Plant tomatoes after your last frost date, when soil reaches 60°F
The single most important rule for tomato timing is this: plant after your last spring frost. Tomatoes die in freezing temperatures. If you plant too early and a frost hits, you lose the plant entirely. Your local frost date is the average date of the last freeze in spring for your area — find it by searching "[your city] last frost date" or checking the USDA Plant Hardiness Zone Map.
Beyond frost safety, wait until soil temperature reaches at least 60°F, ideally 65°F or warmer. Cold soil slows root growth and invites disease. You can measure soil temperature with a straightforward soil thermometer from any garden center. If you plant into soil that is still cold, the seeds or seedlings will sit dormant and may rot before they grow.
In most of the United States, this means planting between mid-April and late May, depending on where you live. Southern gardeners can plant earlier; northern gardeners plant later. The timing window is usually 2 to 3 weeks long — narrow enough that it matters, wide enough that you do not have to hit a single day.
Key Takeaways
- Plant tomatoes only after your last spring frost date and when soil temperature is 60°F or higher, or the plants will die or rot.
- Start seeds indoors 6 to 8 weeks before your frost date if you want mature seedlings ready to transplant on planting day.
- Tomatoes need 6 to 8 hours of direct sun daily, so choose your garden spot before planting season arrives.
- In hot climates, plant a second crop in late summer for a fall harvest, timing it so fruit matures before the first frost.
- Determinate (bush) tomatoes mature all at once; indeterminate (vining) tomatoes produce fruit all season until frost kills them.
Starting seeds indoors 6 to 8 weeks early
If you want to grow tomatoes from seed rather than buying seedlings, start seeds indoors in late winter. Count backward from your frost date: if your frost date is May 15, start seeds around March 20. Seeds need warmth (70°F to 80°F), moisture, and light to sprout — a sunny windowsill or a grow light works, though a heating mat under the seed tray speeds germination.
Seeds sprout in 5 to 10 days under warm conditions. Once they sprout, they need 14 to 16 hours of light daily to grow stocky, not tall and spindly. Water when the soil surface feels dry. In 6 to 8 weeks, seedlings should be 6 to 8 inches tall with their first true leaves (the second set of leaves that appear) and ready to harden off — a week-long process of gradually exposing them to outdoor sun and wind before planting.
If starting seeds feels like too much work, buy seedlings from a garden center or nursery 1 to 2 weeks before your planting date. Look for stocky plants with dark green leaves and no flowers yet — flowering seedlings often struggle after transplanting.
Choosing a planting location with full sun
Tomatoes need 6 to 8 hours of direct sun daily to produce fruit and develop flavor. Less sun means fewer tomatoes and more disease. Choose your garden spot before planting season, so you are not scrambling on planting day. If your garden is shaded by trees or buildings, move to a sunnier spot or grow tomatoes in containers that you can position in full sun.
Soil matters too. Tomatoes prefer soil that drains well and is rich in organic matter — compost, aged manure, or peat moss mixed in before planting helps. Soil pH should be between 6.0 and 6.8. If you do not know your soil pH, a straightforward soil test kit from a garden center costs a few dollars and takes 10 minutes.
Space plants 24 to 36 inches apart, depending on the variety. Indeterminate (vining) tomatoes need more space because they grow larger. Determinate (bush) tomatoes are more compact. Crowding plants invites fungal disease because air cannot circulate around the leaves.
Understanding determinate versus indeterminate varieties
Determinate tomatoes are bush-type plants that grow to a fixed size (usually 3 to 4 feet tall), flower all at once, and produce most of their fruit within 2 to 3 weeks. They are ideal if you want to harvest and preserve a large batch at once — perfect for canning or sauce-making. Plant them all on the same day and they will ripen together.
Indeterminate tomatoes are vining plants that grow continuously until frost kills them, flowering and producing fruit all season long. They can reach 6 feet or taller and need staking or caging. They produce a steady supply of tomatoes from mid-summer until the first frost. If you want fresh tomatoes on your table all season, choose indeterminate varieties.
