Start with soil that drains well and feeds the plant all season

Large tomatoes need soil rich enough to sustain fruit growth for months, not just the first few weeks. Before planting, mix compost or aged manure into the top 12 inches of your garden bed — aim for a ratio of one part compost to two parts existing soil. Tomatoes pull nitrogen, phosphorus, and potassium steadily as they grow, so a single dose at planting time runs out by mid-summer.

Test your soil pH if you can; tomatoes prefer 6.0 to 6.8. If your soil is clay-heavy and stays wet after rain, add perlite or coarse sand to improve drainage — waterlogged roots rot and stop the plant from absorbing nutrients. A soil that crumbles in your hand and holds moisture without pooling is the target.

Once the plant is in the ground, side-dress with compost every three to four weeks during the growing season. Scatter a 2-inch layer around the base, keeping it 6 inches away from the stem to prevent rot and pest problems.

Key Takeaways

  • Space plants 24 to 36 inches apart so air flows between them and each plant gets full sun for at least six to eight hours daily.
  • Prune suckers (shoots that grow between the main stem and branches) on indeterminate varieties to direct energy into fewer, larger fruit instead of many small ones.
  • Water deeply and consistently — about 1 to 2 inches per week — so the soil stays evenly moist and prevents cracking and blossom-end rot.
  • Fertilize every three to four weeks with a balanced formula or one slightly higher in phosphorus and potassium once flowering begins.
  • Remove leaves below the first fruit cluster once the plant is established to improve air circulation and reduce disease pressure.

Space plants far enough apart that leaves stay dry

Crowded tomatoes compete for light and air, which weakens them and invites fungal disease. Plant indeterminate varieties (the tall, vining types) 36 inches apart in rows 4 feet apart. Determinate varieties (bush types that stop growing at a set height) can go 24 inches apart, but not closer.

Spacing matters less than sun. Tomatoes need six to eight hours of direct sunlight daily to produce large fruit with good flavor. Morning sun is especially valuable because it dries dew and reduces fungal problems. If your garden gets afternoon shade, plant on the south or west side of a fence or building to catch the longest light.

Prune suckers on tall varieties to concentrate growth

Indeterminate tomatoes grow indefinitely and produce suckers — small shoots that sprout where a branch meets the main stem. Each sucker becomes a branch with its own flowers and fruit. Left unpruned, the plant spreads energy across dozens of branches and produces many small tomatoes instead of fewer large ones.

Pinch off suckers when they are 2 to 4 inches long by hand or with pruning shears. Keep the main stem and the strongest branches, removing everything else. This forces the plant to channel nutrients into the fruit that remains. Stop pruning four to six weeks before your first frost date so the plant can ripen the fruit already set.

Determinate varieties naturally stop growing and do not need sucker removal — pruning them actually reduces yield.

Water deeply and on a consistent schedule

Tomatoes need 1 to 2 inches of water per week, delivered in one or two deep soakings rather than daily sprinkles. Shallow, frequent watering encourages roots to stay near the surface where they dry out quickly and the plant becomes stressed. Deep watering once or twice a week pushes roots down into cooler, moister soil.

Water at the base of the plant, not on the leaves. Wet foliage invites early blight and other fungal diseases. A soaker hose or drip line is ideal because it delivers water slowly to the root zone. If you use a sprinkler, water early in the morning so leaves dry before the heat of the day.

Inconsistent watering causes blossom-end rot (dark, sunken spots on the bottom of the fruit) and fruit cracking. Mulch around the plant with 2 to 3 inches of straw or wood chips to keep soil moisture steady and reduce temperature swings.

Feed the plant every three to four weeks once it flowers

A balanced fertilizer (equal parts nitrogen, phosphorus, and potassium) works at planting time, but once flowers appear, shift to a formula higher in phosphorus and potassium — something like 5-10-10 or 10-20-20. Phosphorus and potassium support flower and fruit development; too much nitrogen pushes leafy growth at the expense of fruit.

explore fertilizer every three to four weeks during the growing season. Follow the package directions for the amount based on your plant size. Liquid fertilizers work faster but need more frequent process; granular fertilizers release slowly and last longer. Compost side-dressing counts as fertilizer and is often enough if your soil started rich.

Remove lower leaves to improve air flow and reduce disease

Once the plant is 12 to 18 inches tall and has set its first fruit cluster, remove all leaves below that cluster. These lower leaves are the first to touch soil and pick up fungal spores. Removing them improves air circulation around the base of the plant and reduces early blight and other soil-borne diseases.

Continue removing leaves as the plant grows, always keeping the lowest 12 inches of the stem bare. This does not harm the plant — the upper leaves do most of the photosynthesis work anyway. The trade-off is worth it: better air flow means healthier plants and larger, disease-free fruit.

Support the plant so branches do not break under fruit weight

Large tomatoes are heavy. A single fruit can weigh a pound or more, and a branch loaded with three or four of them will snap without support. Use a sturdy cage, stake, or trellis system from the start — trying to tie up a plant mid-season damages roots and branches.

Cages sold in garden centers are often too flimsy for indeterminate varieties. A 6-foot stake driven 12 inches into the ground and tied to the main stem with soft cloth strips works better. As the plant grows, tie it loosely every 12 inches so the stem stays upright but can still move slightly in the wind.

Frequently Asked Questions

Why are my tomatoes small even though the plant looks healthy?

Small fruit usually means too much nitrogen or too many branches competing for energy. Cut back on high-nitrogen fertilizer and prune more aggressively on indeterminate varieties. Also check sun exposure — tomatoes need six to eight hours of direct light daily to size up.

What causes blossom-end rot and how do I stop it?

Blossom-end rot is a dark, sunken spot on the bottom of the fruit caused by inconsistent watering and calcium deficiency in the fruit. Water deeply and on a regular schedule so soil stays evenly moist. Mulch to reduce temperature swings. Once it appears on a fruit, that fruit cannot be saved, but consistent watering prevents it on new fruit.

Can I grow large tomatoes in containers?

Yes, but the container must be at least 5 gallons and ideally 10 gallons or larger. Use quality potting soil, not garden soil, and water more frequently because containers dry out faster than garden beds. Feed every two weeks because nutrients leach out with watering. Indeterminate varieties work better than determinate ones in containers.

When should I stop watering and feeding to let fruit ripen?

Stop fertilizing four to six weeks before your first frost date so the plant puts energy into ripening existing fruit rather than making new growth. Keep watering until frost arrives — the plant needs moisture to finish ripening the fruit on the vine.