How to Germinate Cannabis Seeds (Paper Towel Method)

My first seed, I left in a glass of water for three days because if a bit of soaking is good, more must be better. It came out soft, grey and dead — a tequila-in-2004 sort of lesson. Germination isn’t complicated, but it punishes both impatience and over-care. Here’s the method I use and recommend at the shop counter, step by step.

The short version:

• Soak 12–18 hours in room-temperature water — no longer
• Move to a damp paper towel between two plates: dark, warm, humid
• Keep it around 25°C and moist, not soggy — the seed needs oxygen too
• A white taproot appears in 24–72 hours (some take up to 7 days)
• Plant when the taproot is 0.5–1cm, taproot pointing down, 1cm deep

Want the full breakdown? Keep scrolling.

Step 1 — soak the seed

Drop your seeds in a glass of room-temperature water for 12 to 18 hours. That’s enough to soften the shell and wake the hormones inside — not the three days that turned my first one to mush. If a seed sinks, grand. If it still floats at 18 hours, give it a gentle tap; plenty float and germinate fine anyway, so don’t read tea leaves into it. The single most common germination mistake is leaving seeds in water too long: every hour past about 24 raises the rot risk, and you can’t see what’s happening inside the shell.

Step 2 — the paper towel

Lay the soaked seeds on a damp paper towel on a plate, fold it over, and put a second plate on top upside down, like a clamshell. That keeps it dark, warm and humid — the three things germination needs. Sit it somewhere warm: on top of the fridge, near a radiator, or on a heat mat if your house runs cool (a mat isn’t essential — my first successful seeds went off on top of the fridge — but it removes a variable). Around 25°C is the sweet spot. Check every 12 hours, not every hour. The towel should be damp, not flooded — if it’s drying, add a splash; if there’s standing water, tip it off. Moist and airy, the same oxygen lesson as overwatering: drown it and it rots, dry it out and the taproot dies.

Step 3 — read the taproot, then plant

Within 24 to 72 hours you should see a small white root push out of the cracked shell — the taproot. If nothing’s happened by day three, don’t bin it; some seeds, especially older or harder-shelled ones, take up to a week. Only call it dead if it’s gone soft and mushy or completely unchanged after seven full days. Plant when the taproot is about half a centimetre to a centimetre — don’t let it grow three inches and tangle in the towel, because peeling a fragile root off dry kitchen roll without snapping it is a miserable job. Make a 1cm hole in a small pot of light, unfertilised seed-starting mix, set the seed in taproot pointing down (unsure which way? lay it on its side, the root finds down on its own), cover lightly, and mist — don’t press it in hard or bury it deep. Then warm, gentle light, and hands off.

Why this method over the others?

Direct-sowing into soil works and avoids transplant shock, but you’re staring at a pot for a week with no idea if anything’s alive — hard on the patience. Soaking in water until it sprouts is the one to avoid: that’s how I lost my first seed. The paper towel gives you visibility and reliability, which is exactly what you want the first few times. DIG stock proper propagation kits and heat mats if you want to take the guesswork out, but a glass, two plates and a warm spot will get you there.

FAQ

How long does it take a cannabis seed to germinate? Usually 24–72 hours to crack, though older or tougher seeds can take up to seven days. Don’t give up before a full week of no change.

How long should I soak cannabis seeds? 12–18 hours, no more. Beyond about a day the rot risk climbs sharply, which is the most common way beginners kill a seed before it starts.

Should the seed float or sink? Either can germinate. Sinking is a mild good sign, but plenty of floaters sprout fine — don’t bin a seed just because it floats.

When is the taproot ready to plant? When it’s about 0.5–1cm long. Plant it taproot-down about 1cm deep before it grows long enough to tangle and tear.