Seedling
The first two weeks set the ceiling — give her a clean start, then get out of the way.
Everything from the seed you choose to how you germinate it decides how well the whole grow goes. Get the genetics, the moisture, and the patience right, and the plant does most of the work herself.
What good looks like
How the seedling stage unfolds
- 12-18 hrs
Soak
Seeds rest in a glass of room-temperature water for twelve to eighteen hours — long enough to soften the shell and wake the hormones inside. Floaters are fine; don’t read too much into them.
- Day 1-3
Taproot
On damp paper towel between two plates, kept dark and around 25°C, a small white taproot pushes out within 24-72 hours. Plant it once it’s half a centimetre to a centimetre long — don’t let it tangle.
- Day 3-5
Sprout breaks soil
A pale stem pushes through the surface, often still wearing the shell like a hat. That’s normal — the shell usually drops off on its own.
- Day 5-7
Cotyledons open
Two small round leaves spread out and feed the plant from the seed’s stored energy. They don’t look like cannabis leaves, and they’ll yellow and drop later — that’s fine.
- Day 7-14
First true leaves
The first real serrated leaves appear — a single finger, then three. She’s photosynthesising on her own now and building roots below the surface.
- Wk 3
Young plant
Growth speeds up, the stem thickens, and roots fill the small pot. Three or four sets of true leaves and a stem you can’t easily bend means she’s ready for the next stage.
Revision flashcards · tap to reveal
The numbers that matter — can you remember?
Before you start
What you'll need
Tick off what you've already got. Whatever's left, the kit just below has you sorted — skip anything you don't need.
Get your gear
Your Seedling kit
The exact bits I'd reach for at this stage — affiliate links, so they cost you nothing extra and help keep the lights on here.— Dave
Swipe right to add · left to skip · or use the buttons
Watch for
Catch these early
The early sign, what it means, and the fix. The full stories are in the book.
Tall, thin, leaning like it’s had a few pints.
The Stretch — the light is too far away or too weak, so she’s reaching and building a stem that can’t hold itself up.
Fix: Lower the light or raise the plant, and mound a little soil up around the base for support. She’ll thicken once she’s getting enough light.
📖 Dave’s seen the stretchy ones recover in a week — and the ones left too long fold under their own weight. The full story →
Drooping, soil dark and wet, the base of the stem thin and slightly translucent.
The Drown — overwatering tipping into damping off, a fungus that thrives in wet, still, warm air.
Fix: Prevention is the only cure: less water, more air, and a fan. By the time the stem goes soft at the base, it’s usually too late.
📖 The same drowning Dave gave his barbecue-bag seed in a glass — three days with no oxygen turned it to compost. The full story →
Leaves curling, yellowing, or bleaching closest to the light.
The Scorch — the light is sitting too close and burning the first leaves.
Fix: Move it up. For seedlings, 60-75cm is usually safe with an LED, and when in doubt further away beats closer.
📖 Unlike the stretch, scorch is the one they don’t come back from. The full story →
Cotyledons yellowed and dropped, first leaves pale, barely any growth in a week.
The Starvation — a very light seed-starting mix can run out of food before you start feeding.
Fix: Start a quarter-strength feed, nothing stronger. A pale seedling greens up in days on a gentle feed and burns on a full dose.
📖 Dave saw a customer pot a seedling into full-strength compost — a three-course meal for something that needed a glass of water. The full story →
Questions
Seedling FAQ
Feminised or autoflower for my first grow?
Either, as long as it says feminised — that one word means only female plants, which is what you want. Autos are faster and more forgiving (seed to harvest in 8-12 weeks) but give you less control over size; photoperiods let you decide when to flip. For a first grow, an auto’s trade-off is usually worth it.
How long should I soak my seeds?
Twelve to eighteen hours in room-temperature water, then onto damp paper towel. Not longer. Leaving a seed swimming for days starves it of oxygen and it rots — that’s exactly how a forgotten bag seed ends up grey and mushy.
My seed hasn’t cracked after three days — is it dead?
Probably not. Some seeds take up to seven days, especially older or harder-shelled ones. Only call it dead if it’s gone soft and mushy, or if it’s still completely unchanged after a full week.
When do I start feeding nutrients?
Not for the first two weeks. The seedling feeds itself from the cotyledons and whatever’s in the soil. Wait until the cotyledons start to yellow and the plant has two or three sets of true leaves, then start at quarter strength — not half, not full.
How do I know she’s ready for a bigger pot?
Look for three or four sets of true leaves (not counting the cotyledons), a stem you can’t easily bend with two fingers, and roots poking out the drainage holes. Leave her too long and the roots circle the pot and growth stalls — that’s rootbound, and it’s the next stage’s territory.
Revision · quiz
Can you remember the seedling numbers?
Five quick ones, straight from the flashcards above. Instant feedback, retry till it sticks — no marks, no pressure.
1. How long should you soak a seed in room-temperature water before moving it to paper towel?
Hours soften the shell and wake her up, but leave a seed swimming for days and you starve it of oxygen — it rots in the glass.
2. What temperature do you want for germinating the seed on the paper towel?
Warmth is the whole game here — too cold and she sulks, too hot and you cook her before she is even out of the shell.
3. What humidity suits a young seedling?
A seedling has barely any roots, so she drinks through her leaves — keep the air damp and you take the pressure off that tiny root system.
4. How high should an LED sit above a seedling?
Too close and you scorch the first leaves — and unlike the stretch, scorch is the one they do not come back from, so when in doubt go further away.
5. True or false: a healthy seedling should get a quarter-strength feed within its first few days.
Feed nothing for the first two weeks — she is still living off the seed, and rich compost is a three-course meal for something that only wanted a glass of water.
Go deeper
The lessons for this stage
Germination is waking the seed up. Three things make it happen: moisture, warmth, and darkness.
6 min read The First Three Weeks: What Normal Looks LikeYou can't spot a problem if you don't know what healthy looks like. That's the whole point of this lesson.
6 min read Watering and the Root ZoneRoots need air more than they need water. Not instead of — more than. In order of priority, roots want air, then water, then nutrients.
6 min read You Will Overwater (Everyone Does)You're going to overwater your plant. Everyone does.
5 min readThe whole story is in the book
The full germination stories — the drowned barbecue seed, the two-euro ten-pack that hermied a whole grow — and every scar Dave earned learning this are in Grow Good Bud.
The web gives you the lesson; Grow Good Bud keeps the scars. The kit to grow it is at Dublin Indoor Gardening.