The seed packet or plant label always says which type you are buying. If it does not say, ask the nursery staff. Knowing the difference changes how you plan your garden and when you expect to harvest.
Planting in spring versus planting a second crop in summer
In most climates, you plant once in spring and harvest until frost. But in warm regions — USDA zones 8 and warmer — you can plant a second crop in late summer for a fall harvest. Count backward from your first frost date in fall: tomatoes need 60 to 85 days from planting to first fruit, depending on variety. If your first fall frost is October 15, plant by late July or early August.
Summer planting has one advantage: cooler fall temperatures mean fewer pests and diseases. It has one disadvantage: you are planting into hot, dry soil, so seedlings need consistent water and afternoon shade for the first 2 to 3 weeks. Use shade cloth or plant where they get morning sun and afternoon shade until they are established.
If you live in a cool climate with a short growing season, skip the second crop. You will not have enough frost-free days for fruit to mature.
Protecting seedlings from late frost and cold snaps
Even after you plant, frost can return. If the forecast calls for freezing temperatures within a week of planting, cover plants with frost cloth, row covers, or even old blankets. Drape the cover over stakes so it does not touch the leaves, and remove it during the day so plants get sun and air. A frost cloth from a garden center costs $10 to $20 and lasts for years.
If frost hits an uncovered plant, the leaves will blacken and the plant may die. If only the top growth is damaged, cut off the dead leaves and the plant may regrow from the stem — but you lose weeks of growth. It is easier to cover plants for one cold night than to replant.
Check the 10-day forecast before planting. If a hard freeze is predicted within a week, wait. Tomatoes are not in a hurry, and neither should you be.
Timing harvest and understanding days to maturity
Every tomato variety has a days to maturity number on the seed packet — usually 55 to 90 days from transplanting to first ripe fruit. This is the time from when you plant the seedling in the garden, not from when you started the seed indoors. Count forward from your planting date to estimate when you will see ripe tomatoes.
If your first frost date is October 15 and a variety needs 80 days to mature, plant by mid-July to have time for fruit to ripen before cold weather. Varieties that need 90 days or more may not finish in short-season climates — check the seed packet before buying.
Tomatoes continue to ripen on the vine as long as temperatures stay above 50°F at night. Once nighttime temperatures drop below 50°F, ripening slows dramatically. If frost is forecast and you have green tomatoes on the vine, pick them and ripen them indoors on a windowsill — they will turn red over 1 to 3 weeks.
Frequently Asked Questions
Can I plant tomatoes before the last frost date if I use a cold frame or row cover?
You can plant 1 to 2 weeks early if you cover plants with a cold frame or heavy row cover, but the soil must still be 60°F or warmer. The cover protects from frost but does not warm cold soil. If soil is below 60°F, the plant will not grow even under a cover, and rot risk is high. Wait for warm soil.
What if I missed my planting window and it is already summer?
In cool climates, you have missed the season — tomatoes need too many days to mature. In warm climates (zones 8 and up), plant a summer crop for fall harvest, timing it so fruit matures before the first frost. Count backward from your fall frost date and choose a fast-maturing variety (60 to 70 days).
Do I have to start seeds indoors, or can I direct-seed tomatoes in the garden?
Direct seeding (planting seeds straight in the garden) works but takes longer — seeds need 5 to 10 days to sprout, then 8 to 10 weeks to grow into transplant-size plants. You lose 2 to 3 months of growing time. Starting indoors lets you transplant mature seedlings and harvest earlier. Most home gardeners start indoors or buy seedlings.
How do I know if my soil is warm enough without a thermometer?
A soil thermometer costs $5 to $10 and is the only reliable way. If you do not have one, wait until nighttime temperatures stay above 50°F for a week and soil feels warm to the touch. This is not precise, but it is better than guessing. Buy a thermometer — it works for all your garden crops.
Can I grow tomatoes in containers, and does timing change?
Yes, containers work well. Timing does not change — plant after your last frost date when soil temperature is warm. Containers warm up faster than garden beds, so you may be able to plant a few days earlier. Use a pot at least 5 gallons for determinate varieties, 10 gallons for indeterminate. Water containers daily in hot weather because they dry out fast.