Start with the right soil and containers

Tomatoes need well-draining soil rich in organic matter. Use a potting mix made for vegetables or seed-starting, not garden soil from your yard — garden soil compacts in containers and holds too much water, which causes root rot. Fill containers at least 6 inches deep for seedlings, or 5-gallon buckets for mature plants.

If you are starting from seed indoors, use small pots or seed trays. Keep the soil moist but not waterlogged. Seeds germinate in 5 to 10 days at room temperature (around 70°F). Once seedlings sprout their first true leaves — the ones that look like actual tomato leaves, not the smooth seed leaves — move them to individual 3-inch pots under a grow light or bright window.

Key Takeaways

  • Tomato seeds sprout in 5 to 10 days indoors and need 6 to 8 weeks to grow large enough to transplant outside.
  • Harden off seedlings by gradually exposing them to outdoor conditions over 7 to 10 days before planting in the garden.
  • Plant tomatoes in full sun (at least 6 to 8 hours daily) and space them 24 to 36 inches apart so air circulates around the leaves.
  • Water deeply at the soil level once or twice a week rather than daily shallow watering, and mulch around the base to retain moisture and prevent disease.
  • Prune suckers on indeterminate varieties (vining types) and support plants with stakes or cages to keep fruit off the ground.

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. Hardening off means gradually exposing them to outdoor conditions over 7 to 10 days. Start by placing seedlings in a shaded, sheltered spot for 2 to 3 hours on day one. Each day, increase the time outside and move them into more direct sun. By day 7 or 8, they should spend the full day outside. Bring them in at night until nighttime temperatures stay above 50°F.

Transplant seedlings into the garden or larger containers once they have 4 to 6 true leaves and nighttime temperatures stay consistently above 50°F. In most regions, this happens 6 to 8 weeks after sowing seeds indoors. Bury the stem deeper than it was growing in the pot — tomatoes form roots all along the buried stem, which strengthens the plant.

Plant in full sun and space them properly

Tomatoes need at least 6 to 8 hours of direct sun daily to produce fruit and prevent disease. Choose a spot that gets morning sun, which dries dew from the leaves and reduces fungal problems. Space plants 24 to 36 inches apart depending on the variety — determinate types (bush varieties that grow to a fixed size) can be closer, while indeterminate types (vining varieties that keep growing) need more room.

Dig a hole slightly larger than the root ball and backfill with soil mixed with compost or aged manure. Water when ready after planting. If you are planting in containers, use at least a 5-gallon pot for determinate varieties and a 10-gallon pot for indeterminate types. Larger containers hold more moisture and nutrients, which means less frequent watering and feeding.

Water deeply and mulch to prevent disease

Water tomatoes deeply at the soil level once or twice a week rather than daily shallow watering. Deep watering encourages roots to grow down into the soil, making plants more drought-tolerant. Shallow, frequent watering keeps roots near the surface and makes plants thirsty quickly. Aim for 1 to 2 inches of water per week, including rain. In hot weather, you may need to water twice a week.

Water only the soil, never the leaves — wet foliage invites fungal diseases like early blight and powdery mildew. Lay a soaker hose or drip line at the base of each plant, or water with a watering can pointed at the ground. After watering, explore 2 to 3 inches of mulch (straw, shredded leaves, or wood chips) around the base, keeping it 2 inches away from the stem. Mulch keeps soil moist, regulates temperature, and prevents soil from splashing onto leaves during rain.

Support plants and prune for better fruit

Install stakes, cages, or trellises at planting time so you do not damage roots later. Determinate varieties need light support; indeterminate varieties need sturdy stakes 6 to 8 feet tall or heavy-duty cages. Tie stems loosely to the support with soft ties or strips of cloth — tight ties cut into the stem as it grows.

Indeterminate varieties produce suckers — shoots that grow between the main stem and branches. Removing suckers directs energy into fruit production and improves air circulation. Pinch off suckers when they are small (2 to 3 inches long) by hand. Determinate varieties produce fewer suckers and do not need heavy pruning. Once plants flower, you can remove lower leaves that touch the ground to improve air flow and reduce disease.

