The main factors that make tomatoes grow bigger

Tomato size comes down to three things: the variety you plant, how much sun and water the plant gets, and whether the soil has enough nutrients. Some varieties are bred to produce large fruit—beefsteaks and heirlooms like 'Brandywine' naturally grow bigger than cherry tomatoes. But even a large-fruited variety will stay small if it's crowded in shade, thirsty, or starving for nitrogen and phosphorus. The biggest tomatoes come from plants that get at least six to eight hours of direct sun each day, consistent water (not feast-or-famine), and soil that's been amended with compost or a balanced fertilizer before planting.

You also need to thin the fruit. A tomato plant that sets 50 small tomatoes will produce smaller fruit than one that sets 20 large ones, because the plant has only so much energy to divide among its fruit. Removing some flowers and young tomatoes early in the season forces the plant to put that energy into fewer, larger fruits instead.

Key Takeaways

  • Choose a large-fruited variety like 'Brandywine', 'Beefsteak', or 'Cherokee Purple' if size is your goal, because cherry and paste tomatoes are genetically small.
  • Plant in full sun (six to eight hours minimum) and amend the soil with two to three inches of compost before planting to provide steady nutrients.
  • Water deeply and consistently—about one to two inches per week depending on heat and rainfall—to avoid stress that stunts fruit size.
  • Remove some flowers and small fruit in early summer so the plant concentrates its energy on fewer, larger tomatoes instead of many small ones.
  • Feed with a balanced fertilizer or one slightly higher in phosphorus once the plant starts flowering to support bigger fruit development.

Choosing a variety that grows large fruit

Not all tomatoes are meant to be big. Cherry tomatoes ('Sweet 100', 'Sungold') and paste tomatoes ('San Marzano', 'Roma') are small by design—their genetics cap their size. If you want large tomatoes, start with a variety bred for it. Beefsteak tomatoes like 'Beefsteak', 'Big Beef', and 'Mortgage Lifter' regularly reach one pound or more. Heirloom varieties like 'Brandywine', 'Cherokee Purple', 'Ponderosa', and 'Black Krim' are also large-fruited, though they vary in shape and flavor.

Check the seed packet or nursery label for the expected mature size. If it says "cherry" or "grape", that plant will not produce large fruit no matter how well you care for it. Determinate varieties (bush types that stop growing at a set height) can produce large fruit, but indeterminate varieties (vining types that grow all season) often do better for size because they have more time and energy to develop bigger tomatoes.

Providing full sun and good air flow

Tomatoes need at least six to eight hours of direct sunlight daily to grow large fruit. Less sun means slower photosynthesis, which means less energy for the plant to put into fruit development. If your garden is partly shaded, choose the sunniest spot available and avoid planting near trees or tall structures that block afternoon light.

Space plants two to three feet apart to allow air to flow between them. Crowded plants compete for light and water, and poor air flow invites disease. If you're growing indeterminate (vining) varieties, prune the lower leaves once the plant is established—this improves air circulation around the base and directs more energy upward into fruit production rather than leaf growth.

Watering deeply and consistently

Tomatoes need steady moisture, not sporadic soaking followed by drought. Inconsistent watering causes problems like blossom-end rot (a dark, sunken spot on the bottom of the fruit) and cracking, and it also stresses the plant so it produces smaller fruit. Aim for one to two inches of water per week, depending on your climate and how hot it is. In very hot weather, you may need to water more often.

Water at the base of the plant, not the leaves, to reduce disease. A soaker hose or drip line is ideal because it delivers water slowly and directly to the soil. If you water by hand, water deeply—until the soil is moist six to eight inches down—rather than giving the plant a light sprinkle every day. Mulching around the base with two to three inches of compost or straw helps the soil hold moisture and keeps it cooler during heat waves.

Building soil with compost and nutrients

Tomatoes are heavy feeders and need nutrient-rich soil to produce large fruit. Before planting, work two to three inches of finished compost into the top six to eight inches of soil. Compost adds organic matter that helps soil hold water and nutrients, and it provides a slow, steady release of nitrogen, phosphorus, and potassium as it breaks down.

