Start with seeds or seedlings, not mature plants

You grow a tomato plant by starting with either seeds or small seedlings (young plants sold at garden centers), then moving it outdoors once the soil warms up, watering it regularly, and supporting the stem as it grows. Most home gardeners find seedlings easier than seeds because they skip the indoor starting phase, but both methods work. The whole process from planting to first harvest takes 60 to 85 days depending on the variety.

The choice between seeds and seedlings matters mainly for timing and space. Seeds need to start indoors 6 to 8 weeks before your last spring frost, under grow lights or in a sunny window. Seedlings skip that step—you buy them in late spring when they are already 4 to 6 inches tall, then plant them directly outside. If you have limited indoor space or are growing tomatoes for the first time, seedlings are the simpler route.

Key Takeaways

  • Tomato plants need at least 6 to 8 hours of direct sunlight daily and soil that drains well but stays consistently moist, not waterlogged.
  • Plant seedlings outdoors only after the soil temperature reaches 60°F and nighttime temperatures stay above 50°F, usually 1 to 2 weeks after your last frost date.
  • Water at the base of the plant early in the morning, aiming for 1 to 2 inches per week, and avoid wetting the leaves to prevent disease.
  • Support the main stem with a cage, stake, or string as the plant grows, and pinch off suckers (small shoots between the main stem and branches) on indeterminate varieties to direct energy into fruit.
  • Harvest tomatoes when they are fully colored but still slightly firm, and they will continue to ripen after picking if stored at room temperature.

Choose a location with full sun and good drainage

Tomato plants need at least 6 to 8 hours of direct sunlight each day to produce fruit and develop flavor. A south-facing or west-facing spot in your yard works best. If your garden gets afternoon shade, that is acceptable in very hot climates (above 90°F regularly), but morning sun is non-negotiable—it dries dew from the leaves and reduces fungal disease.

The soil must drain well but hold moisture. Heavy clay soil that stays soggy will rot the roots; sandy soil that dries out too fast will stress the plant and cause problems like blossom-end rot (a dark, sunken spot on the bottom of the fruit). Before planting, mix compost or aged manure into the top 8 to 10 inches of soil. This improves drainage in clay and water-holding capacity in sand. If you are planting in a container, use a potting mix labeled for vegetables, not garden soil.

Plant seedlings after the soil warms up

Tomato seedlings go in the ground only after nighttime temperatures stay consistently above 50°F and the soil has warmed to at least 60°F. Planting too early into cold soil shocks the plant and slows growth. Check your local frost date (search "[your city] last frost date") and wait 1 to 2 weeks after that date before planting outdoors.

Dig a hole slightly deeper than the seedling's root ball and bury the stem up to the lowest set of leaves—tomatoes will grow roots all along the buried stem, creating a stronger plant. Space plants 24 to 36 inches apart depending on the variety (check the seed packet or plant label). Water thoroughly after planting. If you are starting from seed indoors, harden off the seedlings by placing them outside in a sheltered spot for a few hours each day, gradually increasing exposure over 7 to 10 days before planting them in the garden.

Water consistently at the base of the plant

Tomatoes need 1 to 2 inches of water per week, delivered steadily rather than in one heavy soaking. Water early in the morning at the base of the plant, directing water to the soil rather than the leaves. Wet foliage invites fungal diseases like early blight and powdery mildew. If you use a soaker hose or drip line, water runs directly to the roots and stays off the leaves.

Check the soil 2 inches down with your finger—if it feels dry, water. If it feels moist, wait another day. Inconsistent watering causes problems: too little causes stress and blossom-end rot; too much causes root rot and splits in the fruit. In very hot weather, you may need to water every other day. In cool, rainy weather, you may not need to water for a week. Let the soil condition, not a fixed schedule, guide you.

