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Germination troubleshooter
Start with the check: is your seed actually late, or just slow? Then pick the symptom.
1. Check your sowing against the data
Enter your details.
2. What does it look like?
Nothing has come up
- Not long enough yet. Check the typical days to germinate for the plant. Parsley, onions, peppers and many perennials take two to four weeks or more.
- Too cold (or too hot). Compare the soil temperature, not the air, with the germination range. Cold soil makes seed sit and rot; heat can stop lettuce and spinach. A heat mat solves cold; shade and cool mix solve heat.
- Sown too deep, or covered when it needs light. Tiny seed and light-needing seed belong on the surface. Large seed buried deeply runs out of energy. Check depth and light on the plant page.
- Dormant seed. Many perennials, wildflowers, trees and some herbs need cold-moist stratification, a soak or scarification before they will germinate. See the plant page and the seed-starting guide.
- Dried out or waterlogged. The mix must stay evenly damp from sowing to emergence. A dome or film helps; soggy mix rots seed.
- Old or badly stored seed. Viability falls with age and with heat and damp. Test: wrap ten seeds in a damp paper towel in a bag, keep warm and count germinators.
Seedlings collapse at the soil line
- Damping off. A fungal disease that pinches the stem at the base of young seedlings in cold, wet, crowded conditions. There is no cure once it starts: remove affected seedlings, let the surface dry, increase air flow and sow thinner.
- Prevention. Clean trays, fresh seed-starting mix, water from below, remove the dome after emergence, keep warm enough for the crop and do not overcrowd.
Tall, pale, floppy seedlings
- Not enough light. The most common cause. Put grow lights a few inches above the seedlings for about 14 to 16 hours a day; windowsills in winter are rarely enough.
- Too warm after germination. Once up, most seedlings do better cooler than they germinated.
- Fix. Brush or fan them daily to strengthen stems; bury tomato stems deeper when potting up.
Yellow leaves
- Cold or soggy mix. Roots cannot take up nutrients in cold, wet mix. Let the surface dry and warm the mix.
- Hunger. Pale lower leaves after the seed leaves fade point to nitrogen shortage; give a dilute organic liquid feed.
- Old seed leaves. Seed leaves yellowing and dropping after true leaves appear is normal.
Purple tinge on leaves
- Cold roots. Often shown by tomatoes and peppers in a cold room; phosphorus is locked up in cold mix. Warm the roots and it usually passes.
Wilting seedlings
- Too dry or too wet. Check the mix: dry means water from below, wet means let it dry and improve drainage.
- Damping off or stem rot. If the stem is thin and dark at the base, see damping off.
- Transplant shock. Harden off gradually and water in after moving.
Mould, algae or fungus gnats
- Surface mould or green film. Too wet and too little air. Remove the dome, let the surface dry, and scrape off the top layer.
- Fungus gnats. Small flies breeding in constantly damp mix. Let the surface dry between waterings and use yellow sticky traps.
Patchy or uneven germination
- Uneven moisture or temperature. Edges of trays dry first; cold spots delay seed. Rotate trays and keep moisture even.
- Mixed seed lots. Seed from different years or sources germinates at different rates. Sow a little thicker and thin.
Seedlings are alive but not growing
- Cold, dark or hungry. Check temperature and light first, then feed lightly.
- Root-bound or too small a pot. Pot up when roots fill the cell.
- Seed-coat stuck on the leaves. Mist to soften it; do not pull it off.
Plants flower or bolt too early
- Cold snaps or stress when young. Onions, leeks and many brassicas bolt after a cold spell when small; lettuce, spinach and cilantro bolt in heat and long days. Sow at the recommended time and choose bolt-resistant varieties.
Seedlings eaten
- Slugs, birds, mice, cutworms. Cover with mesh or fleece, collar seedlings, keep trays off the ground and check at dusk. Mice dig up bean and pea seed: sow in cells and transplant.
Still stuck? The plant page lists the problems specific to each crop, and Grow From Seeds covers technique for beginners.