What to plant in March in USDA zone 6

Sow indoors in March — zone 6

Start these seeds under lights or in a heated propagator so transplants are ready when the outdoor planting window opens.

• Tomatoes (early March), basil, cucumbers, squash (late month)

Sow outdoors in March — zone 6

Direct-sow these seeds into prepared garden beds or large containers. Soil temperature matters more than the calendar date — wait for a sustained warm-up before sowing tender crops.

• Peas, spinach, lettuce, radishes, kale, chard
• Carrots, beets, parsnips, turnips

Transplant in March — zone 6

Move hardened-off seedlings into the garden. Tender crops want soil above 16 °C and night temperatures consistently above 10 °C; cool-season transplants tolerate light frost.

• Onions, leeks, brassicas, potatoes

Universal March tasks

These apply across most US and UK gardens in March, regardless of zone.

• Start tomato, pepper, and eggplant seeds indoors (if not already).
• Direct-sow peas, spinach, lettuce, radishes once soil is workable.
• Transplant onions and leeks outdoors in zones 5-9.
• Plant bare-root fruit trees, berries, and asparagus crowns.
• Prune roses just before they break dormancy.
• Top-dress beds with compost and start hardening off transplants.

Why this works for zone 6

Zone 6 has average annual minimum temperatures of -10 to 0°F (-23 to -18°C) and a frost-free window from mid- to late April to mid- to late October — about 180 growing days. Two-season growing — cool-season crops in spring/fall, warm-season in summer. Heirloom tomato varieties work well here.

Dates are zone-wide averages. Local microclimates (south-facing slopes, urban heat, lakeside warmth, elevation) can shift the window by 1-2 weeks within the same zone.

UK gardeners — March

March opens outdoor sowing for most of the UK. Direct-sow peas, broad beans, spinach, radishes, and early carrots under cloches. Indoor: tomatoes, peppers, aubergines, cucumbers. Plant first early potatoes mid-month.

Source and methodology

Frost-date averages from NOAA Climate Data Online within USDA zone 6. Hardiness boundaries from the USDA Plant Hardiness Zone Map (2023). Crop timing curated against US Cooperative Extension Service publications (UNL, UMN, NC State, Texas A&M, UF/IFAS, Oregon State) and cross-referenced against the RHS sowing calendar. Curated by the Growli editorial team.

Keep going

• ← February in zone 6
• April in zone 6 →
• All zones — what to plant in March
• USDA Zone 6 — frost dates and crop list
• Full 12-month planting calendar

Other zones — March

• What to plant in March in zone 3
• What to plant in March in zone 4
• What to plant in March in zone 5
• What to plant in March in zone 7
• What to plant in March in zone 8
• What to plant in March in zone 9
• What to plant in March in zone 10