What to Plant in March: Zone 6 Vegetable Garden Guide

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March in Zone 6 is all about preparation and early cool-season planting. Your last frost isn't until mid-April to early May, so you're working with cold frames, indoor starts, and a few hardy direct-sow crops.

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Quick Answer

In Zone 6, March is too early for most outdoor planting. Start warm-season crops indoors (tomatoes, peppers). Direct sow peas, spinach, and radishes outdoors in late March if soil is workable. Your last frost is April 15 – May 15.

Zone 6 March Overview

Last frost date: April 15 – May 15 (varies by location) Soil temp in March: 35-45°F

Start Indoors Now

March is prime seed-starting month for Zone 6. These need 6-8 weeks indoors before transplanting after last frost.

Start Early March (8-10 weeks before last frost)

• Tomatoes — Start under lights. Transplant late May.
• Peppers — Slow growers. Start now for strong transplants.
• Eggplant — Needs warmth. Keep soil 75-85°F for germination.
• Broccoli — Start early for spring harvest.
• Cabbage — Start now, transplant in April with protection.

Start Mid-Late March (6-8 weeks before last frost)

• Squash — Grows fast. Don't start too early or plants get leggy.
• Cucumbers — 3-4 weeks before transplant date.
• Melons — Start late March for June transplant.
• Basil — Needs warmth. Start indoors, transplant after frost.

Plant Outdoors in Late March

If your soil is workable (not frozen, not waterlogged), these cold-hardy crops can go out:

Direct Sow (Late March)

• Peas — Plant as soon as soil is workable. They tolerate frost.
• Spinach — Germinates in cold soil (35°F+). Plant now.
• Radishes — 30-day crop. First succession planting.
• Lettuce — Cold tolerant. Direct sow or transplant under row cover.
• Kale — Extremely cold hardy. Direct sow now.
• Arugula — Fast growing, frost tolerant.

With Protection (Cold Frame or Row Cover)

• Carrots — Sow under row cover for faster germination.
• Beets — Can handle light frost. Cover if temps drop below 25°F.
• Swiss chard — Tolerates cold but grows slowly until April.

What NOT to Plant Yet

These will die in a Zone 6 March frost:

• Tomatoes (outdoors)
• Peppers (outdoors)
• Beans
• Corn
• Squash
• Cucumbers
• Melons
• Basil (outdoors)

Wait until after your last frost date (mid-April to mid-May depending on your specific location).

March Tasks Checklist

Week 1:

• Start tomato and pepper seeds indoors
• Order seeds if you haven't already
• Clean and prep seed starting supplies

Week 2:

• Start broccoli, cabbage, eggplant indoors
• Begin hardening off any early indoor starts
• Test soil — amend if needed

Week 3:

• Start squash, cucumber seeds indoors
• Prep outdoor beds (remove debris, add compost)
• Set up cold frames if you have them

Week 4:

• Direct sow peas, spinach, radishes, kale
• Plant lettuce under row cover
• Start basil and herb seeds indoors

Indoor Seed Starting Tips for Zone 6

1. Light: 14-16 hours under grow lights. Windowsills aren't enough.
2. Heat mats: Peppers and eggplant need 75-85°F soil to germinate.
3. Don't start too early: Leggy, root-bound transplants perform worse than younger ones.
4. Harden off: 7-10 days of gradual outdoor exposure before transplanting.

Zone 6 March Advantages

1. Planning time — Use March to finalize your garden layout.
2. Strong transplants — Indoor starts get a head start on the season.
3. Early peas — March-planted peas produce before summer heat.

Common Zone 6 March Mistakes

1. Planting warm-season crops outdoors — One frost kills tomatoes and peppers. Wait.
2. Starting seeds too early — 8 weeks before last frost is the sweet spot for most crops.
3. Ignoring soil temperature — Air temp doesn't matter. Soil temp does. Use a soil thermometer.
4. Skipping hardening off — Indoor plants need gradual adjustment to outdoor conditions.

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Last updated: February 2026