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 tomato planting is your last spring frost date. Tomato plants die in frost. If you plant before that date arrives, a late freeze will kill seedlings or transplants you have already set in the ground. Your local cooperative extension office publishes this date for your county — search "[your county] last frost date" to find it.

Beyond frost safety, soil temperature matters as much as air temperature. Tomato seeds and transplants sit dormant or rot in cold soil. Plant when soil has warmed to at least 60°F; 65°F to 70°F is better. You can measure soil temperature with a soil thermometer from any garden center. If you plant too early into cold soil, the plant will not grow faster — it will just sit there for weeks.

Daytime air temperature should also stay consistently above 50°F. Tomatoes grow slowly and may yellow or drop flowers if nights dip below 55°F regularly. Wait until nighttime lows are reliably in the 55°F to 60°F range before transplanting.

Key Takeaways

  • Check your county's last spring frost date through your local cooperative extension — this is the hard important date below which frost will kill your plants.
  • Soil temperature must reach 60°F or higher before planting seeds or transplants, which usually happens one to three weeks after the last frost date.
  • In cold climates, start seeds indoors six to eight weeks before your last frost date so transplants are ready to go into the ground on time.
  • In warm climates with a second growing season, you can plant a fall crop in mid to late summer for harvest before the first fall frost.

How to find your last frost date

Your last frost date is published by the USDA and your state's cooperative extension system. Go to the Almanac's frost date tool (almanac.com/gardening/frostdates) or search your county name plus "last frost date." The result will be a specific date — for example, May 15 or April 20.

This date is an average based on 30 years of weather records. It is not a may provide. Frost can arrive after this date, though it is uncommon. Some gardeners plant a few days after the official date; others wait a week to be safer. If you have lost plants to late frost before, waiting an extra week is reasonable.

Starting seeds indoors versus buying transplants

If you start tomato seeds indoors, sow them six to eight weeks before your last frost date. This timing means seedlings will be large enough to transplant into the garden right around the frost date, when soil and air have warmed enough. Seeds started too early will become leggy and root-bound waiting for warm soil.

If you buy transplants from a garden center or nursery, you can plant them directly into the garden on or shortly after your last frost date, as long as soil temperature is 60°F or higher. Transplants skip the indoor seed-starting step, so you do not need to plan six to eight weeks ahead.

Soil temperature and when to plant

Tomato seeds germinate best in soil between 70°F and 80°F. Transplants tolerate cooler soil but grow very slowly below 60°F. If you plant a transplant into 50°F soil, it will sit there for weeks before roots begin to grow, even if air temperature is warm.

Soil warms more slowly than air, especially in spring. A week or two after your last frost date, air may be warm but soil may still be in the 50s. A soil thermometer takes the guesswork out. Push it 4 inches into the ground in the morning, wait five minutes, and read the temperature. If it is below 60°F, wait another week and check again.

In very cold climates where soil stays cool into late spring, you can warm the soil faster by laying black plastic mulch over the bed a week or two before planting. The plastic absorbs heat and raises soil temperature by several degrees.

Planting in warm and hot climates

In USDA zones 9 and warmer, tomatoes can be planted in spring as described above, but they often stop producing when summer heat arrives. Many gardeners in these regions plant a second crop in mid to late summer for a fall harvest. The fall crop avoids the worst heat and often produces better fruit.

To plant a fall crop, count backward from your first fall frost date. Tomatoes need 60 to 85 days from transplant to first ripe fruit, depending on variety. If your first frost date is November 15, plant transplants by mid-August. Check seed packets for days to maturity and work backward from your frost date.

Hardening off transplants before planting

If you started seeds indoors or bought tender greenhouse-grown transplants, they need to adjust to outdoor conditions before planting. This process is called hardening off. Set transplants outside in a sheltered spot for one to two hours on the first day, increasing time outdoors by a few hours each day over seven to ten days. This gradual exposure toughens the plant and prevents wilting or leaf scald when you plant it in the garden.

If you skip hardening off and plant a tender transplant directly into full sun and wind, it will wilt badly and may not recover. Even if it survives, it will be set back by a week or more. The extra time spent hardening off pays back in faster growth after planting.

What happens if you plant too early or too late

Planting before the last frost date risks losing plants to a late freeze. Even if frost does not kill the plant outright, cold soil and air slow growth so much that you lose weeks of production. A tomato planted into 50°F soil in April may not catch up to one planted into 70°F soil in May.

Planting too late means a shorter harvest window before fall frost arrives. In short-season climates, planting in late June or July may not give the plant enough time to produce fruit before the first frost. If your growing season is short, plant as soon as conditions allow rather than waiting.

Frequently Asked Questions

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

Row covers or frost cloth can protect plants from a light frost, but they do not warm the soil. If soil is still cold, the plant will not grow faster even if it survives frost. Plant when soil temperature is right, and use covers only as backup protection against an unexpected late frost.

What if my area does not have a published frost date?

Contact your county's cooperative extension office directly — they maintain frost date records even if they are not online. You can also ask local gardeners or a nearby nursery what date they use. If you have lived in the area for years, your own experience is valuable data.

Is it better to plant seeds or transplants?

Transplants are faster and more reliable for most home gardeners. Seeds require indoor space, grow lights, and careful timing. Transplants skip six to eight weeks of indoor work and give you a harvest only a few weeks later. Seeds make sense if you want specific varieties not sold as transplants or if you enjoy starting plants from scratch.

Can I plant tomatoes in containers instead of the ground?

Yes. Containers warm faster than ground soil in spring, so you can sometimes plant a week or two earlier. Use a container at least 5 gallons for determinate varieties and 10 gallons for indeterminate types. Follow the same soil temperature and frost date rules — the container just gives you a little flexibility on timing.

What if I plant too late and frost comes early?

If frost arrives before fruit ripens, pick all tomatoes — ripe, turning, and green — before the freeze. Ripe and turning tomatoes will keep in a cool room for weeks. Green tomatoes will ripen indoors on a windowsill or in a paper bag with a ripe banana or apple, which releases ethylene gas and speeds ripening.