A Simple Countdown for Starting Seeds Indoors

Timeline counting down from eight weeks before the last frost to planting day, with seedlings growing larger

 

Starting seeds indoors is mostly a matter of timing. Plant too early and seedlings grow leggy and root-bound before the weather allows planting out. Plant too late and the crop loses weeks of its season. Counting backwards from your last spring frost date solves this.

The countdown

  • 8 to 10 weeks before: peppers and eggplant, which grow slowly and like warmth.
  • 6 to 8 weeks before: tomatoes, plus onions and leeks if you start them from seed.
  • 4 to 6 weeks before: broccoli, cabbage, cauliflower and kale for a spring crop.
  • 3 to 4 weeks before: lettuce, if you want an early head start.
  • 2 to 4 weeks before: cucumbers, squash and melons, which dislike root disturbance and grow fast.

These are typical ranges. Your seed packet is the best guide for a specific variety, so treat the list as a starting point.

What seedlings actually need

Use a light seed-starting mix, not garden soil. Keep it evenly damp like a wrung-out sponge. Once seedlings emerge, light matters more than anything else: a bright window helps, but a simple grow light a few inches above the leaves, run for most of the day, keeps stems short and sturdy.

Before they go outside

Spend about a week hardening seedlings off: an hour or two outdoors in shade on the first day, then longer and sunnier each day. This avoids the shock that stalls plants moved straight from the house.

To get an exact sow date for each crop from your own frost dates, use the free planting calendar, and see the starting seeds indoors guide for the full method.

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