Plant tomatoes after your last spring frost, when soil reaches 60°F and daytime temperatures stay above 50°F

The single most important date for tomatoes is your last spring frost date. Tomatoes are killed by frost—even a light one—so planting before that date wastes the plant and the money you spent on it. You can find your frost date by searching "[your city] last frost date" or by checking the USDA Hardiness Zone Map, which shows the average date frost stops in your area.

Beyond frost safety, tomatoes also need warm soil and air. Soil below 60°F slows root growth so much that the plant sits stunted instead of growing. Daytime air temperatures below 50°F stress the plant and slow flowering. Most gardeners wait until daytime highs are reliably in the 60s or 70s before setting transplants in the ground—usually one to two weeks after the frost date, depending on how fast your spring warms.

If you start from seed indoors, begin six to eight weeks before your last frost date. This gives the seedling time to grow strong before transplanting outside. If you buy transplants from a nursery, you can plant them directly once conditions are warm enough.

Key Takeaways

  • Never plant tomatoes before your last spring frost date, which you can find by searching your city name and "last frost date."
  • Wait until soil temperature reaches at least 60°F and daytime air temperatures stay above 50°F, usually one to two weeks after the frost date.
  • If starting from seed indoors, sow six to eight weeks before your last frost date so seedlings are ready to transplant when weather warms.
  • Transplants from a nursery can go in the ground as soon as conditions are warm enough; they do not need the indoor head start.
  • Planting too early in cold soil causes stunting and root rot; waiting a few extra weeks results in faster, healthier growth.

How to find your last frost date

Your last frost date is the average date of the last freezing temperature in spring for your specific location. It is not a may provide—frost can come late some years and early others—but it is the safest target for planting frost-sensitive crops like tomatoes.

The easiest way to find it is to search "[your city or zip code] last frost date" in any search engine. Most results will show the date directly. You can also check the USDA Plant Hardiness Zone Map at planthardiness.ars.usda.gov: enter your zip code, find your zone, and look up the frost date for that zone in the accompanying table.

If you live in a rural area or a small town, search for the nearest larger city instead. Frost dates can vary by elevation and proximity to water, but using the nearest town's date is close enough for most home gardeners. If you are uncertain, ask at a local garden center or cooperative extension office—they know the microclimates in your area.

Starting seeds indoors versus buying transplants

Starting from seed indoors gives you more variety choices and costs less per plant, but it requires grow lights, heat mats, and space on a sunny windowsill or shelf. You sow seeds six to eight weeks before your last frost date, keep them warm (70–75°F), and move them under lights once they sprout. By the time frost danger passes, you have sturdy seedlings ready to harden off and plant outside.

Buying transplants (also called seedlings or starts) from a nursery or garden center is faster and requires no equipment. You straightforward wait until after your last frost date, buy plants that are already a few inches tall, and plant them directly in the garden. This method costs more per plant but saves time and space indoors.

Either way, the outdoor planting date is the same: after your last frost date and when soil and air are warm enough. The difference is only when you start the process.

Soil temperature matters as much as air temperature

A tomato planted in cold soil will sit in the ground for weeks without growing, even if the air feels warm. Cold soil slows root development and can cause the roots to rot before they establish. A soil thermometer (available at any garden center for a few dollars) takes the guesswork out: stick it 4 inches into the soil in the morning and wait 10 seconds for a reading.

Aim for soil at least 60°F, though 65–70°F is better. If your soil is still cold a week after your frost date, wait another week or two. You can speed up soil warming by laying black plastic or landscape fabric over the bed for a few days before planting—it traps heat and raises the temperature faster.

Soil temperature also depends on your region and the time of year. In warm climates, soil may reach 60°F by late March or early April. In cooler climates, it may not reach that temperature until May or even early June. This is why the frost date alone is not enough—you have to check the actual soil temperature.

Regional planting windows

Planting dates vary widely by region because frost dates and soil warming happen at different times. In the warmest parts of the southern United States (USDA zones 9–11), the last frost date may be in February or March, and soil warms quickly. In the coldest parts of the north (zones 3–4), the last frost date may not arrive until late May or early June, and soil warming is slow.

Rather than memorizing a national schedule, use your own frost date and soil temperature as your guide. This approach works whether you live in Florida, Minnesota, or anywhere in between. If you are new to gardening in your area, ask neighbors or a local extension office what week they typically plant tomatoes—their experience is the most reliable local information you can get.

What happens if you plant too early

Planting tomatoes before soil and air warm up causes several problems. The roots grow slowly in cold soil, so the plant sits stunted instead of establishing. Cold, wet soil also encourages root rot and fungal diseases. The plant may survive, but it will be weeks behind a plant that was waited on and planted in warm conditions.

A frost after planting kills the entire plant—leaves, stems, and all. If the plant is small, it may regrow from the roots, but you lose weeks of growth. If it is larger, it usually dies outright. The safest approach is to wait until conditions are reliably warm, even if it means planting later than you would like.

Hardening off seedlings before planting

If you started seeds indoors under lights, the seedlings are tender and used to stable, protected conditions. Before planting them outside, they need to adjust to wind, direct sun, and temperature swings—a process called hardening off. This takes 7 to 10 days.

Start by setting seedlings outside in a sheltered spot (against a wall, under an eave) for an hour or two on a mild day. Each day, increase the time outside and expose them to more direct sun and wind. By day 7 or 10, they can spend the full day and night outside. Then plant them in the garden. Seedlings that are hardened off adjust to the garden much faster than those planted directly from an indoor shelf.

Frequently Asked Questions

Can I plant tomatoes before the last frost date if I use row covers or cloches?

Row covers and cloches do provide some frost protection, but they are not reliable enough for tomatoes. A hard frost can still kill the plant even under cover. It is safer to wait until frost danger has passed and then use covers only if an unexpected late frost is forecast.

What if my soil is still cold but the air is warm?

Wait for the soil to warm up. Warm air alone does not prevent root rot or slow growth in cold soil. Check soil temperature with a thermometer; if it is below 60°F, wait another week or two. You can speed warming by laying black plastic over the bed.

Is it better to plant in spring or summer?

Spring planting (after your last frost date) is standard because it gives tomatoes the full growing season to produce fruit before fall frost. Summer planting works only in warm climates with a long frost-free season. In most regions, planting in summer means the plant will not have time to mature before cold weather arrives.

Can I plant tomatoes in a container earlier than in the ground?

Container soil warms faster than ground soil because it is exposed to sun on all sides. You can plant in containers a week or two earlier than in the ground, but still wait until after your last frost date and until daytime temperatures are reliably warm. Use a soil thermometer to check container temperature the same way you would check garden soil.

What if I miss the planting window?

If you miss the spring window, you can still plant in early summer in most regions—just be aware that the plant will have less time to produce fruit before fall frost. In very warm climates, you may be able to plant a second crop in midsummer for a fall harvest. Check with a local extension office about whether a summer planting makes sense in your area.