If your seeds are not germinating, the cause is almost always one of four things: the seed is old or dead, the soil is too cold or too hot, the soil is too wet or too dry, or the seeds were planted too deep. Work through the checks below in order — the first test takes ten minutes and tells you whether the seed itself is still alive.
First, Run the 10-Minute Viability Test
Before changing anything else, find out if your seeds can sprout at all.
- Count out 10 seeds from the packet.
- Lay them on a damp paper towel, fold it over, and seal it in a zip bag.
- Keep it warm (70–75°F / 21–24°C) and check from day 3.
- After the crop’s normal germination time, count how many sprouted. 8–10 = fresh seed, sow normally. 5–7 = usable, sow thicker. Under 5 = the packet is the problem, not you — replace it.
If the test seeds sprout on the towel but not in soil, the problem is your soil conditions — temperature, moisture or depth — and the causes below will pinpoint it.
Cause 1: The Seed Is Too Old
Seed does not last forever. Onion and parsnip seed can lose viability in a year; tomato and pepper seed often stays good for 4+ years. Packets stored in a hot garage or humid shed age much faster than seed kept cool, dry and dark.
Fix: Run the viability test. Store seed in a sealed jar with the packet, in a cool dark place.
Cause 2: Soil Too Cold
Most warm-season seeds simply wait — or rot — in cold soil. Peppers sown into 60°F soil can sit for three weeks. Nothing is “wrong”; the seed is waiting for warmth it may never get indoors on a cold windowsill.
Fix: Move trays somewhere warmer, or use a heat mat. Check our seed germination temperature chart for the exact range your crop wants.
Cause 3: Soil Too Hot
The forgotten opposite. Lettuce, spinach and celery refuse to germinate in hot soil — lettuce becomes dormant above about 75°F. Summer sowings on a hot patio fail for this reason.
Fix: Sow in the evening, shade the tray, or wait for a cooler spell. Start heat-sensitive crops indoors where you control the temperature.
Cause 4: Too Much Water
The most common killer. Soaking-wet mix contains almost no oxygen, and seeds need oxygen as much as water. The seed swells, then rots — dig one up and a soft, dark, mushy seed confirms it.
Fix: The mix should feel like a wrung-out sponge. Water, let it drain fully, and never leave trays standing in water.
Cause 5: Too Little Water, or Water That Comes and Goes
A seed that starts germinating and then dries out dies mid-process — it cannot pause and restart. Surface soil dries fastest, which is why shallow-sown seed fails first.
Fix: Keep moisture constant until seedlings are up. A clear cover or lid holds humidity; check daily rather than watering on a schedule.
Cause 6: Planted Too Deep
A seed contains only enough stored food to push its shoot a short distance. Planted too deep, it runs out of energy before reaching light. The rule: sow about twice as deep as the seed is wide. Tiny seeds belong on or just under the surface.
Fix: If nothing appears and conditions were otherwise good, carefully scratch the surface — seeds germinating below with pale, exhausted shoots confirm depth was the problem. Re-sow shallower.
Cause 7: Planted Too Shallow
The mirror problem: seeds on the surface dry out between waterings or get washed out of place by a heavy watering can.
Fix: Press surface-sown seeds firmly into the mix so they have full contact with moist soil, and water with a spray, not a stream.
Cause 8: The Seeds Need Light — or Darkness
Most seeds are indifferent, but a few are not. Lettuce, celery and many small herbs germinate better with light. Some large seeds do better covered and dark. Planting a light-needing seed an inch deep guarantees failure.
Fix: Check the packet. If it says “sow on surface” or “needs light”, obey it exactly.
Cause 9: Hard Seed Coats and Dormancy
Some seeds are built to wait: sweet peas, okra, nasturtium and many perennials have hard coats or built-in dormancy. In nature, winter cold (stratification) or passing through an animal breaks that wait; in a seed tray, nothing does.
Fix: Soak hard seeds 8–12 hours before sowing, or nick the coat gently (scarification). Perennial seed often needs weeks of cold, moist conditions in the fridge first.
Cause 10: Pests and Disease Got There First
Fungus gnats, ants and mice all eat sown seed, and damping-off fungi kill seedlings just below the surface — you will find a sprout toppled with a pinched, brown stem base.
Fix: Use fresh sterile seed mix (not garden soil), cover trays, and add airflow. Our step-by-step guide on how to germinate seeds covers a clean setup that prevents most of this.
Cause 11: You Just Need to Wait Longer
Parsley takes 2–3 weeks. Peppers can take 2 weeks even in good conditions. Many “failures” are trays thrown out on day 8. Check the realistic range for your crop before you give up — and judge by soil temperature, not by the calendar.
Quick Diagnosis Table
| What you find | Most likely cause |
|---|---|
| Seeds unchanged, firm, after 2 weeks | Too cold, or dormant/hard coat |
| Seeds soft, dark, mushy | Too much water |
| Seeds sprouted in test, not in soil | Temperature, depth or moisture in soil |
| Sprouts pale and floppy | Too little light after sprouting |
| Sprouts collapsed at soil line | Damping off |
| Nothing at all, packet 2+ years old | Dead seed — replace |
Frequently Asked Questions
How long should I wait before giving up on seeds? Wait at least the crop’s maximum normal germination time at your soil temperature, plus a few days. Cold soil doubles many times. Run the paper towel test in parallel — it tells you quickly whether to keep waiting.
Can old seeds be revived? No. Once a seed is dead, nothing revives it. The viability test tells you what percentage is still alive so you can sow thicker or replace the packet.
Why do seeds germinate in the packet test but not in my garden? Outdoor soil is colder, dries faster and varies more than a paper towel. Depth and moisture outdoors are the usual culprits, in that order.
Does the moon phase or sowing calendar matter? There is no reliable evidence that lunar sowing changes germination. Temperature, moisture, depth and seed age explain virtually all real-world results.
Should I dig up seeds to check them? One or two, carefully, yes — after the expected time has passed. A firm pale seed is alive and waiting; a soft dark one has rotted. Disturb as few as possible.
