Start tomato plants from seed indoors or buy seedlings from a nursery

You can grow tomatoes by starting seeds indoors six to eight weeks before your last spring frost, or by buying seedlings already started at a garden center. Starting from seed costs less but takes longer and requires a warm, bright spot indoors. Buying seedlings means you skip the waiting and go straight to transplanting outside, though you pay more per plant.

If you start from seed, fill a seed tray or small pots with seed-starting mix (not garden soil), plant seeds about a quarter-inch deep, and keep the soil moist but not waterlogged. Place the tray in a warm spot—tomato seeds sprout best between 70 and 80 degrees Fahrenheit. Once seedlings emerge in five to ten days, move them under grow lights or a sunny window so they stay stocky and don't stretch toward the light.

Key Takeaways

  • Tomato seeds need warmth to sprout (70–80°F) and bright light once they emerge, or seedlings will become tall and weak.
  • Transplant seedlings outdoors only after your last frost date has passed and daytime temperatures stay above 50°F, because cold soil and air stunt growth.
  • Plant tomatoes in full sun (at least six to eight hours daily) and space them 24 to 36 inches apart so air flows around the leaves and prevents disease.
  • Water deeply at the soil level once or twice a week rather than daily shallow watering, and mulch around the base to keep moisture steady and reduce fungal problems.
  • Determinate varieties (bush types) need less pruning; indeterminate varieties (vining types) need regular removal of suckers to direct energy into fruit instead of leaves.

Harden off seedlings before moving them outside

Seedlings grown indoors are tender and will wilt or die if you move them straight into outdoor sun and wind. Instead, spend seven to ten days gradually exposing them to outdoor conditions. Start by placing them in a shaded, sheltered spot for an hour or two, then increase the time and light each day until they spend a full day outside.

Hardening off also means reducing water slightly during this period so the plants toughen up. By the end of the week, seedlings should handle full sun and outdoor air without stress. This step takes patience but prevents transplant shock and gives you stronger plants.

Plant seedlings in the ground after frost danger passes

Transplant seedlings outdoors only after your last spring frost date and when soil temperature reaches at least 60°F—ideally 65°F or warmer. Tomatoes planted in cold soil sit dormant and may rot before they grow. Check your local frost date through your county extension office or a frost-date calculator online.

Dig a hole slightly deeper than the seedling's root ball and bury the stem up to the first true leaves. Tomatoes can root along the buried stem, creating a stronger root system. Space plants 24 to 36 inches apart depending on the variety—check the seed packet or label for the mature width. Water gently after planting to settle the soil.

Choose a location with full sun and good drainage

Tomatoes need at least six to eight hours of direct sun daily to produce fruit and ripen properly. Less light means fewer flowers and smaller, slower-ripening fruit. Pick a spot that gets morning sun, which dries dew and reduces fungal disease.

Soil should drain well so water doesn't pool around the roots. If your garden stays wet or soggy, grow tomatoes in raised beds or containers filled with quality potting mix. Before planting, mix compost or aged manure into the top six to eight inches of soil to add nutrients and improve drainage. A soil test through your extension office tells you what nutrients your soil lacks.

Water deeply and consistently, not daily and shallow

Tomatoes need steady moisture—about one to two inches of water per week from rain or watering. Water deeply at the soil level once or twice a week rather than sprinkling daily, because deep watering encourages roots to grow down and makes plants more drought-tolerant. Shallow daily watering keeps roots near the surface and makes plants thirsty quickly.

Water early in the morning so foliage dries by midday, which reduces fungal disease. Avoid wetting leaves; aim the water at the base of the plant. Mulch with two to three inches of straw or wood chips around the plant (but not touching the stem) to keep soil moisture steady, regulate temperature, and reduce weeds. Inconsistent watering—wet, then dry, then wet again—causes problems like blossom-end rot and fruit cracking.

Support plants with stakes or cages as they grow

Most tomato varieties need support to keep fruit off the ground and improve air flow. Install stakes or cages early, right after planting, so you don't damage roots later. Wooden stakes, metal cages, and string trellises all work; choose based on the variety's mature height and your preference.

For indeterminate varieties (vining types that grow all season), use tall stakes or sturdy cages at least five to six feet high. For determinate varieties (bush types that stop growing at a set height), shorter cages work fine. Tie stems loosely to the support with soft ties or strips of cloth so the plant can expand without cutting into the stem.

Prune suckers on indeterminate varieties to focus energy on fruit

Indeterminate tomatoes grow side shoots called suckers where branches meet the main stem. These suckers grow into extra stems that produce leaves instead of fruit, spreading the plant's energy thin. Pinch or cut off suckers when they are small (two to four inches long) to direct the plant's strength into fewer stems and larger fruit.

Determinate varieties don't need heavy pruning because they naturally stop growing and focus on ripening fruit all at once. However, you can remove lower leaves once fruit sets to improve air flow and reduce disease. Never remove more than one-third of the plant's leaves at once, because leaves feed the fruit.

Harvest tomatoes when they reach full color

Pick tomatoes when they are fully colored but still slightly firm—they continue to ripen after picking. Ripe tomatoes come off the vine with a gentle twist. If frost threatens before fruit ripens, pick all tomatoes (even green ones) and ripen them indoors on a windowsill or in a paper bag with a ripe banana or apple, which releases ethylene gas and speeds ripening.

Harvest regularly to encourage the plant to keep flowering and producing. A single indeterminate plant can produce dozens of tomatoes over a season if you pick ripe fruit consistently. Store ripe tomatoes at room temperature, not in the refrigerator, because cold breaks down flavor and texture.

Frequently Asked Questions

Why are my tomato seedlings tall and spindly?

Seedlings stretch toward light when they don't get enough brightness. Move them closer to a sunny window or place them under grow lights just a few inches above the tops of the plants. Keep lights on for 14 to 16 hours daily. If seedlings are already tall, bury them deeper when you transplant outside—they will root along the buried stem and develop a stronger base.

What causes blossom-end rot on tomatoes?

Blossom-end rot is a dark, sunken spot on the bottom of the fruit caused by inconsistent watering and low calcium. Water deeply and regularly so soil stays evenly moist, and mulch to help retain moisture. Add crushed eggshells or a calcium supplement to the soil before planting. Once rot appears on fruit, that tomato cannot be saved, but consistent watering prevents it on new fruit.

Can I grow tomatoes in containers?

Yes. Use a pot at least five gallons for determinate varieties and ten gallons or larger for indeterminate types. Fill with quality potting mix, not garden soil. Container tomatoes dry out faster than in-ground plants, so check soil moisture every day or two and water when the top inch feels dry. Feed every two to three weeks with a balanced fertilizer because nutrients leach out with frequent watering.

How do I prevent early blight and other leaf diseases?

Water at soil level, not on leaves, and water early so foliage dries quickly. Remove lower leaves once fruit sets to improve air flow. Space plants far enough apart that air moves between them. Mulch to prevent soil from splashing onto leaves. If disease appears, remove affected leaves when ready and dispose of them in the trash, not the compost pile.

When should I stop pruning and fertilizing?

Stop pruning suckers about four to six weeks before your first fall frost so the plant can focus on ripening existing fruit rather than growing new stems. Stop fertilizing at the same time. If you fertilize too late, you encourage new leaf growth that won't have time to mature into fruit before frost ends the season.