March is when Zone 7 wakes up properly. The average last frost falls between Mar 15 and Apr 1, so by late March the garden opens for tender crops — and the month is a rush of transplanting, sowing and first harvests. It is the busiest month of the Zone 7 year, and the one where a little patience pays off more than a lot of enthusiasm.
What March means in Zone 7
Zone 7 is a generous gardening zone: average annual minimum temperatures of 0 to 10°F mean winters are cold but rarely brutal, and the frost-free season stretches long enough for two full rounds of many crops. The frost-free season lasts about seven months, from late March into early November. The average last spring frost falls in the Mar 15–Apr 1 range and the average first autumn frost in the Nov 1–15 range — USDA zone averages, not exact dates, so check your local extension service before planting tender crops outside. Our planting calendar by ZIP turns them into a month-by-month plan.
Zone 7's frost-free season starts in late March, so March is the bridge month: indoor seedlings grow on, hardy crops go out early, and tender crops follow once the frost risk has passed. Peas, spinach, lettuce, carrots and radishes can all be sown outdoors in March, brassica seedlings can be transplanted out, and by the end of the month tomatoes and peppers can go out in the mildest spots — but a frost in the last week of March is still entirely possible, so keep the frost cloth handy.
March task list
- Direct-sow peas, spinach, lettuce, radishes, carrots and beets. 2. Transplant brassicas, onions and leeks; harden them off first. 3. Start squash, cucumbers and basil indoors in late March. 4. Prepare beds: fork in compost, rake level, and mulch paths. 5. Set up trellises and pea supports before plants need them. 6. Watch for slugs on young seedlings after rain.
What to start indoors now
Start squash, cucumbers and zucchini indoors in late March — they grow fast and should only spend 3–4 weeks inside, or they become root-bound and sulky. Start basil indoors now, and start a second round of lettuce indoors for transplanting into the garden. Keep growing on the tomatoes, peppers and brassicas started in February, potting them up into larger pots when roots fill their containers. Use clean pots and fresh seed-starting mix, give seedlings strong light, and keep the soil moist but never waterlogged. Work out exact sowing dates with the seed-starting calculator.
What to direct-sow outdoors
Direct sow peas (60–70 days), spinach (40–50 days), lettuce (45–60 days), radishes (25–40 days), carrots (60–80 days) and beets (50–70 days) outdoors in March, once the soil can be worked. Sow scallions and parsnips (100–130 days) too — parsnips are slow to germinate (14–28 days), so mark the row and be patient. Sow a first round of cilantro and dill in a sheltered spot, and sow green beans in late March only in the warmest, most sheltered parts of the zone. Prepare the bed first — fork it over, remove weeds, rake it level — then sow thinly, water gently, and thin seedlings to the spacing in the table below.
What to transplant now
Transplant broccoli, cauliflower and cabbage seedlings outdoors in March, spacing them 18–24 inches apart, and protect them with row cover if a frost is forecast — they are frost-tolerant, not frost-proof. Transplant onion and leek seedlings started in January, setting them out in rows 4–6 inches apart. From late March, once the last frost range is passing, harden off tomato and pepper seedlings and transplant them out in the mildest spots — but keep frost cloth ready. Harden seedlings off for a week first, plant on a cloudy day or in the evening, water them in well, and mulch around — but not against — the stems.
What to harvest this month
March harvests are the first fresh food of the year: overwintered leeks, parsnips and Brussels sprouts, plus lettuce and spinach from the cold frame. Cut the first spring herbs — chives and mint are usually up by late March. Early peas sown in February may be flowering by the end of the month. Indoors, microgreens and windowsill herbs keep producing while the outdoor garden gets going. Harvest in the morning, when plants are cool and crisp, and pick little and often — regular picking keeps most vegetables producing.
Frost protection in Zone 7
March frost is the trap of the Zone 7 year: the average last frost is Mar 15–Apr 1, and a warm March week tempts gardeners to plant tender crops weeks early — then a cold night kills them. Keep frost cloth handy for the brassicas, peas and any early tomatoes, and do not be fooled by one warm weekend. Soil temperature matters as much as air temperature: peas and spinach germinate in cool soil, but beans and corn rot in it, so wait for real warmth before sowing tender seeds. When a cold night is forecast, water the soil in the afternoon, cover tender plants with frost cloth before sunset, and remove the covers in the morning. The Seed-Starting Calculator can help you time plantings around your frost dates.
Planting data for March in Zone 7
All figures below are broad published ranges from standard horticultural references, not exact figures — they vary by variety, climate and soil.
| Crop | Action this month | Days to maturity | Notes |
|---|---|---|---|
| Peas | Direct sow | 60–70 | Sow once soil can be worked |
| Carrots | Direct sow | 60–80 | Slow to germinate (14–21 days) |
| Radishes | Direct sow | 25–40 | Fastest spring crop |
| Broccoli | Transplant outdoors | 60–85 | Space 18–24 in; row cover if frost threatens |
| Tomatoes | Transplant (late Mar, mild spots) | 60–85 | Harden off first; keep frost cloth ready |
| Zucchini | Start indoors (late Mar) | 45–55 | Only 3–4 weeks indoors |
Browse the full planting calendar hub for every Zone 7 month, and see the neighbouring months in this zone:
Frequently asked questions
What can I plant in March in Zone 7?
Peas, spinach, lettuce, radishes, carrots, beets, scallions and parsnips outdoors, plus brassicas, onions and leeks as transplants. Tomatoes and peppers can go out in late March in the mildest spots, with frost cloth ready.
Can I plant tomatoes outside in March in Zone 7?
In late March, in the mildest parts of the zone, after hardening off — but only with frost cloth ready. The average last frost is Mar 15–Apr 1, so early April is safer for most Zone 7 gardens.
When is the last frost in Zone 7?
The average last spring frost falls between Mar 15 and Apr 1. These are USDA zone averages, not exact dates — check your local extension service and the forecast, and keep frost cloth handy through April.
How do I stop slugs eating my seedlings?
Go out at dusk with a torch and pick them off, keep mulch away from young stems, and water in the morning so the soil surface dries by night. Beer traps and copper tape help in small beds.