What to plant in May

May is the primary planting month for warm-season vegetables in zones 5–7: tomatoes, peppers, beans, squash, cucumbers, corn, and basil. In zone 8–9, May means managing heat and succession planting. In zones 3–4, May is the cool-season window. Don't skip hardening off transplants

For most American gardeners in zones 5–7, May is the main planting month of the year. Last frost has passed or will pass this month, warm-season crops go in the ground, and the summer garden takes shape.

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The most important May rule

Per Penn State Extension, soil temperature matters more than calendar date. Tomatoes planted in cold soil (below 60°F) will sit and stall even if there's no frost. Beans planted below 60°F germinate poorly and rot in the ground. An inexpensive a soil thermometer is one of the most useful investments for any vegetable gardener.

Last frost dates and soil readiness for May planting:

• Zone 5 (Chicago, Denver): Last frost May 15–30. Soil reaches 60°F around May 15–20.
• Zone 6 (Philadelphia, Columbus): Last frost April 30. Soil typically hits 60°F by May 1–15.
• Zone 7 (Long Island, DC): Last frost April 1–15. Soil is usually 60°F+ by May 1.