When to start seeds indoors
Your seed-starting calendar, counted back from your last spring frost: when to sow each crop under lights, when to harden it off, and when it goes into the garden.
Typical last spring frost Apr 13 · first fall frost Oct 27. Adjust
Seed starting at a glance
A simple seed-starting routine
- Use fresh seed-starting mix, not garden soil; it drains well and carries fewer damping-off fungi.
- Sow at two to three times the seed's width and keep the mix evenly moist. A clear lid holds humidity until sprouts appear.
- Warmth to sprout, light to grow. Peppers and eggplant germinate fastest at 75–85°F soil; a heat mat helps. As soon as they sprout, give them bright light.
- Pot up into bigger cells once the first true leaves appear.
- Harden off for 7–10 days before the transplant date shown above.
Questions gardeners ask
When should I start seeds indoors?
Count back from your last spring frost. Onions, leeks and parsley need about 10 weeks; peppers and eggplant 8–9; tomatoes 6–8; brassicas 6–7; cucumbers, squash and melons only 3–4. The table on this page does the counting for your zone.
Can I start seeds too early?
Yes. Seedlings kept indoors too long become leggy and root-bound, and often transplant worse than younger plants. Starting on time beats starting early.
Which vegetables should not be started indoors?
Root crops such as carrots, beets, parsnips and radishes resent transplanting, and beans, peas and corn grow so fast from direct sowing that there is little to gain. Sow those straight into the bed.
Do seedlings need grow lights?
A sunny windowsill is rarely bright enough in late winter; seedlings stretch toward the glass. A basic LED shop light hung a few inches above the plants for 14–16 hours a day gives stocky seedlings.
What is hardening off?
Gradually getting indoor seedlings used to sun, wind and cool nights over 7–10 days before transplanting: an hour or two outside at first, building to a full day and night.