Plant tomatoes in full sun, in soil that drains well, and away from plants that compete for water and nutrients.

Tomatoes need at least six to eight hours of direct sunlight each day to produce fruit and develop flavor. Less sun means slower growth, fewer flowers, and a smaller harvest. The best spot is one that gets morning sun — this dries dew from the leaves and reduces disease.

Soil matters as much as light. Tomatoes grow best in soil that holds moisture but does not stay waterlogged. If your garden soil is heavy clay, mix in compost or aged manure before planting. If it drains too fast, add compost to help it retain water. The soil should be loose enough that you can push your finger into it without much resistance.

Avoid planting tomatoes where you grew tomatoes, peppers, potatoes, or eggplants in the previous year. These plants share the same diseases and pests, and the soil may still carry them. If you have limited space, use a different part of the garden or grow tomatoes in containers.

Key Takeaways

  • Tomatoes need six to eight hours of direct sunlight daily; morning sun is preferable because it dries leaves and prevents fungal disease.
  • Soil should drain well but retain moisture; mix compost into clay soil and add compost to sandy soil before planting.
  • Do not plant tomatoes in the same spot where tomatoes, peppers, potatoes, or eggplants grew the year before.
  • Space plants two to three feet apart to allow air to move between them and reduce disease risk.
  • Containers work well if garden space is limited, as long as the pot is at least five gallons and has drainage holes.

Spacing and air circulation matter for disease prevention

Tomatoes planted too close together create a humid pocket where fungal diseases thrive. Space plants two to three feet apart, depending on the variety. Determinate varieties (bush types that stop growing at a set height) can be closer; indeterminate varieties (vining types that grow all season) need more room.

Good air circulation also means pruning lower leaves once the plant is established. Remove leaves within six to twelve inches of the soil line — these are most likely to touch soil and pick up fungal spores. Prune as the plant grows, but do not remove more than one-third of the foliage at once.

Avoid planting near competing plants

Do not plant tomatoes next to fennel, brassicas (cabbage, broccoli, kale), or corn. Fennel releases chemicals that slow tomato growth. Brassicas and corn compete heavily for nitrogen and water. Tomatoes planted near these crops often stay small and produce less fruit.

Basil, carrots, and marigolds are good companions. Basil may help repel some pests, and carrots do not compete for the same nutrients. Marigolds attract pollinators and may deter some insects.

Container growing as an alternative

If your garden gets less than six hours of sun or your soil is poor, containers let you control both light and soil. Use a pot at least five gallons in size — smaller pots dry out too fast and stress the plant. Make sure the pot has drainage holes in the bottom.

Fill containers with potting mix, not garden soil. Potting mix drains better and is lighter, making the pot easier to move if you need to chase the sun. You can place containers on a patio, deck, or even a south-facing balcony. Move them if they end up in shade as the season progresses and trees leaf out.

Timing and soil temperature

Plant tomatoes outdoors only after the last frost date in your area and when soil temperature reaches at least 60 degrees Fahrenheit. Cold soil slows root growth and can rot seeds. If you plant too early, the seedling may sit in cold soil for weeks without growing.

In most regions, this means planting in late spring — May or early June in northern areas, March or April in warmer zones. If you are unsure of your last frost date, contact your local cooperative extension office or search online for your zip code.

Preparing the planting hole

Dig a hole slightly deeper than the root ball of your seedling. Tomatoes can be planted deeper than they were growing in their pot — they will develop roots along the buried stem, which makes them stronger. Remove the seedling from its pot and gently loosen the roots with your fingers.

Place the seedling in the hole so the lowest leaves are just above soil level. Fill the hole with soil, press gently to remove air pockets, and water well. If the seedling is tall and spindly, you can bury it at an angle — it will straighten as it grows and will root along the buried stem.

Sun exposure throughout the season

Pay attention to how shadows move across your garden as the season progresses. A spot that gets full sun in spring may be shaded by trees or structures by mid-summer. If you notice your tomatoes are getting less light as weeks go on, consider moving container plants to a sunnier location.

In very hot climates (above 95 degrees Fahrenheit regularly), afternoon shade can actually help. Extreme heat can cause flowers to drop and fruit to sunscald. In these areas, a spot with morning sun and afternoon dappled shade is often ideal.

Frequently Asked Questions

Can I plant tomatoes in partial shade?

Tomatoes can survive in three to four hours of sun, but they will grow slowly, flower less, and produce fewer fruit. The fruit that does develop will be less sweet. Six to eight hours is the minimum for a decent harvest.

What if my soil is very acidic or alkaline?

Tomatoes prefer soil with a pH between 6.0 and 6.8. If your soil is very acidic (below 6.0), add lime. If it is very alkaline (above 7.0), add sulfur. A soil test from your local cooperative extension will tell you the pH and how much to add.

Can I plant tomatoes in the same pot year after year?

You can reuse the pot, but replace the potting mix each year. Old mix may harbor disease spores and will have lost nutrients. Fresh potting mix gives the new plant the best start.

How close can I plant tomatoes to a fence or wall?

Keep at least two feet between the plant and a wall or fence. Walls reflect heat and can stress the plant, and air cannot circulate behind the plant, which increases disease risk.

Do tomatoes need to be staked or caged where I plant them?

Indeterminate (vining) varieties need support — stakes, cages, or trellises — no matter where you plant them. Determinate (bush) varieties may not need support if they have good air circulation, but staking keeps fruit off the ground and makes harvesting easier.