Once the plant is established and starts flowering, feed it every two to three weeks with a balanced fertilizer (like 10-10-10) or one slightly higher in phosphorus (like 5-10-10) to support fruit development. Follow the package directions for how much to use. Too much nitrogen pushes leafy growth at the expense of fruit, so avoid over-feeding. If you prefer organic methods, fish emulsion, seaweed extract, or compost tea applied every few weeks will provide steady nutrients without the risk of burning the plant.

Thinning flowers and young fruit

This is the step many home gardeners skip, but it makes a real difference in size. When your tomato plant flowers heavily in early summer, pinch off some of the flowers before they set fruit. Later, when small green tomatoes have formed, remove some of them too—aim to leave one tomato every four to six inches along the stem. This sounds wasteful, but it forces the plant to put all its energy into fewer fruits, and those fruits will be noticeably larger.

Start thinning in early summer when the plant is young and vigorous. If you wait until mid-season, the plant has already committed its energy to many small fruits and thinning will have less effect. Remove the smallest or most misshapen fruit, and leave the largest, most symmetrical ones. On indeterminate varieties, you can also remove some of the side shoots (suckers) that grow between the main stem and branches—this redirects energy into fruit rather than excessive foliage.

Pruning to direct energy into fruit

Indeterminate (vining) tomatoes benefit from selective pruning. Remove the lowest leaves once the plant is two to three feet tall—this improves air flow and reduces disease pressure at the base. As the plant grows, you can remove some of the side shoots (suckers) that grow in the crotch between the main stem and branches. Removing too many leaves will slow photosynthesis, so prune conservatively—remove only what's necessary to improve air flow and direct energy upward.

Determinate (bush) varieties need less pruning because they're genetically compact. Light pruning of the lowest leaves is usually enough. Avoid heavy pruning on either type late in the season, because the plant needs leaves to photosynthesize and ripen the fruit already on the vine.

Supporting heavy fruit with stakes or cages

Large tomatoes are heavy. A single beefsteak tomato can weigh one to two pounds, and a plant loaded with them will need sturdy support. Use a cage at least five feet tall, or drive a six-foot stake into the ground at planting time and tie the main stem to it loosely with soft twine or cloth strips as it grows. Check ties every few weeks and loosen them as the stem thickens—tight ties will cut into the stem and damage the plant.

If branches heavy with fruit start to bend or break, support them with slings made from old cloth or pantyhose tied to the stake. This prevents the fruit from touching the ground (where it can rot or be eaten by pests) and keeps the plant upright so it can continue producing.

Frequently Asked Questions

What's the difference between beefsteak and heirloom tomatoes?

Beefsteak is a category based on size and shape—large, flat, meaty fruit with few seeds. Heirloom refers to age and breeding history—older varieties passed down through generations. Many heirlooms are large-fruited, but not all beefsteaks are heirlooms. Both can grow very large; heirlooms often have more complex flavor but less disease resistance.

Can I grow large tomatoes in containers?

Yes, but the container must be large—at least five gallons, ideally ten or more. Use high-quality potting soil mixed with compost, water more frequently than in-ground plants (containers dry out faster), and feed every two weeks. Container plants often produce smaller fruit than in-ground plants because their roots have less room to spread and access fewer nutrients, but large-fruited varieties can still produce good-sized tomatoes with consistent care.

Why are my tomatoes staying small even though I water them?

Check three things: sunlight (less than six hours daily will stunt fruit), soil nutrients (work in compost or feed every two to three weeks), and whether you're thinning fruit (too many tomatoes on one plant means each one stays small). Also check for pests or disease—stressed plants put energy into survival rather than fruit growth.

When should I stop watering or feeding to help tomatoes ripen?

Keep watering consistently right through the season—stopping water late in the season stresses the plant and can cause cracking or blossom-end rot. You can reduce nitrogen feeding in late summer to slow new leaf growth, but continue watering deeply. Once frost threatens, stop feeding and let the plant focus on ripening the fruit already on the vine.

Do I need to use special fertilizer for large tomatoes?

No special fertilizer is required, but one slightly higher in phosphorus (the middle number) than nitrogen supports fruit development. A balanced 10-10-10 works fine. Avoid fertilizers very high in nitrogen, which push leaf growth at the expense of fruit. Compost and organic matter are often enough if your soil started out decent.