May is Zone 6's great planting month. The last frost — average Apr 1–15 — is behind you, the soil is warm, and everything tender can go out. It is also the month when the first real harvests arrive, so May is both the busiest planting month and the first rewarding one.
What May means in Zone 6
Zone 6 sits in the middle of the American garden map — cold enough for a real winter, with average annual minimums of -10 to 0°F, but with a growing season long enough for tomatoes, peppers and winter squash to finish comfortably. The frost-free season lasts about six months, from mid-April into late October. The average last spring frost falls in the Apr 1–15 range and the average first autumn frost in the Oct 15–Nov 1 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.
With about six frost-free months ahead, Zone 6 May is about planting the summer garden properly and on time. Tomatoes, peppers, beans, corn and squash all need to be in the ground by late May to mature comfortably before the average first frost of Oct 15–Nov 1. At the same time, the cool-season crops sown in March and April — peas, lettuce, spinach, radishes and broccoli — are ready to eat, so the garden is giving as well as taking.
May task list
- Transplant tomatoes, peppers, eggplant and basil; mulch around them. 2. Direct-sow beans, corn, squash, cucumbers and okra. 3. Mulch everything with 2–3 inches of straw to hold moisture. 4. Set up stakes, cages and trellises. 5. Thin carrots and beets; side-dress corn and tomatoes with compost. 6. Watch for cutworms, flea beetles and aphids on young plants.
What to start indoors now
Indoor starting is nearly finished in May, but a few jobs remain. Start winter squash and pumpkins indoors in early May for the longest possible season — they need 90–120 days to mature. Start a second round of cucumbers and zucchini indoors for succession planting, and start herbs like basil indoors if you have not already. Harden off any remaining seedlings before they go out. 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 green beans (50–65 days), sweet corn (60–90 days), zucchini (45–55 days), cucumbers (50–70 days), okra (50–65 days) and pumpkins (90–120 days) now that the soil is warm. Sow carrots (60–80 days) and beets (50–70 days) for summer harvest, and keep sowing lettuce and radishes (25–40 days) every two weeks — move lettuce to afternoon shade as days warm. Sow dill, cilantro and parsley outdoors too. 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 tomatoes (60–85 days), bell peppers (60–90 days), eggplant (70–85 days) and basil into their final spots in early May, spacing tomatoes 24–36 inches apart. Set out sweet potato slips in mid-to-late May, once the soil is thoroughly warm — sweet potatoes need 90–120 days. Transplant any remaining brassica seedlings, and set out celery seedlings, keeping their soil consistently moist. 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
May harvests are generous: asparagus is still going in early May, peas are at their peak by late May, and lettuce, spinach, radishes, scallions and spring broccoli are all ready. Pick peas daily once pods fill out — they turn starchy fast. Harvest herbs in the morning, when their oils are strongest, and cut lettuce as outer leaves to keep plants producing. 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 6
Frost is rarely a May worry in Zone 6 after mid-month, but the average last frost of Apr 1–15 is an average — a cold night in early May is still possible, so keep frost cloth handy for the first two weeks after transplanting. The bigger May risk is cold, wet soil rotting tender seeds: beans and corn sown into soil that is still cool will rot rather than germinate, so wait until the soil feels warm to the touch. If in doubt, sow a few test seeds first. 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 Plant Spacing Calculator can help you time plantings around your frost dates.
Planting data for May in Zone 6
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 |
|---|---|---|---|
| Tomatoes | Transplant outdoors | 60–85 | Space 24–36 in; mulch after planting |
| Green beans | Direct sow | 50–65 | Sow after last frost; succession-sow |
| Sweet corn | Direct sow | 60–90 | Plant in blocks for pollination |
| Okra | Direct sow | 50–65 | Needs warm soil; soak seed overnight |
| Peas | Harvest | 60–70 | Pick daily; pods turn starchy fast |
| Pumpkins | Direct sow / start indoors | 90–120 | Needs the full season |
Browse the full planting calendar hub for every Zone 6 month, and see the neighbouring months in this zone:
Frequently asked questions
What should I plant in May in Zone 6?
Tomatoes, peppers, eggplant and basil as transplants, and beans, sweet corn, zucchini, cucumbers, okra and pumpkins direct-sown. Keep sowing lettuce, radishes, carrots and beets for a steady supply.
When can I plant tomatoes outside in Zone 6?
Early May, after the average last frost of Apr 1–15, once nights stay above freezing. Harden seedlings off for a week first and keep frost cloth handy for the first fortnight.
What can I harvest in May in Zone 6?
Asparagus, peas, lettuce, spinach, radishes, scallions and spring broccoli. Peas are the highlight — pick them daily while the pods are still sweet.
Is May too late to start seeds indoors in Zone 6?
For most crops, yes. The exceptions are pumpkins and winter squash, which benefit from an early-May indoor start because they need 90–120 days to mature.
How do I stop cutworms killing my transplants?
Put a cardboard collar around each stem, pushed an inch into the soil, and keep the area around transplants clear of weeds. Check plants in the morning — a seedling cut at the base overnight is the classic sign.