Learn How to ScrOG

By Rick Smith / September 25, 2021

White trellis net with even cannabis bud sites poking through under a grow light

Table of Contents

ScrOG stands for screen of green. You stretch a net or mesh horizontally above your plants and train the branches along it, so the canopy becomes a flat, even sheet of bud sites. The idea is simple: indoor lights lose strength with distance, so a flat canopy puts more buds at the same good distance from the light. Below, you will find how ScrOG works, how to set it up, and how to manage it through flower. It draws on Purdue University Extension research on light and Washington State University Extension guidance on plant supports. Before you start, check your state’s home grow law, including plant limits.

Why a flat canopy helps

Purdue University Extension explains that horticultural researchers measure light for plants in micromoles per square meter per second, a unit that “quantifies the number of photons (individual particles of energy) used in photosynthesis that fall on a square meter (10.8 square feet) every second.” It also explains that the daily light integral, or DLI, “is the amount of PAR received each day as a function of light intensity” and “duration.”

Under a grow light, the tops of tall branches sit closer to the lamp than lower branches. Growers use ScrOG to even that out. When all the bud sites sit at about the same height, each one gets a more similar share of light, and growers commonly report fewer small, airy buds in the shade below. That last part is grower experience, not a Purdue finding.

Why support matters

A screen also holds branches up. Washington State University Extension notes, about tomato supports, that you should “use ones that are robust enough and tall enough to support your tomato plant at maturity.” The same logic applies to cannabis in flower: heavy colas can bend or snap without support, and a screen spreads that weight.

When ScrOG helps, and when it does not

ScrOG suits photoperiod plants in a tent or small room with a fixed light, where you can control when flowering starts. It is less suited to autoflowers, which have a short veg period and less time to fill a screen, and to outdoor plants under the sun, where light comes from a moving source. Many outdoor growers use netting for support only.

What you need

A net or mesh with openings of about 2 to 3 inches (5 to 8 cm). Plastic trellis netting or a homemade frame with string both work.
A way to anchor the net firmly to the tent poles or a frame.
Plant ties or soft wire.
Photoperiod plants, often one to four in a typical home tent.

How to set up a ScrOG: step by step

Choose your plant count. Fewer plants take longer to fill the screen. More plants fill it faster. Stay within your state’s limit.
Top the plants early. Topping once or twice in veg makes several main stems instead of one tall one.
Install the screen. Set it about 8 to 12 inches (20 to 30 cm) above the pots or soil. Pull it tight and fix it at every corner.
Tuck as plants grow. When a branch tip grows 2 to 4 inches above the net, gently bend it back under and move it one square over toward an empty spot.
Spread evenly. Aim to fill every square with one growing tip.
Flip to flower when about 70 to 80% of the screen is full. Plants usually stretch after the flip and will fill the rest. This share is common grower practice.
Keep tucking for one to two weeks after the flip. Stop tucking once flowers start to form, then let tops grow straight up.
Clean up below the screen. Remove small shoots and leaves under the net that get little light. This improves airflow under the canopy.
Keep the light at a steady distance. Follow your light maker’s guidance for height above a flat canopy.

A simple weaving calendar

Phase	What to do
Early veg	Top once or twice, let plants recover
Late veg	Install screen, tuck tips daily or every other day
Flip	Switch to 12/12 at about 70 to 80% screen coverage
Flower weeks 1 to 2	Keep tucking during the stretch
Flower week 3 onward	Stop tucking, remove growth under the net
Late flower	Support heavy colas, watch for bud rot

ScrOG vs SoG

People sometimes mix up ScrOG with SoG, or sea of green. SoG uses many small plants flipped to flower early, each producing one main cola, packed close together. ScrOG uses fewer plants, trained wide over a longer veg. SoG needs more plants, which can run into state plant limits. ScrOG spreads fewer plants across the light but takes more time and hands on work.

Pot size and veg time

Bigger pots support bigger root systems and longer veg times, which suit filling a screen with one or two plants. Small pots limit how far each plant can spread. As a rough guide, the fewer plants under the screen, the longer the veg and the larger the pot you will want. Keep in mind that a longer veg means a longer total grow.

Training safely

Bend stems slowly and gently. If a stem cracks, growers often tape it for support, but a badly cracked stem may not recover. Wear gloves if your skin reacts to sap. Keep scissors clean when trimming lower growth, and throw away any leaves with signs of mold or disease rather than leaving them in the grow space.

Troubleshooting ScrOG problems

Branches snapped when tucking. Tuck earlier while stems are flexible, and bend near the base of new growth.

Screen filled too fast and plants outgrew the tent. Flip sooner next time, around 60 to 70% coverage, since stretch can double height.

Buds under the screen are small and airy. That is expected. Prune lower shoots in the first weeks of flower so energy goes to tops.

Humidity rose under the dense canopy. Add a small fan below the screen and remove more lower leaves. If you find gray fuzz or brown mush in buds, remove and throw away the affected material and do not use it.

Uneven canopy, with a few tall tops. Gently bend or super crop those tops early in the stretch to level them.

Related guides

Pair ScrOG with steady light intensity in flowering, learn when to flip to flower, and see our defoliation guide.

FAQ

What does ScrOG mean?

ScrOG means screen of green. You train cannabis branches along a horizontal net so the canopy becomes flat and even under the light.

When should I flip to flower in a ScrOG?

Many growers flip when the screen is about 70 to 80% full, because plants stretch after the flip and fill the rest. If space is tight, flip sooner.

How high should a ScrOG screen be?

A common starting point is about 8 to 12 inches (20 to 30 cm) above the pots or soil, with enough room above for the stretch and your light.

Can you ScrOG autoflowers?

You can, but it is harder. Autoflowers have a short veg period, so they may not fill a screen before flowering. Many growers use gentle bending instead.