Plant tomatoes after your last frost date, which varies by region
The month you plant tomatoes depends almost entirely on when frost stops in your area. Tomatoes are warm-season plants that die if exposed to freezing temperatures, so planting before your last frost date will kill them. Your last frost date is the average date of the final frost in spring for your specific location — not your state or region, but your actual town or zip code.
In the warmest parts of the United States (southern Florida, southern Texas, southern California), you can plant in February or early March. In most of the middle and upper South, April is the standard month. In the North and at higher elevations, May is typical. In Alaska and high mountain areas, June may be necessary. The only way to know your exact date is to look it up for your location, not to guess based on what worked for a neighbor two towns over.
Key Takeaways
- Your last frost date determines when to plant, and it is specific to your zip code or town — not your state.
- You can find your last frost date free through the USDA Hardiness Zone Map or by searching "[your city] last frost date" online.
- Plant tomatoes one to two weeks after your last frost date, when soil temperature is at least 60°F and ideally 65°F or warmer.
- Starting seeds indoors six to eight weeks before your last frost date lets you transplant larger, stronger seedlings when outdoor conditions are safe.
- If you plant too early and frost threatens, cover plants with cloth or plastic to protect them overnight.
How to find your last frost date
The USDA Hardiness Zone Map is the standard tool. Go to planthardiness.ars.usda.gov, enter your zip code, and it will show your zone. From there, you can search "[your zone] last frost date" or "[your city name] last frost date" to find the specific date for your area. Many local cooperative extension offices also publish this information on their websites.
A faster method is to ask a local garden center or nursery what date they recommend for planting tomatoes in your area. They work with local conditions every year and can usually give you a reliable answer in one conversation. Some will even tell you when they expect to have transplants ready for sale, which is often timed to your local planting window.
The difference between seed starting and transplanting
You have two paths: start seeds indoors early, or buy transplants (seedlings) from a garden center and plant them directly outdoors. Starting seeds indoors takes six to eight weeks before your last frost date. If your last frost date is May 15, you would start seeds indoors around March 20 to April 1. This gives you larger, stronger plants to move outside when conditions are safe.
Buying transplants is simpler if you do not have indoor growing space or grow lights. Garden centers time their inventory to your region, so transplants are usually available in the weeks just before your last frost date. You can plant them directly into the garden one to two weeks after that date. Either way, the outdoor planting window is the same — after your last frost date when soil has warmed.
Soil temperature matters as much as the calendar date
Even if your last frost date has passed, tomatoes grow poorly in cold soil. Soil temperature should be at least 60°F, and ideally 65°F or warmer, before you plant. A soil thermometer costs five to ten dollars and takes the guesswork out. Push it into the soil in the morning, wait a few minutes, and read the temperature.
If your last frost date is May 1 but soil is still 55°F, wait another week or two. Planting in cold soil slows growth, invites root rot, and can stunt the plant for the entire season. Waiting for soil to warm is not wasted time — it actually gets you to harvest faster because the plant grows stronger from the start.
What to do if frost threatens after planting
Sometimes frost arrives unexpectedly after you have planted. If a frost warning is issued for your area, cover your tomato plants with cloth, plastic sheeting, or even old blankets before sunset. The cover traps heat radiating from the soil and can protect plants through a light frost. Remove the cover the next morning once temperatures rise above freezing.
Do not use plastic directly against the leaves if temperatures will drop below 28°F — plastic conducts cold and can damage the plant. Use cloth or a frost blanket instead, or create a frame with stakes so the plastic does not touch the foliage. This is a short-term emergency measure, not a long-term solution, so move the cover as soon as the frost risk passes.
Regional planting windows at a glance
| Region | Typical Last Frost Date | Typical Planting Month |
|---|---|---|
| Deep South (southern Florida, southern Texas) | February to early March | February to March |
| Upper South and Mid-Atlantic | Mid-April to early May | April to May |
| Midwest and Northern states | Mid-May to early June | May to June |
| High elevations and northern regions | Late May to June | June |
This table shows typical ranges, but your specific date will differ. Use the USDA map or a local source for your exact location rather than relying on your region alone.
Frequently Asked Questions
Can I plant tomatoes in March if I live in a warm state?
Only if your last frost date is in February or early March. Even in warm states, some areas have frost into April. Check your specific zip code rather than assuming your state is frost-free. A single frost after planting will kill the plants.
What if I plant too early and my tomatoes die?
You can replant. If you started seeds indoors, you may have backup seedlings. If you bought transplants, most garden centers restock throughout the season. The cost is frustrating, but it is cheaper than losing an entire crop to frost damage.
Do I need to harden off seedlings before planting them outside?
Yes. Seedlings started indoors are tender and will wilt or die if moved directly into full sun and wind. Spend seven to ten days gradually exposing them to outdoor conditions — start with a few hours in shade, then increase sun and time each day. This toughens the plant so it can handle the garden.
Can I plant tomatoes in summer if I missed the spring window?
In most regions, no. Tomatoes need time to grow, flower, and fruit before frost returns in fall. Planting in summer leaves too little time. In very warm climates with mild winters, you may be able to plant a fall crop, but this is uncommon and depends on your exact location.