Starting a spring garden

Who this is for

Gardeners planning the spring planting, from seed starting in late winter to the first warm-season crops. Where frost is rare, planting follows heat and rain instead; see the regional notes.

Timing

Spring planting is counted from your typical last spring frost. The Frost dates page gives yours for any ZIP code: look up your frost dates.

That date is a middle value, not a safe date: the last frost comes after it in about half of years. Purdue’s frost maps use a date about 2 weeks later, when the chance of frost has dropped to about 1 in 10 ^[3]. So crops are grouped by how much cold they take. Hardy crops can go in 2–4 weeks before the average last frost, semi-hardy ones up to 2 weeks before it ^[1], tender ones on it, and the most tender about 2 weeks after ^[2].

Checklist

1. Look up your last spring frost and count from it. Frost dates by ZIP.
2. About 12–8 weeks before it, start onion seeds indoors; then peppers, broccoli and cabbage, tomatoes, lettuce, and basil (below).
3. Harden off transplants by setting them outside for longer each day over about 5–14 days before planting ^[9].
4. About 5–1 weeks before it, sow peas, then spinach, lettuce, radishes, onion sets, broccoli transplants, carrots, beets, and potatoes.
5. After it, wait for warm nights and soil before tomatoes, peppers, beans, squash, cucumbers, corn, and basil go out.
6. Watch the forecast after planting, and cover tender plants on cold nights. Frost alerts.

Seed starting

Weeks before your typical last spring frost:

• Onions: about 12–10 weeks ^[4].
• Peppers: about 8–6 weeks ^[6].
• Broccoli and cabbage: about 9–6 weeks, for transplants that go out a few weeks before the last frost ^[5].
• Tomatoes: about 7–5 weeks. Sources range from 8–6 weeks before the last frost ^[7] to 5–6 weeks before planting out ^[20].
• Lettuce: about 8–5 weeks, if you want transplants ^[4][5].
• Basil: about 6–8 weeks before you plant it out, which is after the last frost ^[8].

Where nights stay cool well after the last frost, start tomatoes, peppers, and basil later, so they aren’t overgrown by the time it’s warm enough to plant them out.

Before the last frost

• Peas: about 5–1 weeks before ^[1][10].
• Spinach, onion sets, radishes, lettuce: about 4–2 weeks before ^[1][10]. Sow lettuce and radishes a little at a time, and finish spring lettuce about a month before hot weather ^[16].
• Broccoli and cabbage transplants: about 4–1 weeks before ^[1][5].
• Carrots and beets: about 3 weeks before to the last frost ^[1][2].
• Potatoes: about 3–2 weeks before, once the soil is about 50°F ^[11].

After the last frost

• Beans, cucumbers, squash: from about the last frost date ^[2], once the soil is about 60°F ^[3][15].
• Tomatoes and peppers: tomatoes from about the last frost to 2 weeks after it, peppers about 2 weeks after ^[2][3], once nights stay above about 50°F and the soil is about 60°F ^[12].
• Sweet corn: once the soil is at least 60°F, about 65°F for supersweet types ^[13].
• Basil: once nights are warm; nights near 50°F can blacken the leaves ^[14].