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). 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
- Top once or twice, then LST the branches outward (topping, LST).
- Install the net before the plant reaches it; make it taut and level.
- Tuck daily or every other day; always tuck sideways along the net.
- Flip at 70–80 % fill; tuck for 10–14 days of stretch.
- Around day 21 of flower, remove growth below the net that gets little light.
- 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.
12/12 is the classic flowering schedule for photoperiod cannabis: 12 hours of light and 12 hours of uninterrupted darkness, which triggers and sustains flowering.The stretch is the rapid increase in height in the first two to three weeks after switching to flower, when many cultivars grow 1.5 to 3 times taller.Top shelf is the highest price tier of flower in a shop, used as slang for any premium-looking cannabis; it reflects pricing and appearance, not verified quality.SCROG (screen of green) trains a few plants under a horizontal net, tucking shoots so the canopy forms a flat, evenly lit layer of many tops.Veg time is how long a photoperiod plant is kept in vegetative growth under long days before being flipped to flower, which largely sets its final size.SOG (sea of green) grows many small plants at high density with little or no veg time, each making one main cola, to shorten the cycle.LST (low-stress training) bends and ties stems so the plant grows wide and flat, exposing more bud sites to light without cutting or breaking tissue.The dense, elongated cluster of flowers that forms at the end of a stem or branch; the main cola tops the leader.Plant density is the number of plants per unit of canopy area; more plants raise yield per area up to a point but shorten veg and reduce uniformity.Pot size is the volume of medium a plant roots into; bigger pots give bigger plants within reason, but feeding frequency can let small pots punch well above their size.
