Water deeply and consistently, not daily
The single most common mistake is watering tomato plants a little bit every day. This keeps the soil surface wet but the roots dry, and it encourages fungal disease. Instead, water deeply two or three times a week—enough that water runs out the drainage holes—then let the soil dry out slightly before watering again.
The exact schedule depends on your climate, pot size, and whether you're growing in ground or containers. In hot weather, container plants may need water every two days. In cool weather or after rain, you might go five days. The real test is the soil itself: stick your finger two inches down. If it feels dry, water. If it feels moist, wait another day or two.
Water at the base of the plant, not on the leaves. Wet foliage invites early blight and powdery mildew. A soaker hose or drip line works better than overhead watering, but a regular hose pointed at the soil line is fine too.
Key Takeaways
- Water deeply two to three times a week so the soil dries slightly between waterings, rather than watering a little every day.
- Tomato plants need at least six to eight hours of direct sunlight daily, and eight to ten hours is better for fruit production.
- Prune suckers (shoots that grow between the main stem and branches) on indeterminate varieties to direct energy toward fruit instead of leaves.
- Support the plant with a cage or stake early, before the stem gets thick and brittle, to prevent breaking under the weight of fruit.
- Feed every two to three weeks once flowers appear, using a fertilizer lower in nitrogen and higher in phosphorus and potassium.
Give tomato plants at least six to eight hours of direct sun
Tomatoes are sun-hungry plants. Six to eight hours of direct sunlight is the minimum for survival and fruit production. Eight to ten hours is better. If your plant gets less than six hours, it will grow tall and spindly, produce fewer flowers, and the fruit that does form will ripen slowly and taste bland.
Direct sun means unobstructed sunlight, not dappled shade under a tree. Morning sun is especially valuable because it dries dew off the leaves and reduces fungal disease. If you're growing in containers, move them to follow the sun throughout the day if your garden is partially shaded.
In very hot climates (above 95°F regularly), afternoon shade during the hottest part of summer can actually help—intense heat can cause blossom end rot and reduce fruit set. But this is the exception. Most growers need to maximize sun exposure.
Support the plant early with a cage or stake
A tomato plant loaded with fruit becomes heavy and brittle. The stem snaps, the plant collapses, and you lose the crop. Install support within the first two to three weeks of planting, before the stem thickens and becomes difficult to tie without damaging it.
A cage works well for determinate varieties (bush types that grow to a fixed size). Push it firmly into the ground so it doesn't tip over in wind. For indeterminate varieties (vining types that grow all season), a single stake or a string trellis system is more practical—cages become too small as the plant grows.
Tie the stem loosely to the support with soft material like cloth strips or plant tape. Tight ties cut off circulation. Check the ties every week or two and loosen them as the stem thickens. Never use wire or string that doesn't stretch.
Prune suckers on indeterminate varieties to focus growth
On indeterminate tomatoes (the tall, vining kinds), small shoots called suckers grow in the angle between the main stem and each branch. These aren't leaves—they're potential new stems. If left alone, they become full branches that produce leaves but fewer fruit, and they shade the lower part of the plant.
Pinch or cut off these suckers when they're small, before they get woody. On a determinate (bush) tomato, you can leave them alone—the plant is genetically programmed to stop growing at a certain height anyway. But on an indeterminate, removing suckers directs the plant's energy into fruit production instead of foliage.
Also remove leaves that touch the ground or are heavily shaded by upper growth. These lower leaves are the first to get disease, and they don't contribute much to photosynthesis anyway. Removing them improves air circulation and reduces fungal problems.
Feed with the right balance once flowers appear
Tomato plants need nitrogen early to build leaves and stems, but too much nitrogen late in the season produces lots of foliage and few flowers. Once the plant starts flowering, switch to a fertilizer lower in nitrogen and higher in phosphorus and potassium. A typical ratio for fruiting is something like 5-10-10 or 2-7-7.
Feed every two to three weeks during the growing season. You can use a granular fertilizer worked into the soil, a liquid fertilizer mixed with water, or a slow-release pellet added at planting time. Follow the package directions for amounts—more fertilizer doesn't mean more fruit, and excess nitrogen can actually reduce flowering.
If the leaves turn yellow while the plant is still producing, that's often a sign of nitrogen deficiency. If the plant is all leaves and no flowers, you've probably given too much nitrogen. Adjust based on what you see.
Watch for common pests and diseases
The most common tomato problems are fungal diseases like early blight (brown spots with concentric rings on lower leaves) and powdery mildew (white coating on leaves). Both spread in wet conditions. Prevent them by watering at the base, not overhead; removing lower leaves; and spacing plants so air flows between them.
Hornworms are large green caterpillars that can strip a plant bare. Check the undersides of leaves and pick them off by hand. Whiteflies and spider mites are tiny pests that cause yellowing and stippling. A strong spray of water from the hose can knock them off, or use insecticidal soap if the problem is severe.
Blossom end rot—a dark, sunken spot on the bottom of the fruit—is caused by inconsistent watering and calcium deficiency. It's prevented by watering steadily and mulching to keep soil moisture even. Once it appears on a fruit, that fruit can't be saved, but consistent watering will prevent it on new fruit.
Mulch to regulate soil moisture and temperature
A two- to three-inch layer of mulch around the base of the plant keeps soil temperature steady, reduces water loss, and prevents soil from splashing onto leaves (which spreads disease). Use straw, shredded leaves, or wood chips. Keep the mulch a few inches away from the stem so it doesn't trap moisture against the plant.
Mulch also reduces the number of times you need to water and makes watering more effective—water soaks in instead of running off. In hot climates, mulch keeps roots cooler. In cool climates, it keeps soil warmer. Either way, it reduces stress on the plant.
Frequently Asked Questions
How often should I water tomato plants in containers versus in the ground?
Container plants dry out faster and usually need water every two to three days in warm weather, sometimes daily in extreme heat. In-ground plants have access to deeper soil moisture and typically need water two to three times a week. The real guide is the soil itself—stick your finger in and water when the top two inches feel dry.
Can I save a tomato plant that's turning yellow?
Yellow leaves on the lower plant are usually normal as the plant matures and shades itself—just remove them. Yellow leaves throughout the plant often means nitrogen deficiency, which you can fix by feeding with a balanced or nitrogen-rich fertilizer. Yellow leaves with brown spots usually mean early blight, which spreads; remove the affected leaves and improve air circulation by pruning.
What's the difference between determinate and indeterminate tomatoes, and does it matter for care?
Determinate tomatoes grow to a fixed size (usually three to four feet) and produce most of their fruit at once. Indeterminate tomatoes grow all season and produce fruit continuously until frost. Indeterminate plants need more pruning, taller stakes, and more frequent feeding. Determinate plants are simpler—you can leave suckers on and use a cage for support.
Should I remove flowers to get bigger fruit?
No. Removing flowers reduces your total harvest. The plant naturally produces more flowers than it can support, and it will drop some on its own if stressed. Let the plant decide which fruit to keep. If you want larger individual tomatoes, thin fruit clusters to one or two per cluster once they're marble-sized, but don't remove flowers.
Why are my tomatoes cracking or splitting?
Cracking happens when the fruit absorbs water too quickly after a dry period—usually after heavy rain or a sudden increase in watering. Prevent it by watering consistently so soil moisture stays even. Mulch helps regulate moisture. Some varieties are more prone to cracking than others, so variety choice matters too.