What to plant in March

March is the best month for direct-sowing cool-season vegetables outdoors in zones 6–8, for transplanting warm-season crops in zones 9–10, and for starting warm-season seedlings indoors in zones 5–7. The key mistake is rushing warm-season crops (tomatoes, peppers, squash) outdoor

March is when gardening begins in earnest for most of the country. Cool-season vegetables go directly in the ground from New England to the Pacific Northwest, warm-season transplants are moving outdoors in the South, and the indoor seed-starting calendar is at peak activity.

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What to direct sow outdoors in March

Peas — the classic March sow

Per Penn State Extension, "peas are one of the earliest vegetables that can be planted in spring." In zones 6–7, the traditional guidance is to plant peas on St. Patrick's Day (March 17) or as soon as the soil can be worked. Soil temperatures only need to reach 40°F for pea germination, though 55–65°F produces the fastest, most reliable germination.

Varieties matter for timing. Bush peas (snap and shelling types, 18–24 inches) work fine for direct sowing. Tall climbing types (up to 6 feet) need a trellis installed before planting.

In my zone 7a Long Island beds, I target the first week of March for pea sowing. Some years the soil is still frozen solid; other years it's workable. When the soil is workable but cold, a single layer of Agribon row cover row cover over the planting area warms the soil 4–6°F and improves germination timing.

Spinach, lettuce, arugula, mâche

Per Cornell Cooperative Extension, these cool-season leafy greens should be direct-sown "as soon as the soil can be worked in spring" for zones 5–7. March is the right window.

• Spinach: Germinates at 35–75°F. Direct sow 1/2 inch deep. Per Penn State Extension, "plant as early as 4–6 weeks before last frost."
• Lettuce: Germinates at 40–80°F; best at 60–65°F. Broadcast sow or drill sow 1/4 inch deep. Per NC State Extension, sow every 2 weeks for continuous harvest.
• Arugula: Germinates quickly (5–7 days) even in cold soil. Direct sow 1/4 inch deep. Very cold-hardy.
• Mâche (corn salad): Germinates at cold temperatures (40°F). Direct sow broadcast style.

Radishes

Per Penn State Extension, radishes "mature in 25–30 days" and are the fastest cool-season crop to reward March planting. Direct sow 1/2 inch deep, 1 inch apart. Thin to 2 inches when seedlings emerge.

Kale, collards, Swiss chard

These cold-hardy brassicas can be direct-sown in zones 6–8 in March. Per NC State Extension, "direct-sow kale 4–6 weeks before last frost." Swiss chard tolerates some frost and can be sown as early as mid-March in zone 6.

Beets and carrots

Beet seeds germinate at 50°F soil temperature. Per Penn State Extension, "plant beets 4–6 weeks before last frost." Sow 1/2 inch deep.

Carrots require at least 50°F for germination and benefit from more consistent warmth. In zone 6–7, late March direct sowings of carrot seed are appropriate. Carrots germinate slowly (10–21 days) — mark the row carefully and keep the soil surface moist.

Onion sets and transplants

Onion sets (small dormant bulbs) can be planted outdoors in March in zones 5–7. Per Penn State Extension, "onion sets may be planted as soon as the ground can be worked." Plant 1 inch deep, 4 inches apart.

Onion transplants grown indoors since January are ready for outdoor planting when they have pencil-thick stems. Harden off over 7–10 days before transplanting.

Potatoes

In zone 6–8, potato seed pieces can go in the ground in mid-to-late March. Per Penn State Extension, "plant when soil temperature reaches 45–50°F." Cut seed pieces to 1.5–2 ounces, with at least one eye each. Let cut surfaces cure 24–48 hours before planting. Plant 4 inches deep, 12 inches apart.

What to start indoors in March

Basil (zones 5–7)

Per Penn State Extension, start basil indoors 4–6 weeks before last frost. For zone 7 (last frost April 1–15), start basil in mid-to-late February to early March. For zone 6 (last frost April 15–30), start in early March. Basil seeds germinate quickly (5–7 days) at 70°F.

Cucumbers and squash — later in March

Per University of Minnesota Extension, cucumbers should be started "2–3 weeks before transplanting outdoors." For zone 6 (last frost April 25–May 1), starting cucumbers in late March gives a late-April transplanting opportunity, assuming cold protection is available.

Caution: Cucumbers and squash dislike root disturbance. Start in individual peat pots or soil blocks that transplant directly into the garden. Per Penn State Extension, transplanting from plastic cells often causes setback.

Marigolds and zinnias

Start marigolds indoors 4–6 weeks before last frost. For zone 7 (last frost April 15), start marigolds in early-to-mid March. For zone 5–6, mid-to-late March.

Zinnias grow so fast that 4-week-old transplants are usually better than 6-week-old ones. Start mid-to-late March for most zones 5–7.

