Pick First
Paper towel germination is the better choice for seed older than 12 months, for seed of unknown viability, and for growers who want a count of germinated seed before planting. Direct sowing is the better choice for autoflowering seed and for growers who plant in the final container.
Paper Towel Method
Wet two paper towels with water at pH 6.0 to 7.0. Wring out surplus water. Place the seed between the layers. Put the stack in a sealed bag or between two plates. Hold at 70 to 80 F (21 to 27 C). Check the seed each 12 to 24 hours.
- Radicle shows in 24 to 72 hours.
- Transplant when the taproot reaches 0.5 to 1 inch (1.3 to 2.5 cm).
- The seed shell stays in the towel in most cases.
Risks: root breakage during transfer, mold on a wet towel, and shock when the taproot meets new media.
Direct Sowing
Fill the final pot with moist media. Poke a hole 0.5 inch (1.3 cm) deep. Place the seed, cover it, and mist the surface. Hold at 70 to 80 F. Seedlings break the surface in 3 to 10 days.
- No root handling.
- Roots grow into the final media from day one.
- Failures stay hidden for 7 to 10 days.
Risks: damping off from wet media, low media temperature, and a crusted surface that blocks the shoot.
Side by Side
- Time to visible root: paper towel 24 to 72 hours; direct sow 3 to 10 days for the shoot.
- Handling: paper towel needs one transfer; direct sow needs none.
- Viability count: paper towel shows the number; direct sow does not.
- Mold risk: higher with paper towel if the towel stays wet.
- Autoflowers: direct sow lowers transplant stress during a short veg window.
Seed Age and Water
Seed stored at 40 F (4 C) and 30 to 40 percent humidity holds viability for 2 to 5 years. Seed at room temperature loses viability in 12 to 18 months. Soak seed 12 to 24 hours before either method to cut the time to radicle by about 24 hours. Use water at pH 6.0 to 7.0. Add 1 percent hydrogen peroxide to the towel water if mold appears.
Germination of cannabis seed is regulated in some US states. Check state law before you start.