Plant tomatoes after your last spring frost date, when soil temperature reaches 60°F or higher

The single most important date for tomato planting is your last spring frost date — the average date of the final frost in your area. Tomatoes cannot survive frost. Plant them too early and a late cold snap will kill seedlings or transplants. Plant them too late and you lose weeks of growing season.

In most of the United States, this means planting between mid-April and late May. In the Deep South and parts of the Southwest, it can be as early as February or March. In the upper Midwest and Northeast, it may not be safe until June. Your local cooperative extension office or a frost date lookup tool can tell you the exact date for your zip code.

Soil temperature matters as much as air temperature. Tomato seeds and transplants sit dormant in cold soil and may rot before they sprout. Wait until soil reaches at least 60°F, ideally 65°F or warmer. A soil thermometer costs under $15 and removes the guesswork.

Key Takeaways

  • Find your last spring frost date through your local cooperative extension office or a USDA frost date map — this is the hard important date for planting.
  • Soil temperature must reach 60°F or higher before you plant seeds or transplants, which usually happens one to two weeks after the last frost date.
  • In warm climates (zones 9 and 10), you can plant tomatoes in late winter or early spring; in cold climates (zones 3 and 4), wait until late May or early June.
  • Starting seeds indoors six to eight weeks before your frost date gives you larger transplants to set out, extending your harvest window.

Planting windows by region

Northeast and upper Midwest (zones 3–5): Plant between late May and early June. Frost danger persists into May in these regions. Starting seeds indoors in March or early April lets you transplant larger seedlings once soil warms.

Mid-Atlantic and Ohio Valley (zones 5–6): Plant between mid-May and early June. Soil typically reaches 60°F by mid-May in these areas. You have a narrower window than warmer regions but a longer one than the far North.

Southeast and lower Midwest (zones 6–7): Plant between mid-April and mid-May. Frost danger passes earlier here. Many gardeners in this zone also plant a second crop in late summer (late July or August) for a fall harvest, since tomatoes can tolerate light frost at the end of the season better than at the beginning.

South and Southwest (zones 8–10): Plant in late winter or early spring — February through April depending on your exact location. In the hottest parts of zone 10, tomatoes may stop setting fruit once temperatures exceed 95°F consistently, so planting early matters to get fruit before peak heat arrives.

Starting seeds indoors versus buying transplants

If you start seeds indoors, sow them six to eight weeks before your last frost date. Tomato seeds germinate best at 70–75°F and need light once they sprout. Seedlings should be sturdy and 6 to 8 inches tall by the time soil outdoors is warm enough to plant.

Buying transplants from a nursery or garden center skips the indoor step. You can plant them as soon as soil reaches 60°F and frost danger has passed. Transplants cost more per plant but save space, equipment, and attention. Either route works; choose based on your setup and budget.

Do not plant transplants outdoors while they are still in a heated greenhouse or under grow lights. Harden them off first by gradually exposing them to outdoor conditions over seven to ten days. A plant moved directly from warmth to full sun and wind will wilt and may not recover.

How to find your exact frost date

The USDA Plant Hardiness Zone Map divides the country into zones based on average annual minimum winter temperatures. Your zone gives you a rough planting window, but the last spring frost date is more precise for tomatoes.

Search "last frost date [your zip code]" or visit your state's cooperative extension website. Most states have an interactive map. Enter your zip code and you get a specific date — for example, May 15 or April 20. This date is an average, not a may provide; frost can occur a week or two later in some years. Conservative gardeners plant a week after the official date to be safe.

If you garden in a microclimate — a valley that collects cold air, a south-facing slope that warms early, or a spot sheltered by buildings — your actual frost date may differ from the official one. Watching what your neighbors plant and asking at local garden centers gives you real-world data for your specific spot.

Soil temperature and how to measure it

A soil thermometer inserted 4 inches deep tells you whether the ground is actually warm enough. Tomatoes germinate slowly below 60°F and may rot in cold, wet soil. At 65°F or warmer, they grow steadily. At 70°F or above, they grow fast.

Take the reading in the morning, in the spot where you plan to plant. Soil in a raised bed or under black plastic warms faster than bare ground. If your soil is still cool but your frost date has passed, you can warm it by laying black plastic over the bed for a week or two before planting.

Second plantings and fall crops

In zones 6 through 10, you can plant a second crop of tomatoes in mid-to-late summer for a fall harvest. Count backward from your first fall frost date (the date of the first frost in autumn) and plant 70 to 85 days before it, depending on the variety. A tomato that matures in 75 days planted on August 1 will produce fruit by mid-October.

Fall-planted tomatoes often have fewer pest and disease problems because many insects and fungi decline as temperatures drop. The trade-off is shorter days and less intense sun, so fruit ripens more slowly. Choose faster-maturing varieties for fall crops.

Common mistakes in timing

Planting too early is the most common error. Gardeners eager to start set out transplants while soil is still cold or frost is still possible. The plants sit stunted for weeks, and a late frost kills them outright. Waiting two weeks longer results in faster growth and a bigger harvest overall.

Planting in cold, wet soil causes seeds and transplants to rot before they establish roots. If you must plant early, use a soil thermometer to confirm warmth, not just the calendar date.

Buying transplants too early and keeping them indoors or in a greenhouse past their planting window creates leggy, stressed plants. Nurseries often sell tomato transplants weeks before it is safe to plant them outdoors. Buy them close to your planting date, or if you buy early, harden them off and plant them as soon as conditions allow.

Frequently Asked Questions

Can I plant tomatoes before the last frost date if I cover them?

Row covers, cloches, or frost cloth can protect plants from light frost (32–35°F) for a night or two. However, if a hard freeze (below 28°F) occurs, the cover will not save them. Covering buys you a few days of margin, not weeks. It is safer to wait until frost danger has genuinely passed.

What if I plant too early and frost kills my seedlings?

You can replant. If you started seeds indoors, you may have extra seedlings to set out. If you bought transplants, you can buy more. The delay costs you a few weeks of harvest, but tomatoes planted in warm soil grow fast enough to catch up. Replanting is better than losing the whole season to a frost-killed crop.

Do I need to wait for the soil to be warm if I am using transplants instead of seeds?

Transplants are more forgiving than seeds, but cold soil still slows their growth and can cause root rot. Wait until soil reaches at least 60°F. Transplants will grow in cooler soil, but they will sit dormant for weeks. Warm soil means faster establishment and faster growth overall.

Can I plant tomatoes in the fall where I live?

Only if your first fall frost date is at least 75 to 85 days away (depending on variety). Count backward from that date. If your first frost arrives in September, you do not have time for a second crop. If it arrives in November, you do. Check your fall frost date the same way you found your spring frost date.

What if my area does not have frost?

In frost-free zones (parts of southern Florida, southern California, and Hawaii), you can plant tomatoes almost any month. However, tomatoes still prefer soil temperatures between 60°F and 85°F and struggle in extreme heat. Plant in fall or winter in the hottest areas so fruit sets before peak summer heat arrives.