The three things that make tomatoes grow large

Tomatoes grow large when they have steady water, consistent nutrients, and enough time to mature before the season ends. A tomato that weighs a pound or more needs all three working together—skip one and you'll get smaller fruit even if the other two are perfect. The variety you choose matters too: beefsteak and heirloom types like 'Brandywine' and 'Cherokee Purple' naturally grow much larger than cherry or determinate bush types, which are bred to stay small.

The biggest mistake home growers make is planting too late in the season. A large tomato needs 75 to 90 days from transplant to full size, and another 20 to 30 days to ripen. If you plant in late May in a zone where frost arrives in September, you won't have time. Start seeds indoors 6 to 8 weeks before your last spring frost, or buy transplants early enough that you can set them out as soon as soil warms to 60°F.

Key Takeaways

  • Choose large-fruited varieties like beefsteak or heirloom types; cherry and bush varieties are bred to stay small no matter what you do.
  • Water deeply and consistently—aim for 1 to 2 inches per week from rain or irrigation, and water the soil, not the leaves, to prevent disease.
  • Feed every two to three weeks with a balanced fertilizer once flowers appear, then switch to lower nitrogen after fruit sets to push size rather than foliage.
  • Prune suckers (shoots that grow between the main stem and branches) on indeterminate varieties to direct energy into fewer, larger fruits.
  • Plant early enough that your tomatoes have 90 to 120 days to grow and ripen before the first frost in your area.

Water deeply and often, but not every day

Large tomatoes are mostly water—a 1-pound tomato is about 95 percent water by weight. Inconsistent watering is the single biggest reason tomatoes stay small or crack. The goal is steady moisture in the soil, not wet soil and not dry soil.

Water deeply once or twice a week rather than a little bit every day. Deep watering encourages roots to grow down into the soil where they're protected from heat and drought. Shallow daily watering keeps roots near the surface, where they dry out fast and can't support large fruit. Aim for 1 to 2 inches of water per week from rain or irrigation combined. In hot weather or sandy soil, you may need to water twice a week; in cool weather or clay soil, once a week may be enough.

Water the soil at the base of the plant, not the leaves. Wet foliage invites fungal diseases like early blight and septoria leaf spot, which kill leaves and stop the plant from feeding the fruit. Use a soaker hose, drip line, or a watering can held low to the ground. If you must overhead-water, do it early in the morning so leaves dry quickly.

Feed for growth, then for fruit

A tomato plant needs nitrogen to build leaves and stems, but too much nitrogen makes it grow all foliage and few fruits. Once flowers appear, shift to a fertilizer lower in nitrogen and higher in phosphorus and potassium, which push flowering and fruit size.

Start feeding two weeks after transplanting with a balanced fertilizer—something like 10-10-10 or 5-5-5. Feed every two to three weeks until the first flowers open. Once flowers appear, switch to a fertilizer with less nitrogen, such as 5-10-10 or 2-8-8, and keep feeding every two to three weeks through the growing season. Tomato-specific fertilizers are formulated this way and take the guesswork out.

You can also use compost or aged manure worked into the soil before planting, which releases nutrients slowly over the season. Add a 2-inch layer to the planting hole and mix it into the top 6 inches of soil. This won't give you the same control as liquid fertilizer, but it's reliable and won't burn roots if you overdo it.

Prune suckers on indeterminate varieties

Indeterminate tomatoes (the tall, vining types that keep growing all season) produce shoots called suckers where branches meet the main stem. These suckers grow into full branches if left alone, which spreads the plant's energy across many stems and many small fruits instead of fewer large ones.

Pinch or cut off suckers when they're small—1 to 2 inches long—so the plant doesn't waste energy growing them. Leave the main stem and the primary branches, and remove everything that sprouts between them. Do this every week or two during the growing season. Determinate (bush) varieties don't need this pruning because they're bred to stay compact and produce most of their fruit at once.

You can also remove some of the lower leaves once the plant is 2 to 3 feet tall. This improves air flow, reduces disease, and lets the plant put more energy into fruit instead of supporting extra foliage. Stop removing leaves once fruit is actively ripening, because leaves feed the ripening process.

Choose the right varieties from the start

Variety choice determines your ceiling for size. A cherry tomato will never weigh more than an ounce or two, no matter how well you grow it. Beefsteak varieties like 'Brandywine', 'Mortgage Lifter', and 'Big Beef' regularly reach 1 pound or more. Heirloom types like 'Cherokee Purple', 'Striped German', and 'Black Krim' also grow large, though they're often less disease-resistant than modern hybrids.

If you live in a short-season area (frost arrives before September), choose a large variety that matures in 70 to 80 days, not 90 days. 'Early Girl' and 'Stupice' are smaller but faster. You can also start with transplants instead of seeds to gain two to three weeks, which can be the difference between ripe fruit and green tomatoes when frost hits.

Support the weight as fruit grows

A tomato plant bearing several 1-pound fruits needs sturdy support. The weight will bend or break branches, and fruit touching the ground rots or gets eaten by pests. Use a cage at least 5 to 6 feet tall, or tie the main stem to a stake with soft ties (old cloth strips work well) every 12 inches as the plant grows.

As individual fruits grow large, you can tie them individually to the cage or stake with soft ties or pantyhose strips, which won't cut into the stem. This keeps the fruit from pulling the branch down and breaking it, and keeps the fruit off the soil.

Harvest at the right stage to maximize size

Large tomatoes take time to ripen. Pick them when they're fully colored but still slightly soft to the touch—this is the "breaker stage," when the first blush of color appears. A tomato picked at this stage will continue to ripen off the vine and will be sweeter and larger than one picked fully hard.

If frost is coming and you have green tomatoes still on the vine, pick them and ripen them indoors on a windowsill or in a paper bag with a ripe banana or apple (which release ethylene gas and speed ripening). They won't grow any larger off the vine, but they'll ripen to full color and flavor.

Frequently Asked Questions

How big can tomatoes actually get?

Beefsteak and heirloom varieties commonly reach 1 to 2 pounds. The world record is over 3 pounds, but that requires ideal conditions and a variety bred for extreme size. Most home growers see 12 to 24 ounces with good technique and a good variety.

Should I remove flowers to make fewer, bigger tomatoes?

Removing some flower clusters early in the season can direct energy into fewer fruits, making them larger. Pinch off the smallest or most crowded clusters when they first appear, leaving the strongest ones. Don't remove flowers once fruit has already set, because you'll just reduce your total harvest.

What if my tomatoes are splitting or cracking?

Splitting happens when watering is inconsistent—usually a dry spell followed by heavy rain or watering. Keep soil moisture steady, and mulch around the plant with 2 to 3 inches of straw or wood chips to buffer moisture swings. Once a tomato starts to crack, it won't heal, but consistent watering will prevent it on new fruit.

Can I grow huge tomatoes in a container?

Yes, but the container must be large—at least 5 gallons, ideally 10 or more. Larger containers hold more soil and moisture, which large tomatoes need. Use quality potting soil, not garden soil, and feed more often because water drains through containers faster than ground soil.

Why are my tomatoes still small even though I'm doing everything right?

Check your variety first—some are just bred small. If the variety should grow large, the most common causes are too much nitrogen (which makes foliage instead of fruit), inconsistent watering, or not enough time before frost. You can't fix time mid-season, but you can adjust water and fertilizer for next year.