Short version: Sprout seeds in a damp paper towel kept warm (21–26°C) and dark until a taproot appears in 1–5 days, then plant it root-down about a centimeter deep. For the first couple of weeks keep seedlings warm, humid, gently lit, and barely watered — and hold off on nutrients. Overwatering is what kills most seedlings.
The first two weeks are the most fragile — and the most over-managed — part of a grow. Seedlings don't need much; they mostly need you to not do too much. Here's the whole early stage, start to transplant.
Germinating the seed
The paper-towel method is the most reliable and lets you confirm the seed popped before it goes in the medium:
- Dampen two paper towels so they're moist but not dripping, place the seeds between them, and put that between two plates (a dark, humid pocket).
- Keep it warm (21–26°C / 70–79°F) and dark. Check daily so the taproot doesn't grow into the towel.
- A taproot appears in 1–5 days. When it's about 0.5–1 cm long, plant it taproot pointing down, roughly 1 cm deep, and lightly cover.
You can also plant seeds directly in your final medium — less handling, slightly less certainty. Either way, keep the surface lightly moist until it breaks ground.
The first two to three weeks
Seedlings want a gentle, stable environment:
- Warmth & humidity: around 22–26°C and 65–70% humidity. A humidity dome for the first few days helps the tiny root system keep up.
- Light: gentle. Keep an LED dimmed or 24–36 inches (60–90 cm) away — seedlings bleach and "taco" under too much intensity. An 18/6 schedule is a safe default.
- Nutrients: none at first. The seed carries its own food. Start at quarter strength only once the plant has 3–4 sets of true leaves.
- Water: sparingly, in a ring a few inches from the stem, keeping the medium damp like a wrung-out sponge — never soaked. See how to water without drowning your plants.
The mistakes that kill seedlings
- Overwatering → "damping off," where the stem rots at the soil line. The #1 killer.
- Too much light or heat → bleached, curling ("tacoing") leaves.
- Nutrients too early or too hot a soil → burnt leaf tips.
- A fan blasting the seedling → whipping and stress. Keep airflow gentle and indirect.
Most first grows are lost in exactly this window — our weeks 3–5 survival guide covers what comes right after.
When to transplant
Move up a pot size once roots fill the starter (you'll see them at the drainage holes) and the plant has a few nodes. Transplant gently to avoid shocking the roots — or start seeds in their final pot to skip the step entirely. For feeding the young plant, our best nutrients for seedlings guide helps.
Frequently asked questions
How long do cannabis seeds take to germinate?
Most viable seeds pop a taproot within 1–5 days using the damp paper-towel method kept warm (21–26°C) and dark. Plant the seed root-down about a centimeter deep once the taproot is roughly half a centimeter long.
Do seedlings need nutrients?
Not at first — the seed provides everything for the first week or two, and feeding too early burns the delicate roots. Begin with quarter-strength nutrients only once the seedling has three to four sets of true leaves.
Why is my seedling drooping or falling over?
The most common causes are overwatering (which can rot the stem at the soil line, called damping off) and too much light or heat. Keep the medium just damp, move the light farther away or dim it, and keep airflow gentle.
