Plant tomatoes after the last frost date in your area, when soil temperature reaches 60°F
The single biggest mistake is planting too early. Tomatoes planted in cold soil sit dormant, rot, or grow slowly while you wait for warmth that never comes. Check your local frost date — the date when the last freeze typically occurs in spring — by searching "[your city] last frost date" or asking your county extension office. Plant tomatoes one to two weeks after that date, when soil has warmed.
Soil temperature matters more than air temperature. A soil thermometer costs $10 to $15 and takes the guesswork out. Tomatoes need soil at least 60°F to grow, but 65°F to 70°F is better. If you plant into cold soil, the roots will not take up water or nutrients, and the plant will sit there looking fine while slowly dying.
If you live in a very hot climate, you can plant a second crop in late summer for a fall harvest, timing it so fruit matures before the first frost. In mild climates with no hard freeze, you can grow tomatoes year-round, but most gardeners in the United States follow the spring-to-fall season.
Key Takeaways
- Wait until soil temperature is 60°F or higher and the last frost date has passed, usually one to two weeks after the date your county publishes.
- Space plants 24 to 36 inches apart in rows three to four feet apart, depending on whether you plan to stake or cage them.
- Dig a hole deeper than the root ball and bury the stem up to the first true leaves, because tomatoes will root along the buried stem and grow stronger.
- Mix compost or aged manure into the soil before planting, and add a balanced fertilizer or a slow-release tomato fertilizer at planting time.
- Water deeply after planting and keep soil consistently moist but not waterlogged for the first two to three weeks while roots establish.
Spacing and layout: how far apart to plant
Tomatoes need air circulation to prevent disease, so spacing is not optional. Determinate varieties (bush types that grow to a set size) can be planted 24 inches apart. Indeterminate varieties (vining types that grow all season) need 30 to 36 inches between plants. If you are planting in rows, space rows three to four feet apart so you can walk between them and reach fruit without stepping on plants.
Closer spacing saves space but increases disease pressure, especially in humid climates where fungal problems thrive in still air. If you live in a wet region, lean toward the wider spacing. If you live in a dry climate, you can plant a bit closer.
Decide before you dig whether you will stake, cage, or let plants sprawl. Staked plants (tied to a single pole or string) need less space because they grow vertically. Caged plants need more room because the cage spreads outward. Sprawling plants need the most space but are the easiest to plant and require no support structure.
Soil preparation: what to mix in before planting
Tomatoes are heavy feeders and will exhaust poor soil by mid-summer. Before planting, work two to three inches of compost or aged manure into the top six to eight inches of soil. This adds organic matter that holds moisture and nutrients, and it feeds the plant slowly over the season.
At planting time, add a balanced fertilizer (something like 10-10-10) or a tomato-specific fertilizer according to the package rate. Tomato fertilizers are often higher in phosphorus and potassium than nitrogen, which encourages flowering and fruiting rather than leafy growth. Do not use fresh manure, which can burn roots and introduce disease.
If your soil is heavy clay, add extra compost to improve drainage. Tomatoes do not like wet feet, and clay soil that stays soggy will cause root rot and fungal disease. If your soil is sandy and drains too fast, compost helps it hold moisture longer. Most tomato problems start with soil that is either too wet or too poor.
Planting depth: why burying the stem matters
Bury the tomato stem deeper than it was growing in the pot. Remove the lower leaves and plant the stem up to the first set of true leaves (the leaves that look like tomato leaves, not the smooth oval seed leaves). Tomatoes will root along the buried stem, creating a stronger root system that can reach deeper water and nutrients.
This is one of the few things you can do at planting time that will measurably improve the plant's performance later. A tomato planted at the same depth as its pot will have a shallow root system and will stress during dry spells. A tomato planted deep will have roots that extend six to eight inches down and will be more drought-tolerant and stable.
If you have a leggy seedling (tall and thin from growing indoors under weak light), this is your chance to fix it. Plant it even deeper, removing more of the lower leaves. The plant will be shorter and bushier, and the deeper roots will support it better.
Watering after planting: the first three weeks
Water deeply after planting so the soil settles around the roots and eliminates air pockets. The soil should be moist to a depth of six to eight inches. Then water when the top inch of soil feels dry to your finger. For the first two to three weeks, the plant is establishing roots, and consistent moisture matters more than later in the season.
Once the plant is growing actively and producing flowers, you can let the soil dry out a bit more between waterings. This actually encourages deeper rooting and makes the plant more resilient. But in the first few weeks, keep it evenly moist.
Mulch around the plant with two to three inches of straw or wood chips, leaving a two-inch gap around the stem so air can circulate and the stem does not rot. Mulch keeps soil temperature stable, reduces water loss, and prevents soil from splashing onto leaves (which spreads fungal disease).
Hardening off seedlings before planting
If you grew seedlings indoors under lights, they are soft and will sunburn or wilt if you plant them directly into full sun. Harden them off by gradually exposing them to outdoor conditions over seven to ten days. Start with two to three hours of dappled shade, then increase to four to five hours of morning sun, then full sun for a few hours, then a full day in the sun.
This process toughens the leaves and stems so they can handle wind, sun, and temperature swings. A seedling that goes straight from a grow light to full sun will look bleached and stressed for weeks, even if it survives. A hardened-off seedling will take off when ready.
Planting in containers: adjustments for pots
Tomatoes grow well in containers if the pot is large enough. Use a pot at least 18 inches deep and 18 inches wide for determinate varieties, and 24 inches deep and 24 inches wide for indeterminate varieties. Fill it with potting mix (not garden soil, which compacts in containers), and plant the same way you would in the ground — deep, with lower leaves removed.
Container tomatoes dry out faster than in-ground tomatoes, so you will water more often, sometimes daily in hot weather. Add a slow-release fertilizer to the potting mix at planting time, because nutrients leach out of containers with each watering. Check the soil moisture by sticking your finger two inches deep; if it feels dry, water until it drains from the bottom.
Place the container where it will get at least six to eight hours of direct sun. Tomatoes need sun to produce fruit, and a shaded container plant will grow leaves but few tomatoes.
Frequently Asked Questions
Can I plant tomatoes in the same spot every year?
No. Tomatoes are susceptible to soil-borne diseases like early blight and fusarium wilt that build up in the soil. Rotate tomatoes to a different bed every two to three years, or grow them in containers with fresh potting mix. If you must plant in the same spot, remove the top six inches of soil and replace it with compost.
What if my seedlings are tall and spindly?
They did not get enough light indoors. Plant them deep anyway — remove the lower leaves and bury the stem up to the first true leaves. The deeper planting and outdoor sun will help them recover. For next year, use grow lights closer to the seedlings or a sunny south-facing window.
How long does it take for a planted tomato to produce fruit?
Most tomatoes flower three to four weeks after planting and produce ripe fruit six to eight weeks after that, so roughly three to four months from planting to first harvest. Early varieties are faster; late-season varieties take longer. This is why timing matters — you need enough warm weather left in the season for fruit to mature.
Should I remove the leaves at the base of the plant?
Yes, once the plant is established. Remove leaves that touch the soil or are within six inches of it, because they are most likely to pick up fungal disease from soil splash. Do this gradually over the first month, not all at once, so the plant does not go into shock.
What is the difference between determinate and indeterminate tomatoes?
Determinate tomatoes grow to a fixed size (usually two to three feet), flower all at once, and produce most of their fruit in a short window. Indeterminate tomatoes grow indefinitely, flower continuously, and produce fruit until frost. Determinate is better for canning; indeterminate is better for fresh eating all season. Both need the same planting depth and spacing rules.