Water deeply and consistently, not daily
Tomato plants need steady moisture, but daily shallow watering weakens them. Instead, water deeply two or three times a week so the soil stays moist 6 to 8 inches down—deep enough that roots reach for water rather than staying near the surface. Stick your finger into the soil; if it feels dry past the first knuckle, water. If it still feels wet, wait another day.
Water at the base of the plant in early morning, not on the leaves. Wet foliage invites fungal diseases like early blight and septoria leaf spot, which spread fast in humid conditions. A soaker hose or drip line does this automatically and saves water. If you use a sprinkler or hand-water overhead, do it before 9 a.m. so leaves dry quickly.
Container tomatoes dry out faster than garden soil, so check them daily. A 5-gallon pot may need water every other day in hot weather. Mulch around the base with 2 to 3 inches of straw or wood chips to keep soil temperature steady and reduce how often you water.
Key Takeaways
- Water deeply two or three times a week so soil stays moist 6 to 8 inches down, rather than watering a little bit every day.
- Water at the base of the plant in early morning to keep leaves dry and prevent fungal diseases.
- Prune suckers (shoots that grow between the main stem and branches) on indeterminate varieties to direct energy into fruit instead of foliage.
- Feed every two to three weeks with a balanced fertilizer once the plant flowers, or use a slow-release fertilizer at planting time.
- Remove leaves below the first fruit cluster as the plant grows to improve air flow and reduce disease pressure.
Prune suckers on indeterminate varieties to focus growth on fruit
Indeterminate tomatoes (the tall, vining kinds that grow all season) produce suckers—small shoots that sprout where a branch meets the main stem. These steal energy from fruit production. Pinch them off when they are small, using your fingers or pruning shears. Determinate varieties (the bushy, compact kinds) produce most of their fruit at once and need less pruning, so focus on indeterminate plants.
Start pruning when the plant is 12 to 18 inches tall. Check every few days during the growing season and remove suckers before they get woody. If you wait until they are thick, the plant wastes energy healing the wound. A clean pinch with your thumb and forefinger is faster and causes less stress than cutting with shears.
Do not remove all the leaves—they feed the plant through photosynthesis. Only remove suckers and, later in the season, leaves that touch the ground or show disease.
Feed regularly once flowers appear, or use slow-release fertilizer at planting
Tomatoes are heavy feeders. If you mixed compost or aged manure into the soil before planting, the plant will have nutrients for the first few weeks. Once flowers appear, start feeding every two to three weeks with a balanced fertilizer (one with equal parts nitrogen, phosphorus, and potassium—look for numbers like 10-10-10 on the label).
Alternatively, mix a slow-release fertilizer into the soil at planting time. These pellets break down over months and feed the plant steadily without extra work. Follow the package directions for how much to use based on your pot or bed size. Slow-release fertilizers are especially useful for container tomatoes, where frequent watering can wash nutrients away.
Avoid high-nitrogen fertilizers once the plant flowers—they push leafy growth at the expense of fruit. If your tomato plant is all leaves and few flowers, you are feeding too much nitrogen or the plant is in too much shade.
Remove lower leaves and improve air circulation
As your tomato plant grows, remove leaves that touch the soil or hang below the first fruit cluster. These leaves are the first to catch fungal spores from soil splash and disease spreads upward from there. Removing them also opens up the base of the plant so air flows through, drying leaves faster after rain or watering.
Space plants 24 to 36 inches apart so they do not crowd each other. Crowded plants stay wet longer and diseases spread faster. If you are growing in containers, do not cluster pots so tightly that leaves touch between plants. Thin the canopy by removing some of the lower branches as the plant grows taller—this sounds harsh, but it prevents disease and does not reduce your harvest.
Watch for common pests and diseases early
Check the undersides of leaves once a week for spider mites (tiny specks that make leaves look dusty and yellowed) and hornworms (large green caterpillars that eat whole sections of leaves). Hornworms are straightforward to spot and hand-pick. Spider mites thrive in hot, dry conditions; misting the plant with water or spraying the undersides of leaves with a hose can knock them off and slow their spread.
Early blight shows as brown spots with concentric rings on lower leaves, usually starting in mid-summer. Septoria leaf spot looks like small circular spots with dark edges and gray centers. Both spread in wet conditions. Remove affected leaves when ready and throw them in the trash, not the compost pile. Do not touch other plants after handling diseased leaves.
If disease spreads despite your efforts, ask your local cooperative extension office (search "[your state] cooperative extension" online) whether a fungicide is recommended for your area. Many gardeners have success with sulfur or copper-based products, but timing and process matter—extension staff can tell you when to spray.
Support the plant and manage fruit load as it grows
Tomato plants get heavy once fruit sets. Install a cage or stake at planting time, before roots spread—driving a stake through an established root system damages the plant. Cages work for determinate varieties; indeterminate plants often outgrow cages and need stakes or string trellising instead. Tie the main stem loosely to the support with soft material like cloth strips or plant tape so the stem can expand as it thickens.
In mid-to-late summer, pinch off new flower clusters that appear after your region's first frost date (search "[your city] first frost date" to find yours). Flowers that appear too late will not have time to ripen fruit before cold arrives, and the plant will waste energy on them instead of ripening the tomatoes already on the vine.
Harvest ripe fruit and manage end-of-season decline
Pick tomatoes when they are fully colored but still slightly soft—they will finish ripening off the vine and taste better than fruit picked rock-hard. Leaving ripe fruit on the plant signals the plant to slow production, so harvest regularly to keep flowers coming.
As temperatures drop in fall, growth slows and disease pressure increases. Once nighttime temperatures drop below 55°F, the plant stops setting new fruit. At that point, remove the plant and compost it (or throw it away if it has disease). Do not leave it in the garden over winter—pests and diseases overwinter in plant debris.
Frequently Asked Questions
Why are my tomato leaves turning yellow?
Yellow leaves usually mean either too much water, too little nitrogen, or disease. Check the soil—if it is soggy, water less often. If the yellowing starts on lower leaves and moves upward, it is likely early blight or a nutrient issue; remove the affected leaves and feed the plant. If the whole plant is pale yellow, it may need nitrogen.
Can I grow tomatoes in a pot on a patio?
Yes. Use a pot at least 5 gallons for determinate varieties and 10 gallons for indeterminate types. Fill it with potting soil (not garden soil), water daily or every other day depending on heat, and feed every two weeks once flowers appear. Container tomatoes need at least 6 to 8 hours of direct sun daily.
What causes blossom end rot, the dark sunken spot on the bottom of the fruit?
Blossom end rot is caused by inconsistent watering, usually a dry spell followed by heavy watering. The plant cannot move calcium to the developing fruit fast enough. Water deeply and steadily, and mulch to keep soil moisture even. Once fruit shows the spot, it cannot be fixed, but consistent watering prevents it on new fruit.
How do I know when to stop watering in fall?
Once nighttime temperatures drop below 55°F regularly, the plant stops ripening new fruit and growth slows. You can reduce watering at that point, but do not let the soil dry out completely—the plant still needs moisture to ripen the fruit already on the vine. Pull the plant once the first frost arrives or fruit stops ripening.
Should I use fertilizer stakes or liquid fertilizer?
Both work. Fertilizer stakes are slow-release and require no mixing or measuring, so they are easier for busy gardeners. Liquid fertilizer gives you more control over timing and strength, so you can adjust if the plant looks hungry. For container tomatoes, liquid fertilizer is often better because frequent watering can leach nutrients from slow-release products.