How to Build a SCROG Net for Cannabis: Frame and Mesh

Quick answer

Build a 4 ft by 4 ft frame from 3/4-inch PVC pipe. Cut four legs. String 3-inch squares across the top. Set the net 8 to 10 inches above the pot rim. Tuck shoots under the mesh during veg. Flip to 12/12 when the screen is 70 to 80 percent full.

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Materials

• Three 10 ft lengths of 3/4-inch PVC pipe
• Four 3/4-inch 90-degree PVC elbows
• PVC primer and cement
• 200 ft of 3/16-inch braided nylon line
• Zip ties
• Tape measure, marker, PVC cutter, scissors

Step 1: Cut and glue the frame

1. Cut four 48-inch sections for the sides.
2. Cut four leg sections. For a 12-inch pot, cut legs at 22 inches. The screen should sit 8 to 10 inches above the pot rim.
3. Glue the four sides into a square with the elbows and PVC cement. Measure both diagonals. They should match.
4. Attach one leg to each corner with two zip ties per leg. Set the frame over the pot. Legs go outside the pot footprint.

Step 2: String the mesh

1. Mark 3-inch intervals on all four sides. A 4 ft side takes 16 marks.
2. Tie the line to a corner. Wrap it around the frame at each mark and pull it by hand until the line sits straight.
3. Run the first set of lines parallel to one side. Add a 1-inch screw at each mark if the line slips on the PVC.
4. Run the second set at 90 degrees. Weave over and under at each crossing.

Use 3-inch squares for most plants. Use 2-inch squares for small plants in a 2 ft by 2 ft space. A 4-inch mesh lets shoots drop back below the screen.

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Step 3: Set the height

Set the screen 8 to 10 inches above the pot rim for plants that finish under 4 ft. Set it 12 to 18 inches above the rim for tall sativa plants. A net set higher than 18 inches leaves the lower stems in shade.

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Training schedule

• Week 1 to 2 of veg: tuck the main stem under the mesh. Let side shoots rise.
• Week 3: tuck shoots every 2 to 3 days.
• Week 4 to 5: flip to 12/12 when the screen is 70 to 80 percent full.
• Flower stretch: keep tucking for the first 2 to 3 weeks after the flip.

Common mistakes

• Mesh over 4 inches: shoots fall through and the canopy stays uneven.
• Net set above 18 inches: lower nodes get little light.
• Screen filled past 90 percent before the flip: stretch growth has no room.
• Jute twine: it sags when wet. Nylon holds tension.

Add a second net

Add a second frame 8 inches above the first for heavy colas. The top net holds buds upright in late flower. Zip tie both frames to the same legs.