What to plant in May in the US: by USDA zone

In the United States, planting in May depends entirely on your local USDA hardiness zone and average frost dates. For northern zones 3 and 4, May is the time to start cold-hardy crops and transplant warm-season vegetables late in the month as the final spring frosts pass. In contrast, southern zones 9 and 10 are transitioning away from spring planting, focusing instead on heat-tolerant summer crops or preparing for a midsummer sowing gap.

Zones 3 and 4 (northern tier, mountains)

The average last spring frost in USDA zones 3 and 4 typically occurs between mid-May and early June. At this stage, soil temperatures are slowly rising but remain too cold for direct sowing of warm-season crops. The strategy here is split between protecting cold-hardy seedlings outdoors and preparing tender crops indoors.

1. Cold-hardy root crops and greens

Direct sow hardy root vegetables like carrots, radishes, beets, and parsnips as soon as the soil is workable and no longer muddy. These crops germinate in cool soil, though they grow more slowly than they would in mid-spring. You can also direct sow spinach, kale, and Swiss chard. Protect these early beds with row covers if a hard freeze is predicted.

2. Brassica and onion transplants

Transplant hardened-off cabbage, broccoli, cauliflower, and Brussels sprouts into the garden. These crops can handle light frosts without damage. Onions, leeks, and shallots grown from sets or transplants should also be planted out early in the month to maximize their vegetative growth period before the summer solstice triggers bulb formation.

3. Indoor warm-season seed starting

In early May, start seeds of tomatoes, peppers, eggplants, and melons indoors or in a heated greenhouse. These tender crops require four to six weeks of indoor growth before they can be safely transplanted outdoors in June. Keep them under bright artificial lights to prevent them from becoming leggy.

Zones 5 and 6 (Midwest, Northeast, Mid-Atlantic)

For USDA zones 5 and 6, May is the busiest month of the gardening year. The average last frost date falls between May 1 and May 15. Once this date passes, the risk of a killing freeze drops significantly, permitting the planting of both cool and warm season crops in quick succession.

1. Warm-season nightshades

After the last frost date, and once soil temperatures consistently reach 60°F, transplant tomatoes, peppers, and eggplants into their permanent beds. If a late frost threatens, cover these tender transplants with cloches, bucket covers, or floating row covers. Avoid planting them in waterlogged soil, which can cause root rot and stunt early growth.

2. Cucurbits and sweet corn

Direct sow summer squash, zucchini, cucumbers, melons, and pumpkins. These seeds germinate quickly in warm soil. You can also direct sow sweet corn in blocks of at least four rows to ensure proper wind pollination. For an early start, some growers sow these crops in biodegradable pots indoors early in the month, transplanting the entire pot to avoid root disturbance.

3. Succession salad greens and bush beans

Direct sow bush beans and pole beans once the soil is warm. To maintain a continuous harvest of salad greens, use succession planting by sowing small batches of lettuce, radishes, and arugula every ten to fourteen days. As the sun grows stronger, plant these greens in the partial shade of taller crops like corn or trellised peas to prevent premature bolting.

Zones 7 and 8 (Upper South, Pacific Northwest)

By May, USDA zones 7 and 8 are well past their last frost dates. Soil temperatures are warm, and the spring planting window is closing as summer heat approaches. The focus shifts to long-season summer crops and heat-tolerant varieties.

1. Sweet potatoes and okra

May is the prime time to plant sweet potato slips. They require warm soil and air temperatures to thrive. Plant them in loose, well-drained soil or in raised mounds. Okra seeds can be direct-sown now, as they germinate best when soil temperatures are above 70°F. Soak okra seeds in water for 24 hours before planting to speed up germination.

2. Warm-season succession crops

Sow second rounds of bush beans, sweet corn, and summer squash to replace early spring crops that are finishing their production. This ensures a steady supply of fresh vegetables through mid-to-late summer. Keep these new plantings well-watered, as May sunshine can quickly dry out the top inch of soil.

3. Heat-tolerant greens

Standard lettuces and spinach will bolt quickly under the strong May sun in these zones. Switch to sowing heat-tolerant greens such as Swiss chard, Malabar spinach, and New Zealand spinach. These varieties produce edible foliage throughout the summer without turning bitter or running to seed.

Zones 9 and 10 (Gulf Coast, Southwest, Florida, California)

In USDA zones 9 and 10, May represents the end of the traditional spring gardening season. Temperatures are already high, often exceeding 90°F. The primary challenge is not frost, but extreme heat and dry conditions. Traditional cool-season crops will not survive, so gardeners must plant highly resilient varieties.

1. Tropical roots and heat-loving legumes

Plant heat-tolerant crops like cassava, jicama, and sweet potatoes. Legumes such as southern peas (cowpeas), yardlong beans, and lima beans thrive in the intense heat of May and will continue to produce when other crops fail. These crops also help fix nitrogen in the soil for the upcoming fall planting season.

2. Summer cover crops for soil protection

If you do not plan to grow vegetables during the hottest summer months, plant a heat-tolerant cover crop to protect your soil. Sunn hemp, cowpeas, and buckwheat are excellent choices. They shade the soil, suppress weeds, prevent erosion, and add organic matter when tilled back into the earth before fall planting begins in September.

3. Establishing shade and mulching systems

Install shade cloths over existing tomato and pepper plants to reduce sunscald and encourage fruit set. Many tomatoes stop setting fruit when daytime temperatures exceed 90°F. Apply a thick layer of organic mulch, such as straw or wood chips, to keep soil temperatures down and conserve moisture.

Essential May gardening jobs across the United States

Regardless of your USDA zone, completing these fundamental maintenance tasks in May will set your garden up for a successful summer:

• Hardening off: Always transition indoor-grown seedlings to the outdoors gradually over seven to ten days. Expose them to wind and sun for increasing intervals to prevent transplant shock.
• Mulching: Apply a three-inch layer of organic mulch around established plants. This conserves water, regulates soil temperature, and prevents weed seeds from germinating.
• Drip irrigation setup: Install drip irrigation or soaker hoses before plants grow too large. Watering at the soil level keeps foliage dry, which significantly reduces the risk of fungal diseases like powdery mildew.
• Weed management: Hoe or hand-pull weeds while they are small. Weeds compete with young vegetable crops for water, nutrients, and sunlight, and they can harbor pests.