What to Plant in March: Zone 5 Vegetable Garden Guide
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March in Zone 5 is mostly about preparation and indoor seed starting. Your last frost isn't until mid-May, so outdoor planting is limited—but there's plenty to do.
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Quick Answer
In Zone 5, March is primarily for starting seeds indoors (tomatoes, peppers, brassicas) and preparing beds. Late March you can direct sow a few cold-hardy crops if soil is workable. Most outdoor planting waits until April-May.
Zone 5 March Overview
| Week | Outdoors | Indoors |
|---|---|---|
| Early March | Prep beds, remove mulch | Tomatoes, peppers, eggplant |
| Mid March | Test soil temp | Broccoli, cabbage, cauliflower |
| Late March | Peas, spinach (if soil workable) | Lettuce, kale starts |
Last frost date: May 15 (average for Zone 5) Soil temp in March: 35-45°F
Start Indoors Now (Priority)
These need 8-10 weeks indoors before transplanting:
Early March (10 weeks before last frost)
- Tomatoes
- Peppers
- Eggplant
- Onions (from seed)
Mid March (8 weeks before last frost)
- Broccoli
- Cabbage
- Cauliflower
- Brussels sprouts
Late March (6 weeks before last frost)
- Lettuce
- Kale
- Swiss chard
Indoor seed starting tips:
- Use grow lights—March sun through windows isn't enough
- Keep soil 65-75°F for germination
- Thin seedlings to prevent leggy growth
- Start hardening off in late April
Plant Outdoors (Late March Only)
Only if soil is thawed and workable (40°F+):
- Peas — Can handle frost. Plant along fence or trellis.
- Spinach — Direct sow, tolerates cold soil.
- Onion sets — Plant 1" deep, 4" apart.
Reality check: Many Zone 5 gardens still have snow in March. If ground is frozen, focus on indoor starts.
Prepare Your Garden
March is ideal for:
- Soil testing — Send samples to extension office. Results take 2 weeks.
- Bed prep — Remove winter mulch, add compost when soil is workable.
- Tool maintenance — Sharpen, oil, repair.
- Plan layout — Sketch your garden, order seeds if you haven't.
- Build trellises — Peas and beans will need support.
Wait Until April-May
Don't plant these yet:
| Crop | When to Plant |
|---|---|
| Lettuce transplants | Mid-April |
| Brassica transplants | Late April |
| Potatoes | Late April |
| Beans | Mid-May (after last frost) |
| Tomato transplants | Late May |
| Peppers, squash, cucumbers | Late May |
March Tasks Checklist
Week 1:
- Start tomatoes, peppers, eggplant indoors
- Order any remaining seeds
- Check stored seeds for viability
Week 2:
- Start brassicas indoors
- Begin removing winter mulch (if thawing)
- Test soil temperature
Week 3:
- Start lettuce, kale indoors
- Direct sow peas if soil is 40°F+
- Add compost to beds
Week 4:
- Sow spinach outdoors if workable
- Plant onion sets
- Prepare trellises for peas
Common Zone 5 March Mistakes
- Planting too early outdoors — Frozen soil kills seeds. Wait for 40°F.
- Skipping indoor starts — Your season is short. Indoor starts are essential.
- Forgetting hardening off — Seedlings need 7-10 days to adjust before transplanting.
- Not testing soil — March is the perfect time. You'll have results before planting.
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Last updated: February 2026