When to start seeds in the NC Piedmont: a seed-starting calendar for zone 7b
By FarmerTested · a network of working growers based in Waxhaw, NC
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Every winter, somebody at the market asks me when they should start their tomatoes. The honest answer is "it depends on your frost date," which isn't very satisfying when you're standing there with a seed packet. So here's the longer answer, written for the southern Piedmont of North Carolina, where I farm, and for anywhere else that sits around USDA zone 7b.
The short version: January is for onions, leeks and slow herbs. February is for peppers, eggplant, cabbage-family crops and lettuce. Tomatoes go in late February or early March. Squash, cucumbers and melons wait until spring, or go straight into the ground.
Start with your last frost date, not the calendar
Every seed-starting schedule worth using counts backward from your average last spring frost. That date moves a lot across the state, and even across a county. Low spots and river bottoms frost later than hilltops a mile away.
For much of the Piedmont, the average last freeze lands somewhere in early to mid April. Don't take my word for your yard, though. NC State Extension keeps a table of average first and last freeze dates by weather station, so find the station closest to you. If you're outside North Carolina, your state's extension service will have the same thing.
Keep in mind that an average last frost means a frost after that date is still possible in plenty of years. I treat it as a planning date, then watch the 10-day forecast before anything tender goes out.
The example calendar (last frost: April 10)
To make the math concrete, the table below uses April 10, 2027 as an example last-frost date. It's an example, not a forecast. If your date is a week later, push every row back a week.
| Crop | Sow indoors | Example sow date | Goes outside |
|---|---|---|---|
| Onions and leeks (from seed) | 10–12 weeks before last frost | Jan 16 – Jan 30 | Hardy. Set out in March while it's still cool. |
| Parsley, thyme, oregano | 8–10 weeks before | Jan 30 – Feb 13 | Parsley takes light frost. Others go out around the frost date. |
| Peppers and eggplant | 8–10 weeks before | Jan 30 – Feb 13 | 1–3 weeks after last frost, once soil is warm |
| Broccoli, cabbage, kale, collards | 6–8 weeks before transplanting | Late Jan – early Feb | 3–4 weeks before last frost (mid March) |
| Lettuce and other salad greens | 4–6 weeks before transplanting | Feb 13 – Feb 27 | Late March. Cover it if a hard freeze is coming. |
| Tomatoes | 6–8 weeks before | Feb 13 – Feb 27 | After last frost |
| Basil | 4–6 weeks before | Feb 27 – Mar 13 | Well after last frost. Basil hates cold nights. |
| Squash, cucumbers, melons | 2–3 weeks before, or direct sow | Mar 20 – Mar 27 | After last frost. They don't like their roots disturbed. |
Weeks-before-frost ranges are the standard rules of thumb printed on most seed packets and in extension guides. For the dates to plant outside in central NC, check NC State's Central North Carolina planting calendar. Peregrine Farm's estimated planting dates for the NC Piedmont, published by NC State's Growing Small Farms, are a good farmer's cross-check.
Why I lean toward the later end of each window
The most common seed-starting mistake I see isn't starting too late. It's starting too early. A tomato sown in mid January in the Piedmont spends weeks waiting indoors for the ground to warm up. It gets tall, root-bound and hungry, and a stretched, stressed transplant often sits and sulks after it goes out. A stocky plant sown later can catch up and pass it.
If you're unsure, start a few seeds at the early end of the window and the rest two weeks later. You'll learn more from that one comparison than from any chart, including this one.
What to do each month
January
- Order seed early. Popular varieties sell out by late winter.
- Take stock of trays, mix and lights, and test your old seed. Roll 10 seeds in a damp paper towel, keep it warm, and count how many sprout.
- Sow onions and leeks mid-to-late month. They're slow and look like grass for weeks. That's normal.
February
- Early February: peppers, eggplant and the cabbage family. Peppers germinate slowly and like warm soil, which is where a heat mat earns its keep.
- Mid February: lettuce, the first tomatoes, and parsley if you haven't started it.
- Pot up anything that's outgrowing its cell, and start feeding once seedlings have true leaves.
March
- Harden off the cool-season crops for 7–10 days. Give them a few hours outside in the shade at first, then longer, then full sun. Plant them out mid-month.
- Late March: basil, plus a backup sowing of tomatoes in case a late cold snap gets the first batch.
April
- Harden off the warm-season crops. Plant them out after your frost date, once nights are reliably mild. Peppers in particular sulk in cold soil.
Hardening off is not optional
Seedlings raised under lights have never felt wind, full sun or a cold night. If you put them straight outside, the sun can scorch the leaves in an afternoon. The week of gradual exposure is the step people skip most often, and it costs them the most plants. Set a reminder for it the day you sow.
Where indoor towers fit
If you grow greens in an indoor hydroponic or aeroponic system, the frost date doesn't matter for those plants. Lettuce under lights in your kitchen doesn't care that it's January. That's a big part of why these systems appeal to people, and it's exactly what I want to find out for myself. I don't own one yet. When I buy my first test system this winter, I'll start the same lettuce varieties in the tower and in my usual trays and post how they compare. Starting seed for a tower is a little different from starting seed for soil, so I wrote a separate guide on rockwool, plugs and sponges.
What you'll need
You don't need much: trays, a soilless seed-starting mix, a light, and for peppers a heat mat. I broke down what a basic setup really costs, and how to set up a grow light so your seedlings don't stretch.
One place to order the varieties above is True Leaf Market's vegetable garden seed. Botanical Interests vegetable seeds is another packet-friendly option. More seed sources will go here as those programs approve us.
Follow along
I'll be starting my own trays this winter on this same schedule. I'll post what I sow and when in the newsletter, so you can sow alongside me and see how it goes, including what goes wrong.