Plant tomatoes after your last spring frost, when soil reaches 60°F

The best time to grow tomatoes depends on when frost stops in your area and soil temperature. Tomatoes are warm-season plants that die if exposed to frost, so planting too early is the most common mistake. You need two pieces of information: your last spring frost date and your soil temperature.

Your last spring frost date is the average date when frost stops occurring in your area. You can find this by searching "[your city] last frost date" or by contacting your local cooperative extension office. Once you know that date, wait until soil has warmed to at least 60°F before planting seedlings outdoors. Soil thermometers cost $10 to $20 and take the guesswork out of the decision.

In most of the United States, this means planting between late April and late May. In warmer regions like southern Florida or southern Texas, you may plant in February or March. In cooler regions like the upper Midwest or New England, you may not plant until June. The variation depends entirely on your local climate, not on a calendar date that works everywhere.

Key Takeaways

  • Tomatoes planted before your last spring frost date will be killed by cold weather, so waiting until after that date is essential.
  • Soil temperature matters as much as air temperature—seeds and seedlings rot in cold, wet soil even if daytime air feels warm.
  • You can start seeds indoors 6 to 8 weeks before your last frost date, then move seedlings outside after the frost date passes and soil warms.
  • Planting too early is far more common than planting too late, and it usually results in stunted plants or crop loss.
  • Your local cooperative extension office has the frost date for your specific area and can answer questions about your region's growing season.

How to find your last spring frost date

Your last spring frost date is specific to your location—sometimes even to your neighborhood. A town 10 miles away may have a different date. The easiest way to find it is to search "[your city] last frost date" online, which will usually return the date within the first few results.

If you cannot find it online, contact your county's cooperative extension office. In the United States, every county has one, and they maintain frost date records for your exact area. You can find your local extension office by searching "[your state] cooperative extension" and then selecting your county. They can also tell you typical soil temperatures for your area in spring.

Once you have the date, mark it on your calendar. This is your signal to check soil temperature before planting. Do not plant seedlings outdoors until both conditions are met: the frost date has passed and soil is at least 60°F.

Starting seeds indoors versus buying seedlings

You have two routes: start seeds indoors under lights, or buy seedlings from a nursery and plant them outside. Starting seeds indoors takes 6 to 8 weeks, so you would start them indoors 6 to 8 weeks before your last frost date. This gives you seedlings ready to plant the moment conditions are right outdoors.

Buying seedlings from a nursery is faster and requires less equipment. You skip the indoor step entirely and plant the seedlings outside after your frost date passes and soil warms. Seedlings cost $3 to $8 each, while a seed packet costs $2 to $4 and contains 20 to 50 seeds. If you are growing only a few plants, buying seedlings is usually cheaper and simpler.

If you start seeds indoors, use a seed-starting mix (not garden soil), keep soil moist but not waterlogged, and provide 14 to 16 hours of light per day under grow lights or in a bright window. Seedlings started in dim light will be weak and spindly. Once seedlings have their first true leaves (the second set of leaves that appear), you can thin them or transplant them into larger containers.

Hardening off seedlings before planting outside

Hardening off means gradually exposing seedlings to outdoor conditions so they adjust to wind, direct sun, and temperature swings. Seedlings started indoors are tender and will wilt or die if moved directly into the garden. Hardening off takes 7 to 10 days and is essential whether you started seeds indoors or bought seedlings from a nursery.

Start by placing seedlings in a sheltered spot outdoors for 1 to 2 hours on the first day. Each day, increase the time outside and the amount of direct sun they receive. By day 7 to 10, they should be outside all day and night. After hardening off, they are ready to plant in the garden.

If you skip hardening off, seedlings will experience transplant shock—they may stop growing, drop leaves, or die. The process is straightforward and takes only a few minutes each day, so it is worth doing even if it feels like an extra step.

Soil temperature and why it matters

Tomato seeds and seedlings planted in cold soil will rot before they grow. Soil below 60°F is too cold for tomato roots to absorb water and nutrients. Even if air temperature is warm and frost has passed, cold soil will stunt growth or kill young plants.

Check soil temperature with an inexpensive soil thermometer pushed 3 to 4 inches into the ground in the morning. If soil is below 60°F, wait another week or two before planting. Soil warms gradually as spring progresses, so waiting a few weeks makes a real difference in how fast seedlings establish and grow.

You can speed up soil warming by laying black plastic or landscape fabric over the planting area for 1 to 2 weeks before planting. The dark material absorbs heat and raises soil temperature. Remove it before planting, or cut holes in it to plant through.

Planting timing for different tomato varieties

Determinate tomatoes (bush types that produce all fruit at once) and indeterminate tomatoes (vining types that produce all season) both need the same frost-free conditions to plant. The difference is in how long they grow after planting. Indeterminate varieties need 70 to 85 days to first harvest, while determinate varieties need 60 to 75 days.

If your growing season is short, choose determinate varieties or early-maturing varieties labeled "60 days to maturity" or less. If you have a long, warm growing season, indeterminate varieties will produce fruit from summer through fall. Either way, plant after your last frost date and when soil is warm.

Cherry tomatoes and paste tomatoes have the same planting requirements as slicing tomatoes. Variety does not change when to plant—only your local frost date and soil temperature do.

What to do if you plant too early and frost returns

If you plant seedlings and frost is forecast within the next week, cover plants with row covers, blankets, or cloches (clear plastic domes) the night before frost arrives. Remove the covers during the day so plants get sun and air. This can protect young plants from light frost (32°F to 35°F).

If frost is severe (below 28°F) or lasts more than one night, covers may not save the plants. This is why waiting until after your last frost date is so much easier than trying to protect plants from unexpected cold. One hard frost can kill an entire crop of young tomatoes.

If plants are killed by frost, you can replant with new seedlings once soil warms again. This costs money and delays your harvest, which is why planting at the right time prevents a lot of frustration.

Frequently Asked Questions

Can I plant tomatoes in summer if I missed the spring window?

In most areas, no. Tomatoes need 60 to 85 days to produce fruit, and planting in summer means fruit would ripen in fall when temperatures drop and days shorten. In warm regions with long growing seasons (like southern Florida or southern California), you can plant a second crop in late summer for a fall harvest. Check with your local extension office about whether this works in your area.

What if I do not know my last frost date?

Search "[your city] last frost date" online, or contact your county cooperative extension office. They maintain frost records for your exact location and can tell you the date in one phone call. You can also ask neighbors who garden—they usually know from experience.

Is it okay to plant tomatoes when soil is 55°F instead of 60°F?

It is not ideal. Soil below 60°F slows root growth and increases the risk of rot. Waiting another week or two for soil to warm to 60°F gives seedlings a much better start. The few weeks you gain by planting early are usually lost to slow growth in cold soil.

Can I plant tomatoes in containers on a patio instead of in the ground?

Yes. Container soil warms faster than ground soil, so you may be able to plant a week or two earlier. Use a large container (at least 5 gallons) filled with potting mix, not garden soil. The same frost date still applies—do not plant until after your last spring frost, even in containers.

What happens if I plant tomatoes too late in the season?

If you plant very late (for example, in July in a northern state), plants may not have enough time to produce ripe fruit before the first fall frost arrives. Tomatoes need consistent warm weather to develop fruit. Planting in early summer gives you the longest window for growth and harvest.