Cannabis SCROG Setup With a PVC Frame
A SCROG, or screen of green, uses a horizontal net to hold branches flat so the whole canopy sits at one height under the lamp. A PVC frame is the cheap and adjustable way to hold that net. Build a rectangle from 1/2-inch pipe, stretch trellis netting across it, and set the screen 8 to 12 inches above the top of your pots before the plants start to stretch.
how many plants under a scrog screen
What You Need
- 1/2-inch schedule 40 PVC pipe, about 12 linear feet for a 4x4 space
- Four PVC elbows and four PVC tees
- 1/2-inch self-tapping screws or 6-inch zip ties
- Trellis netting with 3.5-inch or 4-inch mesh, cut slightly larger than the frame
- Hacksaw or PVC ratchet cutter, tape measure, marker, cordless drill with a 3/16-inch bit
Build the PVC Frame
- Measure the inside width and depth of the grow tent or room, then subtract 2 inches from each number for wall clearance.
- Cut two pipes to the width measurement and two to the depth measurement.
- Scrape the burr off each cut end with the back of the cutter or a scrap of sandpaper.
- Dry-fit the four rails into elbow fittings to form a rectangle, and check that it sits inside the space without touching the walls.
- Cut four leg pipes at pot height plus 10 inches, so the finished screen lands in the 8 to 12 inch range above the pots.
- Swap each corner elbow for a tee, then push a leg into the open socket at every corner.
- Drill a 3/16-inch pilot hole through each fitting where it meets a pipe.
- Drive one self-tapping screw into each hole to lock the joints. Zip ties work as well if you plan to break the frame down between runs.
- Mark the top rails every 4 inches with the marker.
- Drill a 3/16-inch hole at each mark, or skip this step and wrap small zip ties around the pipe instead.
- Lay the netting over the frame and hook each mesh corner onto a screw or zip tie, working from the center outward.
- Pull the netting until a finger press sinks about half an inch and no slack sits in the middle.
- Set the frame over the plants and confirm the screen rests on the legs, not on the pots or the plant stems.
Train Plants Through the Screen
- Wait until each plant has 4 to 6 nodes and the tallest branches reach the net.
- Push the top shoot under the nearest square, then let it rise again one square farther out.
- Repeat this tucking each day during stretch, moving the tallest growth toward the frame edges.
- Remove leaves and lower branches that sit under the screen and receive no direct light.
- Flip to flower when the screen is about 70 percent full, since plants keep stretching for the first two to three weeks of bloom.
Checks Before Flowering
Shake each corner of the frame. A loose leg means the screw missed the pipe wall, so add a second screw or a zip tie. Confirm the net squares still line up with the plant tops, and raise the frame with longer legs if the canopy has outgrown the 12 inch limit. Keep the pipe dry at the base so standing water in the fittings does not breed mold.