My Seeds Are Not Germinating Indoors — What Is Going Wrong?

Waiting for seeds to appear and seeing nothing is one of the most frustrating experiences for a gardener. Before you give up and resow, it is worth working through the checklist of common causes. In the vast majority of cases, one of a handful of fixable problems is responsible — and most can be corrected without starting over.

The Compost Is Too Cold

This is the most common cause of failed germination, especially for tomatoes, peppers, and aubergines. Check the actual compost temperature with a soil thermometer — room air temperature and compost temperature can differ by 4–6 °C. A propagator or heat mat set to the correct range for your crop solves this immediately. A windowsill in February can have glass temperatures of 12–14 °C at night, which will stall or stop germination entirely.

The Compost Is Too Wet or Too Dry

Seeds need consistent moisture — not waterlogged, not drying out. If compost dried out in the first few days after sowing, the seed coat may have dried before the radicle could break through. Water from below, replace the propagator lid, and wait. If compost is waterlogged, seeds may have rotted — tip them out, examine them, and resow in fresh damp (not wet) compost.

Seeds Were Sown Too Deep

Very small seeds like celery, petunias, and lettuce must be sown on the surface or barely covered. If they were buried more than a few millimetres, the seedling may germinate and then exhaust its energy before reaching light. Resow at the correct depth.

The Seeds Are Old or Stored Badly

Seed viability declines with age and poor storage. Seeds stored in a warm, humid drawer for several years may have very low germination rates. Test viability by placing 10 seeds on a damp piece of kitchen paper, folding it over, and keeping it in a warm place for a week. If fewer than 5 of 10 germinate, sow thickly to compensate or buy fresh seed.

The Crop Simply Takes a Long Time

Some crops are naturally slow. Parsley routinely takes 3–4 weeks. Celery can take 3 weeks even in ideal conditions. Chillies and aubergines often take 2–3 weeks. Check the expected germination time for your specific crop before concluding there is a problem.

When to Resow

If two weeks have passed beyond the expected germination window and nothing has appeared, resow. Use fresh seed if possible, double-check your temperature, pre-moisten the compost before sowing, and confirm the sowing depth is correct for that crop.