Starting seeds indoors in zone 5, crop by crop
Short answer
In zone 5, seed starting runs from early February to early May. Onions, leeks, peppers and celery go first in February, tomatoes and broccoli in March, and fast growers like squash, cucumbers and melons in April. Everything is counted back from a last frost around April 30.
In zone 5, most seed starting happens between early February and early May. The slow growers go first, as much as 12 weeks before the last frost, and the quick ones go last, just a few weeks ahead.
Zone 5’s average last frost is around April 30. Every date here is counted back from that, which is why seed packets say “6 to 8 weeks before last frost” rather than naming a month.
The zone 5 seed starting chart
| Crop | Sow indoors | Plant out |
|---|---|---|
| Onions | Early February to early March | Mid-March to late April |
| Leeks | Early February to mid-March | Mid-April to early July |
| Celery | Mid-February to mid-March | Mid-May to mid-June |
| Peppers | Mid-February to mid-March | Mid-May to mid-June |
| Eggplant | Mid-February to mid-March | Late May to mid-June |
| Parsley | Mid-February to early April | Early April to late May |
| Cabbage | Mid-February onwards | From early April |
| Tomatoes | Early March to early April | Mid-May to mid-June |
| Broccoli and kale | Early March onwards | From early April |
| Lettuce | Early March to mid-April | From early April |
| Basil | Mid-March to mid-May | Mid-May to late June |
| Cucumbers, zucchini, squash | Early April to early May | Mid-May to early June |
| Melons | Early April to late April | Late May to mid-June |
Two groups stand out. The hardy crops (onions, leeks, cabbage, broccoli, kale, lettuce and parsley) can go out in April, before the last frost, because a light frost won’t hurt hardened-off plants. The tender ones (tomatoes, peppers, eggplant, basil, squash, cucumbers and melons) wait until mid-May, when frost is unlikely and the soil has warmed.
Zones are mapped from winter lows, not frost dates, so treat this chart as a starting point. If your own last frost is usually mid-May, shift every date two weeks later. VegLog works these dates out from your own town’s frost dates if you’d rather not do the arithmetic.
What you need
- Seed-starting mix, not garden soil. It’s fine, light and free of weed seeds.
- Containers with drainage: cell trays, small pots or soil blocks.
- Light. A south window is rarely enough before April. An LED shop light 2 to 3 inches above the seedlings, on for 14 to 16 hours a day, stops them stretching. Raise it as they grow.
- Warmth to germinate. Peppers, eggplant and tomatoes come up much faster at 75 to 85 °F. A heat mat under the tray does the job. Take it away once seedlings are up.
Sowing and growing on
- Moisten the mix before filling the trays.
- Sow two seeds per cell at the depth on the packet, about twice the seed’s width. Tomato and pepper seed goes a quarter inch deep.
- Cover with a clear lid or plastic to hold in moisture until the seedlings appear, then remove it.
- Thin to the strongest seedling in each cell by snipping the other.
- Water from below when the surface starts to dry. Constantly wet mix encourages damping off.
- Move tomatoes, peppers and eggplant into 3- or 4-inch pots once they have their first true leaves.
Hardening off
Indoor seedlings have never felt wind, full sun or a cold night. Give them a week to adjust before planting out. Start with an hour or two in a sheltered, shady spot, and leave them out a little longer each day, with more sun each time. By the end of the week they can stay out overnight, as long as frost isn’t forecast for tender crops.
Common mistakes
Starting too early. The most common one. A tomato sown in January will be leggy and root-bound by May. Squash and cucumbers sown in March are worse. Stick to the dates.
Too little light. Pale, tall, floppy seedlings are reaching for light. Move the light closer.
Damping off. Seedlings that collapse at soil level. Use fresh mix, clean trays, water from below and keep air moving with a small fan.
For planting the tomatoes you’ve raised, see tomatoes in zone 5.
Questions people also ask
How many weeks before the last frost should I start seeds?
It depends on the crop. In zone 5, onions and peppers go in about 8 to 12 weeks before the last frost, tomatoes 4 to 8, and squash, cucumbers and melons only a few weeks ahead. Starting fast growers too early gives leggy, pot-bound plants.
Do I need grow lights to start seeds?
Not strictly, but it helps a lot. Even a south window in February and March is too dim for most seedlings, which stretch toward the glass. A simple LED shop light a few inches above the trays makes sturdier plants.
What can I sow directly outside instead?
Peas, spinach, radishes, carrots, beets and lettuce can all be sown straight into the garden in spring. Beans and sweet corn are usually sown outside once the soil warms in mid to late May.
Dates set to your own frost dates
VegLog works out sowing and planting times for your town, then reminds you when each job is due.