Support the stem and manage growth

As the plant grows, the weight of fruit will bend or break the stem without support. Install a cage, stake, or string system when you plant the seedling, not later—waiting until the plant is large damages roots and branches. A tomato cage works for determinate varieties (bush types that grow to a fixed size and fruit all at once). Indeterminate varieties (vining types that grow continuously) do better with a stake or string tied loosely around the stem in a figure-eight pattern, which allows the stem to thicken without girdling.

On indeterminate varieties, pinch off suckers—small shoots that grow between the main stem and the branches—once the plant is 12 inches tall. Suckers do not produce fruit; they drain energy from the main plant and reduce air circulation. Pinch them off with your fingers when they are small. On determinate varieties, leave the suckers alone because they produce fruit. Stop pinching suckers in late summer (about 4 weeks before your first expected frost) to let the plant focus on ripening existing fruit rather than growing new branches.

Watch for common pests and diseases

Tomato plants attract hornworms (large green caterpillars), spider mites, and whiteflies. Check the undersides of leaves weekly for damage or insects. If you spot hornworms, remove them by hand—they are large enough to see and pick off easily. For spider mites or whiteflies, spray the undersides of leaves with water from a hose to dislodge them, or use insecticidal soap if the infestation is heavy.

Fungal diseases like early blight (brown spots with concentric rings on lower leaves) and powdery mildew (white coating on leaves) thrive in humid conditions. Prevent them by watering at the base only, spacing plants far enough apart for air to circulate, and removing lower leaves once the plant is established. If disease appears, remove affected leaves and dispose of them in the trash (not compost). Avoid touching wet plants, which spreads disease between plants.

Harvest when the tomato is fully colored

Pick tomatoes when they are fully colored but still slightly firm to the touch. A ripe tomato yields gently to pressure but is not soft. Harvest in the morning when the fruit is coolest. Tomatoes continue to ripen after picking if stored at room temperature (around 70°F), so you can pick them a day or two before they are fully ripe if you need the space on the plant.

In late summer, as the first frost approaches, pick all remaining tomatoes—even green ones. Bring them indoors and place them in a paper bag or on a windowsill at room temperature. They will ripen over the next 1 to 3 weeks. Once the plant is killed by frost, pull it out and dispose of it (again, not in compost, to avoid spreading disease to next year's plants).

Frequently Asked Questions

Can I grow tomatoes in a pot or container?

Yes. Use a pot at least 5 gallons for determinate varieties and 10 gallons for indeterminate varieties. Fill it with potting mix, not garden soil. Container plants dry out faster, so check the soil daily and water when the top inch feels dry. Containers also warm up faster in spring, so you can plant earlier than in-ground gardens.

Why are my tomatoes splitting or cracking?

Splitting happens when the plant receives too much water after a dry period, causing the fruit to absorb water faster than the skin can stretch. Water consistently rather than heavily after dry spells. Mulching around the base with 2 to 3 inches of straw or wood chips helps keep soil moisture even.

What is the difference between determinate and indeterminate tomatoes?

Determinate varieties grow to a fixed height (usually 3 to 4 feet), produce most of their fruit at once, and stop growing. They are good for canning and small spaces. Indeterminate varieties grow continuously throughout the season, producing fruit until frost, and can reach 6 feet or taller. They need more support and pruning but produce fruit longer.

Do I need to fertilize my tomato plant?

If you mixed compost into the soil before planting, you may not need additional fertilizer for the first month. After that, feed every 2 to 3 weeks with a balanced fertilizer (equal nitrogen, phosphorus, and potassium) or one higher in phosphorus and potassium to encourage fruiting. Follow the package directions for amount.

Can I save seeds from my tomatoes to plant next year?

Yes, but only from heirloom or open-pollinated varieties. Seeds from hybrid tomatoes will not produce plants identical to the parent. Scoop seeds and gel into a jar, add a little water, let them ferment for 2 to 3 days, rinse, and dry on a paper towel. Store in a cool, dry place and plant the following spring.