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 when freezing temperatures stop for the season in your area. Tomatoes cannot survive frost. Plant too early and a late freeze will kill seedlings or transplants. Plant at the right time and you avoid that loss entirely.

You can find your last frost date by searching "last frost date" plus your zip code, or by contacting your local cooperative extension office. Once you know that date, count backward six to eight weeks — that is when to start seeds indoors if you are growing from seed. If you are buying transplants from a nursery, wait until one to two weeks before your last frost date to plant them outside.

Soil temperature matters as much as air temperature. Tomato seeds germinate poorly below 60°F, and transplants planted into cold soil often sit dormant or rot. Use a soil thermometer to check the ground temperature in the morning. If it reads below 60°F, wait another week or two before planting.

Key Takeaways

  • Your last spring frost date is the date to know — tomatoes planted before that date risk being killed by freezing temperatures.
  • Start seeds indoors six to eight weeks before your last frost date, or buy transplants one to two weeks before that date.
  • Soil temperature should be 60°F or warmer before you plant, which often happens a week or two after the last frost date.
  • In warm climates with no spring frost, you can plant tomatoes as early as late winter, but wait until soil warms to at least 60°F.

How to find your last frost date

Your last frost date depends on where you live. The continental United States is divided into hardiness zones, and each zone has a different frost date. A gardener in Maine may have a last frost date in late May, while a gardener in Georgia might have one in mid-April.

The fastest way to find your date is to search online for "last frost date" and your zip code. The Almanac, the National Weather Service, and your state's cooperative extension all publish this information. Write the date down — you will use it every spring.

If you cannot find your zip code, call your county's cooperative extension office. They can tell you the date and often have other planting information specific to your area. The extension office is a free resource run by your state's land-grant university.

Starting seeds indoors versus buying transplants

If you start tomato seeds indoors, begin six to eight weeks before your last frost date. Seeds need warmth, light, and moisture to germinate. Most gardeners use a heat mat set to 70–75°F and grow lights on a 14-hour timer. Once seedlings have their first true leaves, move them to a sunny window or keep the lights on.

Transplants started indoors need to be hardened off before planting outside — gradually exposed to outdoor conditions over seven to ten days. Start by placing them in a sheltered spot for an hour, then increase time and exposure each day. This prevents transplant shock and sunburn.

Buying transplants from a nursery is simpler if you do not have grow lights or space. Wait until one to two weeks before your last frost date to buy them, then harden them off for a week before planting. Nursery transplants are usually four to eight weeks old and ready to go into the ground.

Soil temperature and why it matters more than air temperature

A warm day does not mean the soil is warm. Air temperature can spike to 70°F while soil stays at 50°F. Tomatoes planted into cold soil often fail to grow, rot at the base, or sit stunted for weeks waiting for the soil to warm.

Check soil temperature with an inexpensive soil thermometer, available at any garden center. Push it four inches into the ground in the morning, wait two minutes, and read the result. Repeat this check for three to five days in a row. Once the soil stays at 60°F or above, you can plant.

In most climates, soil reaches 60°F one to three weeks after the last frost date. In cooler regions, it may take longer. If you plant too early and soil is cold, cover the ground with black plastic or landscape fabric for a week or two to trap heat and warm the soil faster.

Planting timing for different U.S. regions

Timing varies widely by region. In the upper Midwest and Northeast, last frost dates fall between mid-May and early June, so outdoor planting happens in late May or June. In the mid-Atlantic and upper South, frost dates are typically mid-April to early May, allowing planting in late April or May. In the Deep South and Gulf Coast, frost dates are in March or early April, so planting can happen in April or even late March.

In warm climates with no spring frost — southern Florida, southern California, southern Texas, and Hawaii — you can plant tomatoes in late winter or early spring. However, tomatoes also struggle in extreme heat. In these regions, many gardeners plant a spring crop (February to March) and a fall crop (July to August) to avoid the hottest months.

If you live in a region with a short growing season, choose early-maturing varieties that produce fruit in 60 to 75 days rather than 80 to 90 days. This gives you a better chance of harvesting before the first fall frost.

What happens if you plant too early or too late

Plant tomatoes before the last frost date and a freeze will kill seedlings or young transplants outright. Even a light frost (32°F to 36°F) damages tender growth. If frost is forecast after you have planted, cover plants with blankets, row covers, or cloches overnight and remove them in the morning.

Plant too late and you shorten the growing season. Tomatoes need 60 to 90 days of warm weather to produce fruit, depending on the variety. If you plant in late June in a region where the first fall frost arrives in September, you may not harvest much before cold weather stops growth.

The sweet spot is planting as soon as soil is warm enough — usually one to three weeks after your last frost date. This gives plants the longest possible season to grow and produce without risking frost damage.

Hardening off transplants: the step most gardeners skip

Hardening off means gradually moving seedlings from indoors to outdoors over seven to ten days. Indoor plants live in stable conditions — no wind, consistent light, steady temperature. Outside, they face sun, wind, temperature swings, and lower humidity. Without hardening off, transplants wilt, turn purple or brown, or die.

Start by placing transplants in a sheltered, shaded spot outdoors for one to two hours. The next day, increase to three to four hours and move them to dappled shade. Each day, add an hour and move them into more direct sun. By day seven to ten, they should handle full sun and outdoor conditions all day. Bring them in at night until the last frost date has passed.

Water transplants more often during hardening off — outdoor air dries soil faster than indoor air. Check soil moisture daily and water when the top inch feels dry.

Frequently Asked Questions

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

Row covers and cloches trap heat and can protect plants from light frost, but they are not foolproof. If temperatures drop below 28°F, even covered plants may die. Use covers as insurance, not as permission to plant weeks early. Plant as close to your last frost date as soil temperature allows, then use covers only if an unexpected late frost is forecast.

What if my area does not have a clear last frost date?

Some regions have variable frost dates that shift by weeks from year to year. In these areas, use the average last frost date as your guide, but watch the weather forecast in spring. If frost is predicted after you plant, cover plants overnight. Many gardeners in these regions plant in stages — some transplants early, some mid-season — to spread risk.

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

In most climates, no — tomatoes need 60 to 90 days to produce fruit, and planting in mid-summer means the first frost will arrive before harvest. In warm climates with mild winters (southern Florida, southern California, southern Texas), you can plant a fall crop in July or August for winter harvest. Check your first fall frost date to see if you have time.

Does it matter what time of day I plant tomatoes?

Plant in late afternoon or on a cloudy day to reduce transplant shock. Planting in full midday sun stresses young plants. Water well after planting and keep soil moist for the first week while roots establish.

What if soil temperature is 60°F but the air is still cold?

You can plant, but growth will be slow until air temperature warms. Tomatoes grow fastest when both soil and air stay above 65°F. If air temperature is still in the 50s, wait another week or two. The extra wait is worth it — plants will grow faster and stronger in warm conditions than they would in cold soil and cool air.