How to germinate cannabis seeds (and what to do if they don’t)

Cold, waterlogging, planting depth, and old or poor-quality seed can all cause germination problems.

Three common methods

• Straight into the medium. Put the seed in a moist starter plug or small pot. If a root is already showing, point it downward without touching or bending it. An unsprouted seed doesn’t need a guessed “pointing down” orientation. This means the least handling, so the least risk of damaging the root.
• Paper towel. Put the seed between damp (not dripping) towels in a warm spot. Move it to the medium as soon as a short white root appears.
• Soak first. Give it a short soak in room-temperature water, up to about a day, then plant. Don’t leave seeds soaking for days.

The basics

1. Warmth. About 75 to 80°F is the usual target. Cold slows everything down and invites rot.
2. Moisture. Damp like a wrung-out sponge. Soggy media starves the seed of air.
3. Depth. Roughly a quarter to half an inch.
4. Drainage. Use containers with drainage holes.
5. Light. As soon as the sprout appears, give it gentle light so it doesn’t stretch.

If a seed doesn’t sprout

• Nothing after a week: check the temperature first. Old seeds may be slow.
• Seed went soft or mushy: too wet. Start again with a drier medium.
• Sprout appeared, then disappeared: check for drying out, damping off or physical damage. Keep the root zone evenly moist, not just the surface. Misting alone may leave the medium dry underneath.
• Seed shell stuck on the leaves: add a few drops of water to soften it and let it fall off on its own. If you help, be very gentle.

Storing seeds

Cool, dark and dry is the general rule. The common approach is a sealed container in the refrigerator, brought to room temperature before you open it.

These cannabis temperature, depth and timing ranges are common starting points, not a guarantee for every seed lot. Use a thermostatically controlled propagation mat only as directed, and check the medium’s temperature instead of assuming room temperature is enough.