Start with a pot at least 5 gallons, with drainage holes in the bottom

A tomato plant needs room for its roots to spread and for water to drain away from the soil. The minimum size is a 5-gallon container — roughly 12 inches across and 12 inches deep. Larger is better: a 10-gallon pot gives the plant more stable footing and holds moisture longer between waterings, which matters in hot weather. The pot must have drainage holes; without them, water pools around the roots and causes rot.

Fabric pots and terracotta both work. Fabric pots dry out faster, so you water more often. Terracotta is heavier and breaks if you drop it, but it looks finished and lasts for years. Plastic pots are cheap and light, though they can crack in direct sun after a season or two. Whatever you choose, make sure it has at least two drainage holes.

Fill the pot with potting soil, not garden soil

Use potting soil — the bagged mix sold for containers — not soil from your garden or yard. Garden soil compacts in a pot and blocks drainage. Potting soil is loose and drains fast. Fill the pot to about 2 inches below the rim, leaving room for water to pool on top without spilling over.

If you are planting a seedling (a small plant from a nursery), dig a hole in the soil deep enough that the seedling sits at the same depth it was in its original small pot. If you are planting a leggy seedling — one that is tall and thin — you can bury it deeper, up to the first set of true leaves. Tomato plants will grow roots all along a buried stem, which strengthens the plant.

Space the plant in the center of the pot

One tomato plant per pot is the standard. Plant it in the center so it gets light from all sides. If the pot is against a wall or fence, position the plant slightly toward the open side so it does not lean away from the wall as it grows.

Determinate varieties — compact, bush-type tomatoes that stay 3 to 4 feet tall — fit comfortably in a 5-gallon pot. Indeterminate varieties — tall, vining types that grow 6 feet or more — need a 10-gallon pot and a sturdy cage or stake. Check the seed packet or plant label to know which type you have.

Water thoroughly after planting, then keep soil moist

After you plant the seedling, water the pot until water runs out the drainage holes. This settles the soil and removes air pockets around the roots. For the first week, water every day or every other day, depending on how fast the soil dries. Once the plant is established, water when the top inch of soil feels dry to your touch.

In hot weather, a large tomato plant in a small pot may need water every day. In cool weather or shade, it may need water only twice a week. The goal is moist soil, not soggy. Soggy soil causes root rot; dry soil stresses the plant and causes blossom-end rot on the fruit.

Add a cage or stake before the plant gets tall

Install support within the first week of planting. A cage or stake driven into the soil early avoids damaging roots later. For determinate varieties, a 4-foot cage is usually enough. For indeterminate varieties, use a 6-foot cage or a sturdy stake and tie the main stem loosely to it as the plant grows.

If you wait until the plant is 2 or 3 feet tall to add support, you risk breaking branches when you tie them or when the cage shifts. Early support also keeps the plant from sprawling across the ground, where leaves stay wet and disease spreads.

Place the pot where it gets at least 6 hours of direct sun

Tomatoes need sun to produce fruit. A pot in full sun (6 to 8 hours daily) will bear more fruit than one in partial shade. Full sun also dries the leaves faster after rain or watering, which reduces fungal disease.

In very hot climates (above 90°F regularly), afternoon shade can help prevent sunscald on the fruit, but morning sun is still important. If your only spot is in shade for part of the day, choose a determinate variety, which needs less light than indeterminate types.

Fertilize every 2 to 3 weeks once flowers appear

Potting soil contains some nutrients, but a tomato plant in a pot uses them up faster than a plant in the ground. Once the plant flowers, feed it every 2 to 3 weeks with a balanced fertilizer (such as 10-10-10) or a tomato-specific formula. Follow the label rate for container plants, which is usually lower than for garden beds.

Too much nitrogen (the first number) produces lots of leaves but few flowers. A balanced or slightly higher phosphorus formula (the middle number) encourages flowering and fruiting. Stop fertilizing in late summer so the plant focuses energy on ripening fruit rather than new growth.

Key Takeaways

  • Use a pot at least 5 gallons with drainage holes; 10 gallons is better for indeterminate (vining) varieties.
  • Fill the pot with potting soil, not garden soil, and bury the seedling deep enough that it sits at the same depth as in its original pot, or deeper if it is leggy.
  • Water thoroughly after planting, then keep the soil moist but not soggy — water when the top inch feels dry.
  • Install a cage or stake within the first week to support the plant as it grows.
  • Place the pot in at least 6 hours of direct sun and fertilize every 2 to 3 weeks once flowers appear.

Frequently Asked Questions

Can I plant a tomato seed directly in a pot?

Yes. Plant the seed about a quarter-inch deep in moist potting soil. Keep the soil moist but not waterlogged until the seedling emerges, usually in 5 to 10 days. Once it has two sets of true leaves, thin out any extra seedlings so only one remains per pot.

What if my pot does not have drainage holes?

Drill or punch holes in the bottom before you plant. Without drainage, water sits around the roots and causes rot within a few weeks. If the pot is decorative and you want to keep it whole, use it as a cover pot and set a draining pot inside it.

How often should I water a tomato in a pot?

Water when the top inch of soil feels dry to your touch. In hot weather, that may be daily. In cool weather or shade, it may be twice a week. The exact schedule depends on pot size, soil type, sun exposure, and temperature — so check the soil rather than following a fixed calendar.

Do I need to prune tomato plants in pots?

Determinate varieties need little pruning. Indeterminate varieties benefit from removing suckers (shoots that grow between the main stem and branches) to focus energy on fruit production. Pinch off the top of the plant 4 to 6 weeks before your first frost date so it stops growing new flowers and ripens the fruit already on it.

Can I move a potted tomato plant if it is not getting enough sun?

Yes, but do it gradually. Move the pot to a sunnier spot over a few days rather than all at once, so the plant does not go into shock. A plant that has been in shade will burn if exposed to full sun when ready. Once it is acclimated, it will produce more flowers and fruit.