SCROG (Screen of Green) uses a horizontal net to spread and flatten the canopy so every bud site gets equal light. Instead of one tall cola with shaded lowers, you get a carpet of even tops — each one a potential top-shelf nug.
It's the single best technique for maximizing yield per watt in a fixed space.
Why SCROG works
Light obeys the inverse square law: double the distance, quarter the intensity. A 3-foot-tall plant gets strong light at the top and weak light at the bottom. SCROG eliminates this by making the canopy flat — every bud site is the same distance from the light.
The result:
- More even bud development (fewer "popcorn" lowers).
- Better light efficiency (your wattage covers the whole canopy equally).
- Better airflow under the net (less mold risk).
- Higher total yield from the same space and light.
What you need
- Trellis netting (4x4 or 4x8, ~4" squares) — plastic or string both work.
- A frame — PVC pipes, bamboo stakes, or just hook the net to tent poles.
- One topped/trained plant per 2x2 area (or 2 plants in a 2x4, 4 in a 4x4).
The net should be mounted 8–12 inches above the pot rim — high enough that you can water and work under it, low enough that branches reach it in veg.
The SCROG process
Step 1: Top early
Top the main stem at the 4th–5th node. This splits growth into two main branches, which split again into four, then eight. The goal is many even branches, not one dominant cola.
Step 2: Mount the screen
Set the trellis net at 8–12" above the pots before the branches reach it. Tighten it so it doesn't sag.
Step 3: Weave during veg
As branches grow through the net squares, gently tuck them back under the net and guide them horizontally toward empty squares. Don't let any branch grow above the net.
- Fill 60–70% of the squares before flipping to 12/12.
- Weave every 2–3 days during active veg.
- Direct branches outward from center — fill the edges of the net.
Step 4: Flip to flower
Once the net is 60–70% full, flip to 12/12. The stretch (first 2–3 weeks of flower) will fill the remaining 30–40%.
Step 5: Stop weaving at week 2–3 of flower
Once the stretch slows, let bud sites grow up through the net. From here, they grow vertically above the screen — this is your bud zone.
Step 6: Lollipop below the net
Everything below the screen gets no light. Remove all growth below the net — small branches, fan leaves, sucker shoots. All energy goes to the canopy above.
How many plants per SCROG?
| Space | Plants | Veg time |
|---|---|---|
| 2x2 | 1 | 6–8 weeks (long veg to fill) |
| 2x4 | 1–2 | 5–7 weeks |
| 4x4 | 2–4 | 4–6 weeks |
| 4x8 | 4–6 | 4–6 weeks |
Fewer plants = longer veg time to fill the screen. More plants = faster coverage but more crowded root zones. 2 plants in a 4x4 is the sweet spot for most home growers.
SCROG + LST vs. SCROG alone
SCROG is LST — the screen replaces the ties. You can combine: use soft ties for early-veg training, then transition to the screen once branches are long enough to weave. Most growers do some tie-down LST in weeks 1–3 before the screen takes over.
Common mistakes
- Flipping too early. If the screen is only 40% full at the flip, you'll have bare spots that produce nothing.
- Not weaving often enough. A branch that pokes through the net and grows 6 inches vertical is hard to bend back. Weave every 2–3 days.
- Screen too high. If the net is 18+ inches above the pot, branches waste energy growing to reach it. 8–12" is the range.
- Not lollipopping below. The whole point of SCROG is concentrating energy in the canopy. Growth below the screen is wasted.
- Using autos. SCROG needs a long veg period and the ability to control when you flip — photoperiods only.
Expected yield boost
A well-executed SCROG in a 4x4 under 600W of good LED light can yield 1.5–2 grams per watt (900–1200g). Without SCROG, the same setup typically yields 0.8–1.2 g/watt.
The boost comes entirely from better light distribution — you're not growing more plant, you're growing it more efficiently.