Grow From Seeds

Common mistakes when growing seeds indoors

Nearly every failed tray traces back to a few causes: wrong timing, wrong mix, too wet, too cold, too dark, too crowded.

The ten mistakes

  1. Sowing too early. Seedlings outgrow their pots and get leggy long before it is safe to plant out. Clemson gives 6 to 8 weeks for tomatoes and 3 to 5 for squash and cucumbers; the planner works backwards from your frost date.
  2. Sowing too late, then having no time to harden off before the season.
  3. Using garden soil or old potting mix instead of a sterile seed mix (mixes).
  4. Sowing too deep or too shallow (depth).
  5. Overwatering, or letting it dry out (watering).
  6. Not enough light, giving tall, pale stems (light).
  7. Not enough warmth for germination (temperature).
  8. Overcrowding and no air movement, leading to damping off and mould (mould).
  9. Skipping hardening off (hardening off).
  10. Giving up too soon on slow seed (when to give up).

Work out your own problem

Two tools save guessing. The germination troubleshooter asks a few questions about seed that has not come up, and the seedling problem picker matches what you can see on seedlings that have.