Annual herbs for summer gardens

• Cilantro: Direct sow outdoors as soon as soil is workable (prefers cool conditions, bolts in heat)
• Dill: Direct sow outdoors when soil temperatures are above 45°F — dislikes transplanting
• Chives: If you didn't start chives indoors in January–February, March is a good time to divide existing clumps

What to transplant outdoors in March

Zone 8–9: warm-season transplants

In zone 8 (Atlanta, Charlotte, Dallas), tomato and pepper transplants can go outdoors in March with frost protection available. Per Clemson HGIC, "last frost in zone 8 averages March 15–30." Transplanting a few weeks before that date, with row cover or frost cloth, is common practice.

In zone 9 (Houston, Gulf Coast), tomato transplants that went out in late February are already growing. Start second successions and summer squash in March.

Zones 6–7: cool-season transplants

Broccoli, cabbage, and cauliflower transplants started indoors in January can go outdoors in March in zones 6–7 when nighttime temperatures stay above 28°F. Per Penn State Extension, broccoli transplants "tolerate frost to 26°F" once hardened off.

Ornamental tasks in March

Perennial garden cleanup

March is the right time for cutting back dead perennial stems left standing over winter. Per Penn State Extension, leave the cutting back until you see new growth emerging at the base of the plant — the dead stems protect the crown through winter. Once you see green growth emerging, the cleanup is safe.

Spring bulb beds

Leave daffodil, tulip, and other spring bulb foliage completely alone. Per Missouri Botanical Garden, "do not cut, braid, or remove foliage until it has yellowed naturally." The green foliage is replenishing the bulb for next year's bloom. My daffodil foliage typically doesn't come down until late May or June in zone 7.

Fertilizing overwintered plants

March is an appropriate time to apply a slow-release fertilizer to established perennials, shrubs, and trees as they emerge from dormancy. Per Penn State Extension, apply fertilizer when growth is just beginning, not before — applying to fully dormant plants wastes fertilizer that leaches before roots are active.

Regional guide for March

Northeast (zones 5–7)

Direct sow peas, spinach, lettuce, kale in zone 6–7 as soon as soil is workable (typically late February–March in zone 7, mid-to-late March in zone 6). Plant onion sets. Start basil, marigolds, and late tomato seedlings (zone 5) indoors.

Southeast (zones 7–9)

Zone 8: transplant warm-season crops with frost protection. Direct sow cool-season crops throughout March. Zone 9: full warm-season planting underway.

Midwest (zones 4–6)

Start onions, peppers, and tomatoes indoors. Zone 6b: plant peas outdoors by late March. Zone 4–5: no outdoor planting yet.

Pacific Northwest (zones 7–9)

Zone 8 (Willamette Valley, coastal zones): Plant peas, spinach, brassicas, and root crops directly in the garden throughout March. Per Oregon State Extension, "March is the primary cool-season planting month" for the Pacific Northwest.

West / California (zones 8–11)

Zone 9 Northern California: Start warm-season transplants; continue cool-season planting. Zone 10–11 Southern California: March is hot-season transition month. Plant tomatoes, peppers, and squash by early March.

State planting calendars

• New York: /planting/ny/
• New Jersey: /planting/nj/
• Pennsylvania: /planting/pa/
• Texas: /planting/tx/
• California: /planting/ca/

Common mistakes

Frequently asked

Can I plant tomatoes outdoors in zone 7 in March?

No. Zone 7 last frost averages April 1–15. Tomatoes are killed by frost and damaged by temperatures below 50°F. The earliest safe outdoor planting date in zone 7 is mid-April with row cover protection, or May 1 without. Per Penn State Extension, "cool soil temperatures below 60°F cause tomato plants to stall and develop purple leaves even without frost damage."

What's the difference between planting by air temperature and soil temperature?

Most gardening advice cites last frost date (an air temperature event). But soil temperature matters separately for germination and root development. Per NC State Extension, carrot seeds don't germinate well below 50°F soil; beans don't sprout below 60°F. An inexpensive a soil thermometer ($8–12) is one of the most useful tools for accurate spring planting timing.

Should I use a cold frame in March?

Yes, for zone 5–7 gardeners who want to extend the season. A cold frame — essentially an unheated greenhouse on the ground — raises the minimum temperature by 10°F or more and creates a zone 7 microclimate in a zone 5 garden. Per Penn State Extension, cold frames "allow harvesting of lettuce and spinach 4–6 weeks earlier than open-garden planting."

Sources

1. Penn State Extension — Vegetable Planting
2. Cornell Cooperative Extension — Spring Planting Calendar
3. NC State Extension — Lettuce and Cool-Season Crops
4. Clemson HGIC — Cool-Season Vegetables
5. University of Minnesota Extension — Cucumbers
6. Oregon State Extension — Planting Calendar
7. Missouri Botanical Garden — Spring Bulbs