Feed regularly during the growing season

Tomatoes are heavy feeders and need nutrients throughout the season. Mix compost or aged manure into the soil before planting. Once plants start flowering, feed every 2 to 3 weeks with a balanced fertilizer (equal nitrogen, phosphorus, and potassium) or a tomato-specific formula. Follow the package directions for the amount — too much nitrogen produces leafy plants with few flowers.

Container-grown tomatoes need more frequent feeding because water drains nutrients from the soil. Feed every 1 to 2 weeks with a diluted liquid fertilizer. Watch for signs of nutrient deficiency: yellowing lower leaves (nitrogen), purple-tinged leaves (phosphorus), or brown spots on fruit (calcium). Calcium deficiency, called blossom-end rot, appears as dark, sunken spots on the bottom of fruit — prevent it by keeping soil consistently moist and mulching well.

Watch for pests and common diseases

Hornworms, whiteflies, and spider mites are the most common tomato pests. Check the undersides of leaves weekly for insects or sticky residue. Remove hornworms by hand or spray with insecticidal soap if infestations are heavy. Whiteflies and spider mites thrive in hot, dry conditions — misting plants in the morning and keeping soil moist helps prevent them.

Early blight and late blight are fungal diseases that cause brown spots on leaves and fruit. Early blight starts on lower leaves; late blight appears suddenly in cool, wet weather. Prevent both by watering at soil level only, removing lower leaves, spacing plants for air flow, and mulching to keep soil off leaves. If disease appears, remove affected leaves when ready and dispose of them in the trash (not compost). Fungicide sprays work best as prevention, applied every 7 to 10 days during humid weather.

Harvest when fruit is fully colored

Tomatoes are ripe when fully colored — red, pink, yellow, or orange depending on the variety — and slightly soft to the touch. Harvest by gently twisting the fruit or cutting the stem with pruners. Ripe tomatoes come off the vine easily; if you have to pull hard, they are not quite ready.

You can pick tomatoes at the "breaker stage" — when they first show color — and let them ripen indoors on a windowsill. This is useful if frost is coming or if you want to protect ripe fruit from birds and insects. Tomatoes ripen faster at room temperature (around 70°F) than in the refrigerator. Store ripe tomatoes at room temperature, not in the fridge, which damages flavor and texture.

Frequently Asked Questions

Can I grow tomatoes from store-bought tomatoes?

Yes, but only from heirloom or open-pollinated varieties. Hybrid tomatoes (most supermarket tomatoes) do not produce seeds that grow into the same plant. Scoop seeds from a ripe heirloom tomato, rinse them, dry them on a paper towel for a week, and store them in a cool, dry place. They will sprout the following spring.

Why are my tomato flowers dropping without making fruit?

Flower drop happens when nighttime temperatures drop below 55°F or rise above 75°F, or when plants are stressed by inconsistent watering or too much nitrogen fertilizer. Keep soil evenly moist, avoid over-fertilizing, and wait for warmer weather. Once temperatures stabilize, new flowers will set fruit.

How do I know if my tomato plant is determinate or indeterminate?

Check the seed packet or plant label — it will say "determinate" or "indeterminate." If you do not have that information, watch how the plant grows. Determinate varieties stop growing at a fixed height (usually 3 to 4 feet) and produce all their fruit at once. Indeterminate varieties keep growing taller throughout the season and produce fruit continuously until frost.

What should I do with green tomatoes at the end of the season?

Pick all remaining tomatoes before the first frost, even if they are still green. Spread them on a windowsill or in a cardboard box at room temperature. They will ripen over 1 to 3 weeks. If they do not ripen indoors, use them for fried green tomatoes or green tomato salsa.

Can I grow tomatoes in a pot on a balcony?

Yes, as long as the balcony gets at least 6 to 8 hours of direct sun. Use a pot at least 5 gallons for determinate varieties and 10 gallons for indeterminate types. Container plants dry out faster than garden plants, so check soil moisture daily and water when the top inch feels dry. Feed every 1 to 2 weeks because water drains nutrients from containers quickly.