Plant tomatoes after the last frost date in your area, when soil temperature reaches at least 60°F

Tomatoes are warm-season plants and will not grow in cold soil — they'll sit dormant or rot instead. The last frost date is the average date of the final spring frost in your area. You can find yours by searching "[your state] last frost date" or by calling your local cooperative extension office, which is run by your state's land-grant university.

Even if the air feels warm, check the soil temperature before planting. Soil thermometers cost $8 to $15 at garden centers. Push one 4 inches into the ground where you plan to plant. If it reads below 60°F, wait another week or two. Planting in cold soil is the single most common reason tomato seedlings fail to grow.

In most of the continental United States, this means planting between late April and late May. In warmer regions (southern Florida, southern Texas, southern California), you may plant in late winter or early spring. In short-season areas (northern New England, the upper Midwest), you may not plant until early June.

Key Takeaways

  • Wait until soil temperature is at least 60°F and the last frost date has passed, not just when the air feels warm.
  • Space plants 24 to 36 inches apart so air flows between them and disease does not spread.
  • Dig a hole deeper than the root ball and bury the stem partway up the plant, which creates a stronger root system.
  • Water deeply at the base of the plant after planting and keep soil consistently moist, not waterlogged, for the first two weeks.
  • Determinate (bush) tomatoes need less space and staking than indeterminate (vining) types, so choose based on your garden size.

Choose a location with at least six to eight hours of direct sun

Tomatoes need sunlight to produce fruit and to dry morning dew, which prevents fungal disease. Six hours is the bare minimum; eight or more is better. If your garden gets afternoon shade in summer, that is fine — the morning sun is what matters most.

Avoid planting tomatoes in the same spot year after year. Soil-borne diseases like early blight and fusarium wilt build up in the soil and will infect new plants. If you must plant in the same bed, replace the top 6 inches of soil or grow tomatoes in containers instead.

Prepare soil with compost and check drainage before planting

Tomatoes prefer soil that drains well but holds moisture. Before planting, dig a test hole 12 inches deep in your planting area and fill it with water. If the water drains completely within 24 hours, your drainage is good. If water sits after 24 hours, amend the soil with compost or aged bark to improve drainage, or consider raised beds or containers.

Mix 2 to 3 inches of compost into the top 8 to 10 inches of soil where you will plant. Compost adds nutrients and organic matter that help soil hold moisture and feed the plant over time. If your soil is very poor or you are unsure of its quality, a soil test through your cooperative extension costs $15 to $30 and tells you exactly what nutrients are missing.

Dig a hole deeper than the root ball and bury the stem partway

This is the single most important planting technique for tomatoes. Tomato stems can develop roots all along their length, so burying part of the stem creates a much stronger root system than planting at the soil surface.

Remove the seedling from its pot and look at the stem. If the seedling is 6 inches tall, you can bury it up to the first true leaves (the leaves that look like tomato leaves, not the round seed leaves at the very bottom). If the seedling is leggy or tall, you can bury it even deeper — up to the lowest set of leaves on the stem. Pinch off any leaves that would be buried underground.

Dig a hole as deep as the buried portion of the stem will be, plus the depth of the root ball. Place the seedling in the hole so the buried stem is vertical and the top leaves are above soil level. Backfill with soil and press gently to remove air pockets.

Space plants 24 to 36 inches apart depending on type

Determinate tomatoes (bush types that grow to a fixed size and produce all fruit at once) need 24 inches between plants. Indeterminate tomatoes (vining types that grow all season and need staking or caging) need 30 to 36 inches between plants so air flows around them and disease does not spread.

If you are unsure which type you have, check the seed packet or plant label. It will say "determinate" or "indeterminate," or it may say "bush" or "vining." Spacing matters because crowded plants stay wet longer after rain or watering, which invites fungal disease.

Water deeply after planting and keep soil consistently moist for two weeks

After planting, water the soil around the base of the plant until it is wet 6 to 8 inches deep. This settles the soil around the roots and removes air pockets. Water at the soil level, not on the leaves — wet foliage invites disease.

For the first two weeks after planting, keep the soil consistently moist but not waterlogged. Stick your finger 2 inches into the soil; if it feels dry, water. If it feels wet, wait. After two weeks, the plant is established and you can water less often but more deeply — about 1 to 2 inches per week depending on rain and heat.

Mulch around the base of the plant with 2 to 3 inches of straw or wood chips, leaving 2 inches of bare soil around the stem. Mulch keeps soil temperature steady, reduces watering needs, and prevents soil from splashing onto leaves during rain.

Install support early for indeterminate varieties

If you are planting an indeterminate (vining) tomato, install a cage or stake at planting time, not later. Driving a stake into the ground after the plant is established damages roots. Tomato cages should be at least 5 feet tall for most indeterminate varieties; many store-bought cages are too short and collapse under the weight of fruit.

Determinate bush tomatoes usually do not need support, though some gardeners use a short cage or stake to keep fruit off the ground and reduce disease.

Frequently Asked Questions

Can I plant tomatoes in containers?

Yes. Use a pot at least 5 gallons for determinate varieties and 10 gallons for indeterminate types. Fill with potting soil, not garden soil. Container tomatoes dry out faster, so check soil moisture every day or two during hot weather. They also need feeding every two to three weeks because water drains nutrients away.

What if my seedling is very tall and leggy?

Bury it deeper than you normally would — up to the lowest set of true leaves. The buried stem will develop roots and create a stronger plant. Leggy seedlings usually mean the seedling did not get enough light indoors before planting.

Should I remove the bottom leaves before planting?

Only remove leaves that would be buried underground. Leaves above soil level help the plant photosynthesize and recover from transplant shock. You can remove lower leaves later in the season if disease appears on them.

How often should I water after the first two weeks?

Water deeply once or twice a week, depending on rain and temperature. Aim for 1 to 2 inches of water per week total. Consistent watering prevents problems like blossom-end rot and fruit cracking. Mulch helps keep soil moisture steady between waterings.

Can I plant tomatoes next to other vegetables?

Yes. Tomatoes grow well near basil, carrots, and parsley. Avoid planting them near brassicas (cabbage, broccoli) or fennel. Do not plant tomatoes where tomatoes, peppers, eggplants, or potatoes grew the previous year, as they share the same soil diseases.