How to germinate cannabis seeds: three methods, timing and mistakes.
Mr.GramGram · 14 June 2026 · 7 min read
Germination is the most common beginner question and the stage where most seeds are lost. The good news: the process itself is simple, and almost every failure comes down to three mistakes. Let us go through the methods, the timing and what actually goes wrong.
What a seed needs.
Three things only: moisture, warmth and air. Moisture softens the shell and starts the metabolism; warmth sets the pace; oxygen lets the embryo breathe. Light is not needed at all at this stage — and it is usually the attempt to give “more” of one of the three that ruins everything.
| Condition | Target | What happens if it is off |
|---|---|---|
| Temperature | 20–25 °C | below 18 °C it stalls; above 30 °C the embryo dies |
| Moisture | damp, not wet | sitting in water, the seed suffocates and rots |
| Air | free access | a sealed container with no exchange grows mould |
| Light | not needed | direct light dries the substrate out |
Method 1. Paper towel.
- Wet the towel and wring it out — it should be damp, not dripping.
- Lay the seeds out, cover with a second layer, put it between two plates or into a container.
- Keep it dark at 20–25 °C. Open it for a minute once a day — that is the air part.
- As soon as the taproot is 2–5 mm, plant it. Waiting longer is pointless: a long root is fragile and breaks easily.
The upside is that you can see what is happening. The downside is an extra transplant and the risk of damaging the root.
Method 2. Glass of water.
Soak for 12–18 hours in room-temperature water. Never go past 24 hours: the seed stops getting oxygen and drowns. The method suits older seeds with a hard shell, which it softens. After soaking, seeds move to a paper towel or straight into soil.
Method 3. Straight into soil.
The gentlest option: the root is never touched. Plant 5–10 mm deep in damp substrate and do not press anything down on top. Seedlings appear on day 3–7. The one drawback is that you cannot see what is going on, so a failure leaves you guessing at which stage it happened.
Which way up.
The taproot emerges from the pointed end, so the convention is to plant pointed end down. Its importance is heavily overstated, though: the root will turn itself, orienting by water and light rather than by “down”. See our piece on geotropism — gravity has nothing to do with it. If in doubt, lay the seed on its side; that always works.
How long to wait.
Fresh seeds crack in 24–72 hours. Up to 5 days is a normal spread. Older or dried-out seeds may take 7–10 days, and that is still not a verdict. Do not throw anything away before two weeks.
Why seeds fail to sprout.
- Overwatering — reason number one. A seed sitting in water suffocates. Damp, not wet.
- Cold. At 15–18 °C the process simply stalls while the seed stays alive.
- Too deep. More than a centimetre and the sprout will not make it up.
- Poor storage before sowing. Warmth and light kill viability within months — we cover that separately.
- Too much handling. Every “let me check on it” means drying out and mechanical damage.
Questions and answers.
How long do cannabis seeds take to germinate?
Fresh seeds take 24–72 hours, with up to 5 days being a normal spread. Older seeds can take 7–10 days. Do not write a seed off before two weeks.
Which way up should a seed be planted?
The convention is pointed end down, since the taproot emerges there. But the root orients by water and light rather than gravity, so a seed laid on its side germinates fine too.
Why are my seeds not germinating?
Most often overwatering: sitting in water, the embryo suffocates. Next in frequency come cold below 18 °C, planting too deep and poor storage before sowing.
What do I do right after a seed cracks?
Plant it once the taproot is 2–5 mm, 5–10 mm deep, root pointing down. A long root is fragile, so do not delay the transplant.