# SCROG: screen of green

> SCROG uses a horizontal net 20–40 cm above the pots to spread a few plants into a flat, even canopy: shoots are tucked under the net through veg and early stretch, then allowed to grow up through it. It suits small rooms and plant-count limits, at the cost of longer veg. Fill about 70–80 % of the net before flipping, since plants stretch to fill the rest.

- Canonical: https://genetixbay.com/knowledge/training/scrog.html
- Category: Training · Level: Intermediate
- Evidence: Grower practice · Status: Draft: awaiting expert review
- Stage: Veg, Transition, Flower · Systems: Any system
- Updated: 2026-10-31 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Questions and answers

**How does SCROG work?** SCROG (screen of green) works by fixing a horizontal net above the pots and tucking every shoot that pokes through back under it, sideways, throughout veg. The plant spreads across the screen into a flat, even canopy where all the [tops](https://genetixbay.com/knowledge/glossary/top-shelf.md) sit in good light. After the flip, growers keep tucking for about two weeks of [stretch](https://genetixbay.com/knowledge/glossary/stretch.md), then let the tops grow up through the net.

**How high should the SCROG net be?** Set a SCROG net about 20-40 cm (8-16 in) above the pots, with mesh squares of 5-10 cm (2-4 in). Install it taut and level before the plant reaches it. For heavy colas, a second net about 20-30 cm higher adds support in flower. Below the net, strip small shaded growth around day 21 of flower to reduce larf and mould risk.

**When do I flip a SCROG to flower?** Flip a SCROG to [12/12](https://genetixbay.com/knowledge/glossary/12-12.md) when the net is about 70-80% full. Many cultivars stretch 1.5-2.5 times after the flip, and that stretch fills the remaining space; flipping with a full net leaves you out of room. Keep tucking sideways for the first 10-14 days of stretch, then let the tops grow up through the screen.

**SCROG vs [SOG](https://genetixbay.com/knowledge/glossary/sog.md): which yields more?** No published head-to-head trial shows whether SCROG or SOG yields more. In both, light and canopy evenness drive yield, and research shows [planting density](https://genetixbay.com/knowledge/glossary/plant-density.md) strongly affects yield per area and cannabinoid uniformity. SCROG gets a few plants, about 1-4 per m², to fill a space, which suits plant-count limits but adds [veg time](https://genetixbay.com/knowledge/glossary/veg-time.md) and labour.

**How many plants for a SCROG?** A SCROG typically uses 1-4 cannabis plants per square metre, or one plant per 0.25-1 m², with 4-8 weeks of veg depending on [pot size](https://genetixbay.com/knowledge/glossary/pot-size.md) and space. Fewer plants means longer veg to fill the net, which suits plant-count limits but costs more time and power. Where plant numbers aren't limited, using too few plants for the space is a common mistake.

**Short answer.** Fix a net (5–10 cm / 2–4 in squares) **20–40 cm (8–16 in)** above the pots. Through veg, tuck every shoot that pokes through back under, sideways, so the plant spreads across the screen. Flip to 12/12 when the net is **~70–80 % full**; tuck for the first **~2 weeks of stretch**, then let tops grow up. Below the net, strip small shaded growth ([lollipopping](https://genetixbay.com/knowledge/training/defoliation-lollipopping.md)). SCROG makes **few plants** fill a space evenly, which helps under plant-count limits; it trades extra veg time and labour for that. Head-to-head yield vs SOG is not published; light and canopy evenness drive both [1][3].

## How to do it

1. Top once or twice, then [LST](https://genetixbay.com/knowledge/glossary/lst.md) the branches outward ([topping](https://genetixbay.com/knowledge/training/topping.md), [LST](https://genetixbay.com/knowledge/training/lst.md)).
2. Install the net before the plant reaches it; make it taut and level.
3. Tuck daily or every other day; always tuck sideways along the net.
4. Flip at 70–80 % fill; tuck for 10–14 days of stretch.
5. Around day 21 of flower, remove growth below the net that gets little light.
6. A second net 20–30 cm higher supports heavy colas.

## Numbers that matter

| Item | Typical |
|---|---|
| Net height above pots | 20–40 cm (8–16 in) |
| Net mesh | 5–10 cm (2–4 in) |
| Plants per m² | 1–4 (1 per 0.25–1 m²) |
| Veg time | 4–8 weeks depending on pot size and space |
| Fill at flip | ~70–80 % |
| Stretch | Many cultivars stretch 1.5–2.5× after flip (*Grower practice*) |

## Common mistakes

- Flipping with a full net, then running out of space in stretch.
- Tucking upward or twisting stems.
- Leaving dense, dark growth under the net (larf and mould risk).
- Too few plants for the space under a plant-count-free setup (longer veg = more power).

## Evidence

The canopy-light rationale is *Supported* [1]; planting density strongly affects yield per area and uniformity [2][3]. SCROG technique and fill rules are *Grower practice*.

## Sources

1. Rodriguez-Morrison V, Llewellyn D, Zheng Y, 2021. Cannabis yield, potency, and leaf photosynthesis respond differently to increasing light levels in an indoor environment. Frontiers in Plant Science 12:646020. https://doi.org/10.3389/fpls.2021.646020
2. Danziger N, Bernstein N, 2022. Too dense or not too dense: higher planting density reduces cannabinoid uniformity but increases yield/area in drug-type medical cannabis. Frontiers in Plant Science 13:713481. https://doi.org/10.3389/fpls.2022.713481
3. Backer R, Schwinghamer T, Rosenbaum P, et al., 2019. Closing the yield gap for cannabis: a meta-analysis of factors determining cannabis yield. Frontiers in Plant Science 10:495. https://doi.org/10.3389/fpls.2019.00495