Once the plants adapt to growing horizontally, they will create a thick upper canopy blocking most of the light from anything growing underneath. Airflow improves around the thinned-out stems and the plant’s energy is diverted to the bud-laden upper canopy. When executed correctly, this improves yield by essentially making a single tree produce the same yield as multiple indoor cannabis plants.
The Screen of Green method (or scrogging, for those in the know), is a great way to increase yields when growing cannabis indoors. You can produce up to three times more bud WITHOUT sacrificing quality. Let’s take a look at the important things to remember when considering a SCROG.
Tip: It gets easier with each individual SCROG you execute.
Increasing yields using the SCROG method
1. Choose the right type of cannabis seed: the best strains to SCROG
Most modern hybrids are capable of producing a high yield and lend themselves well the SCROG technique. Auto-flowering seeds should be discounted. Their extremely rapid growth rate leaves no time for any real training, and an autoflower scrog is rarely successful. Your best bet to SCROG marijuana is a robust, sativa-dominant strain.
Top five strains for a SCROG
- Jack Herer: a vigorous, heavy-yielding plant with lots of stretch.
- Amnesia: can yield in excess of 24 oz per plant in a SCROG.
- AK47: stretches up to 200% – ideal for a screen of green.
- Pineapple Haze: fresh smells and a full screen.
- Bruce Banner x Kali Mist: prepare for some monstrous yields.
2. Understand the growth stages
Different strains have different growth rates and attributes, requiring a separate time allotment for the vegetative and flowering stages.
With a SCROG setup, the vegetative phase tends to be a little different than the standard 6 to 8 weeks from seed. Shorter, indica-dominant hybrids need an additional week in the vegetative stage to fully occupy the space in the screen. Sativa strains, by contrast, grow faster and most will take a week less than usual to fill the screen.
Since Indica strains spend more time in the vegetative stage, they will most likely fill the screen as early as the beginning of the third week. The colas should now be allowed to grow vertically. Once 80% of the screen is filled, it’s time to flip your plants into flower.
Sativa strains, on the other hand, might need constant bending and weaving until around the fifth week of the bloom cycle. They tend to grow tall and need to be evenly spread out along the horizontal to prevent the colas getting too close to your lights. By the last week of the bloom cycle, the growing area should be covered entirely with large, evenly-distributed colas.
3. How to build a SCROG
Setting up SCROG is surprisingly easy and straightforward. You won’t need a PHD in engineering but you will need to have everything prepared before you begin.
Materials needed for a SCROG kit:
- Screen with 4 to 5-inch diameter holes; cotton works better than plastic/vinyl.
- Plastic plant ties or string.
- Young cannabis plants that need no further transplanting.
- Pre-prepared growing space.
- Position and suspend the screen 8 inches above the branch tips. Keep it as close as possible to the light source while leaving enough room for the buds.
- Work towards 12 square inches of screen per plant.
- As the plants gain height, gently tuck the branches through the screen. Allow only the top canopy to peek through the mesh. You can weave the branches into the trellis.
- If necessary, use plant ties or string to secure the branches/tips.
- Continue training the plants until most of the screen is covered. For Sativa strains, aim for 60% coverage, 80% for Indica. Once the desired coverage is achieved, switch the light cycle to trigger the flowering phase.
- As the plants grow, continually fill the remaining spaces in the screen.
- Monitor the plants frequently and make sure the branches under the canopy are regularly pruned. This will allow the plants to focus their energy on developing healthy, dense nugs above the screen.
4. Topping and node pruning
There are two pruning techniques that can really help with a SCROG: topping and node pruning.
This entails snipping the top of the main stem to encourage two colas to grow instead of one. Topping helps make plants grow shorter and bushier which is perfect for scrogging.
Topping is best done when the plant is at least 12 inches in height, but even premature plants can be pruned by pinching off the top of the main shoot between the fingers.
Topping can be used on a single plant multiple times, depending on how long you intend to keep it in veg. Let them grow at least a week between each topping to avoid overly stressing the plant.
This technique helps increase the number of high-quality buds. Node pruning allows plants to focus their energy on producing larger buds instead of multiple, popcorn colas. It involves removing all of the nodes besides the top three, with the remaining nodes growing around 80% faster. Thinning out plants like this is vital before flipping into flower because you don’t want nodes and branches crowding each other, draining energy and promoting mold.
De-noding is best done first in veg when plants have become bushy/overgrown. Remove every node to the tip, leaving the leaves. Flip the plants within a week of pruning and indicas are ready to go. Sativas may need a clean-up after a week or two of flowering. But leaving three nodes from the tip this time.
5. Maintaining your SCROG
Once the grow space is set up and the plants are weaving well into the screen, it is vital to keep the plants healthy by maintaining good growing conditions.
Humidity & air circulation
Keeping an eye on humidity is vital to any indoor grow, even more so when employing a SCROG. Scrogging produces tightly-packed plants with dense colas and thick bushes. This makes them more susceptible to molds and mildew.
Install a dehumidifier and keep the grow as ventilated as possible, making sure your A/C and fans are working properly. There should always a light breeze circulating over and around the canopy.
Hydration is key. Only water the plants when the soil is almost (but never completely) dry. Overwatering invites mold, mildew, pests and other pathogens that can damage the plants. Underwatering, on the other hand, will lead to wilting and poor health and is just as harmful.
To determine when it’s time to water, dip a finger about two inches into the soil. If the soil is still wet two inches down, it’s too damp to water and you can try again in 24 hours. It’s best to keep the pH level of the water around 6.3 for soil and 5.8 for hydro.
Tip: always cycle wet to dry using Kyle’s watering methodology.
The SCROG cannabis growing system
Screen of Green, when executed correctly, will guarantee bigger harvests with fewer plants. Setting it up is straightforward and the results are extremely rewarding. Please get in touch if you have any questions about how to set up a SCROG, or if you would like to know more about how to SCROG to maximize yields. We are always here to help.
FAQs: The Screen of Green method (SCROG)
- What size container should be used when using SCROG method? This depends on the size of your grow area. You want no more than one plant for every 12 square inches of screen but you want a big root system. You should be fine with 5 or 7 gallon pots.
- Will scrogging guarantee heavier yields? When executed correctly, yes. But don’t compromise on environmental conditions. You need to get as much right as possible no matter what growing method you choose.
- How close can I keep the lights? As close as is safe! Light burn can be very damaging so keeping your lights close needs constant monitoring.
- How high does the screen need to be? One to two foot is standard for SCROG height, but this is down to you – your preferences, your needs. Just remember, the higher the screen, the more pruning you’ll need to do below.
- Can you make your own screen? Making your own SCROG netting is pretty simple. Make a square frame and tie string at right angles like a chess board, with the ‘holes’ around 4 – 5 inch squares.
- Can you set up an outdoor SCROG? Yes, simply follow the same principles as an indoor SCROG.