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

The single most important rule for tomato planting is this: wait until the danger of frost has passed and the soil has warmed up. Tomatoes are warm-season plants. They will not germinate in cold soil, and a late frost will kill seedlings or transplants outright. In most of the United States, this means planting between mid-April and late May, but the exact date depends on where you live.

You can find your local frost date through the USDA Hardiness Zone Map or by searching "[your city] last frost date." Once you know that date, add one to two weeks—that gives the soil time to warm after the frost danger passes. Soil temperature matters more than air temperature. A soil thermometer costs about $10 and removes the guesswork. Tomatoes need soil at least 60°F to germinate, though 65°F to 70°F is ideal for faster growth.

Key Takeaways

  • Plant tomatoes one to two weeks after your area's last spring frost date, when soil temperature reaches 60°F or higher.
  • You can start seeds indoors six to eight weeks before your frost date, then move seedlings outside once soil has warmed.
  • A soil thermometer takes the guesswork out of planting and costs less than $15.
  • Tomatoes planted too early in cold soil will sit dormant, rot, or fail to sprout, wasting time and seed.

Starting seeds indoors versus buying transplants

You have two paths: start seeds indoors under lights, or buy seedlings from a nursery and transplant them outside. Starting seeds indoors takes about six to eight weeks before your frost date. You'll need seed-starting mix, containers with drainage holes, and a sunny windowsill or grow lights. Keep the soil moist but not waterlogged, and maintain temperatures around 70°F.

Buying transplants from a garden center or nursery is faster and requires less equipment. Look for stocky, green seedlings with a few true leaves (the second set of leaves that appear, which look like actual tomato leaves). Avoid tall, spindly plants or those already flowering—they're stressed and won't transplant well. Transplants are ready to go into the ground as soon as soil temperature allows, usually within a week or two of purchase.

Hardening off seedlings before moving them outside

Whether you grew seeds indoors or bought transplants, seedlings need a transition period before planting in the garden. This process, called hardening off, takes seven to ten days. Seedlings grown indoors are tender and will wilt or die if moved directly into outdoor sun and wind.

Start by placing seedlings in a sheltered, shaded spot outdoors for an hour or two. Each day, gradually increase their time outside and their exposure to direct sun. By day seven to ten, they should spend the full day and night outside. This toughens the stems and leaves so they can handle garden conditions. If a frost is forecast during hardening off, bring them back inside.

Planting depth and spacing in the garden

Tomatoes can be planted deeper than they grew in their pot—in fact, they should be. Bury the stem up to the first set of true leaves. Roots will form along the buried stem, creating a stronger root system. If your seedling is tall and spindly, bury it even deeper, at an angle if needed. The plant will straighten as it grows.

Space plants 24 to 36 inches apart, depending on the variety. Determinate (bush) tomatoes can be closer; indeterminate (vining) tomatoes need more room. Spacing matters because good air circulation reduces disease. Dig a hole slightly larger than the root ball, set the plant in, and backfill with soil. Water thoroughly after planting. Do not fertilize at planting time—wait two to three weeks, then feed every two to three weeks with a balanced fertilizer or one higher in phosphorus and potassium.

Regional planting timelines

Planting dates vary widely by region. In the South (zones 8 to 10), tomatoes can go in the ground in March or early April. In the Midwest (zones 5 to 6), wait until mid-May. In the North and high elevations (zones 3 to 4), late May or early June is safer. Coastal areas with cool summers may need to plant earlier to give tomatoes enough warm weeks to fruit before fall.

If you live in a hot climate where summers exceed 95°F regularly, you may plant a spring crop (as above) and a fall crop. For fall tomatoes, count backward from your first fall frost date. You'll need to start seeds in mid-summer so plants are ready to transplant in late summer, before heat peaks again in early fall.

What happens if you plant too early

Planting in cold soil is the most common mistake. Seeds will sit dormant and may rot before sprouting. Seedlings will yellow, stop growing, and become stressed. Even if they survive, they grow slowly and are more vulnerable to disease. You lose weeks of growth and gain nothing by planting early.

If you've already planted and a frost is forecast, cover plants with row covers, blankets, or even large pots overnight. Remove covers the next morning. This buys you a few degrees of protection and may save your plants if the frost is light.

Succession planting for a longer harvest

You don't have to plant all your tomatoes on the same day. Planting in waves—every two to three weeks from your frost date through early summer—spreads out your harvest. Early plantings mature in June and July; later plantings fruit in August and September. This is especially useful if you want fresh tomatoes over several months rather than all at once.

Stop planting new tomatoes about 12 weeks before your first fall frost. Plants started later than that won't have time to set and ripen fruit before cold weather arrives.

Frequently Asked Questions

Can I plant tomatoes in containers instead of the ground?

Yes. Use a pot at least 5 gallons for determinate varieties and 10 gallons for indeterminate types. Fill with potting mix (not garden soil), and follow the same planting depth and spacing rules. Container tomatoes warm up faster in spring, so you can sometimes plant a week or two earlier than in-ground plants. Water more often because containers dry out faster than garden soil.

What if my area doesn't have a clear frost date?

Search your city name and "last frost date" online, or contact your local cooperative extension office—they have frost data specific to your area. If you're in a region with unpredictable weather, wait until nighttime temperatures stay above 50°F for a week straight before planting.

Do I need to use fertilizer when I plant?

No. Fresh garden soil or potting mix contains enough nutrients for the first few weeks. Adding fertilizer at planting can burn roots. Wait until plants are 6 to 8 inches tall, then begin feeding every two to three weeks with a balanced or phosphorus-rich fertilizer.

Can I plant tomatoes in the same spot every year?

Not recommended. Tomatoes are prone to soil-borne diseases like early blight and fusarium wilt. Rotate tomatoes to a different bed each year, or wait at least three years before planting tomatoes in the same location. If you must replant in the same spot, remove the top 6 inches of soil and replace it with fresh soil.

What's the difference between determinate and indeterminate tomatoes?

Determinate (bush) tomatoes grow to a fixed size, usually 3 to 4 feet, and produce most of their fruit at once. They're good for canning. Indeterminate (vining) tomatoes grow continuously throughout the season, reaching 6 feet or taller, and produce fruit steadily until frost. Both are planted at the same time, but indeterminate types need staking or caging and more space.