Tomatoes need sun, consistent water, and soil that drains well to produce a real harvest
Tomato plants fail most often because they don't get enough light, the soil stays too wet, or the plant runs out of nutrients mid-season. A tomato needs at least six to eight hours of direct sunlight every day—more is better. The soil should feel damp when you squeeze it, not soggy or bone-dry. And once the plant starts flowering, it needs regular feeding because fruit production drains nutrients fast.
The good news: tomatoes are forgiving. If you get these three things roughly right—light, water, and feeding—you will get fruit. You don't need special equipment or a perfect setup. A pot on a sunny patio works. A patch in the backyard works. The plant itself does most of the work.
Key Takeaways
- Tomatoes need six to eight hours of direct sun daily; less light means fewer flowers and fruit.
- Water deeply and less often rather than a little every day, so the soil drains between waterings and roots don't rot.
- Feed the plant every two to three weeks once flowers appear, using a fertilizer higher in phosphorus and potassium than nitrogen.
- Prune suckers (shoots that grow between the main stem and branches) on indeterminate varieties to direct energy into fruit instead of leaves.
- Pick fruit when it is fully colored but still slightly soft; it will ripen fully off the vine and taste better than fruit picked green.
Choosing between determinate and indeterminate varieties
Determinate tomatoes grow to a fixed size, flower all at once, and produce most of their fruit in a short window—usually four to six weeks. They are compact, need less pruning, and work well in pots. Cherry tomatoes like 'Tiny Tim' and paste tomatoes like 'San Marzano' are often determinate. You get a big harvest fast, then the plant slows down.
Indeterminate tomatoes keep growing taller all season, flower continuously, and produce fruit from mid-summer until frost kills the plant. Slicing tomatoes like 'Brandywine' and 'Cherokee Purple' are usually indeterminate. They need staking or caging, pruning to stay manageable, and more space—but they produce for months.
For a first-time grower, determinate is simpler. You plant it, stake it lightly, and harvest a lot of fruit at once. If you want tomatoes all summer, go indeterminate and plan to prune and support it.
Planting in soil that drains and feeding from the start
Tomatoes rot if water sits around the roots. Use soil that drains well—a mix of compost, peat moss or coco coir, and perlite or coarse sand works. If you are planting in the ground, dig a hole, mix in compost, and plant deep: bury the stem up to the first true leaves. Roots will form all along the buried stem, making the plant stronger.
At planting time, mix a balanced fertilizer into the soil—something like 10-10-10 (nitrogen-phosphorus-potassium). Once the plant flowers, switch to a fertilizer higher in phosphorus and potassium, like 5-10-10 or 10-20-20. Too much nitrogen makes the plant grow leaves instead of fruit. Feed every two to three weeks once flowers appear, following the package rate.
If you are planting in a pot, use a pot at least 12 inches across for determinate varieties and 18 to 24 inches for indeterminate. Larger pots hold more soil and water, so the plant is less stressed between waterings.
Watering deeply and less often prevents most problems
The biggest mistake is watering a little bit every day. This keeps the top of the soil wet while the deeper roots stay dry, and it invites fungal disease. Instead, water deeply once or twice a week so the soil is damp all the way down, then let it dry out slightly before watering again.
In hot weather, this might mean watering every three to four days. In cool weather, every seven to ten days. Stick your finger two inches into the soil: if it feels dry, water. If it feels damp, wait. A soaker hose or drip line is better than overhead watering because it keeps the leaves dry, which stops fungal spots and blights from taking hold.
Mulch around the base of the plant with two to three inches of compost or straw. Mulch keeps the soil temperature steady, reduces water loss, and prevents soil from splashing onto the leaves during rain or watering.
Staking and pruning indeterminate varieties
Indeterminate tomatoes grow tall and heavy with fruit. Without support, the stem breaks or the plant sprawls on the ground. Drive a stake or cage into the soil at planting time, before the roots spread. A stake should be at least five to six feet tall; a cage should be sturdy and at least four feet tall. Tie the main stem loosely to the stake with soft ties or strips of cloth as it grows, every 12 inches or so.
Indeterminate plants also grow suckers—shoots that sprout in the angle between the main stem and a branch. These suck energy away from fruit production. Pinch or cut them off when they are small. Leave the main stem and the main branches; remove everything else. This sounds harsh, but it works: a pruned plant produces bigger fruit and more of it.
Determinate varieties don't need much pruning. A light cage or stake is enough to keep the fruit off the ground.
Recognizing and managing common problems
Blossom end rot shows up as a dark, sunken spot on the bottom of the fruit. It is caused by uneven watering, usually a dry spell followed by heavy watering. The plant can't move calcium to the fruit fast enough. Keep the soil consistently damp, not wet and dry in turns. Mulch helps. Once it appears on a fruit, that fruit is done, but new fruit will be fine if you steady the watering.
Early blight is a fungal disease that starts as brown spots with rings on the lower leaves, then spreads upward. Remove the affected leaves, improve air flow by pruning lower branches, and water at the soil level, not overhead. If it spreads fast, a fungicide with copper or sulfur can slow it. Determinate varieties are more resistant than indeterminate ones.
Sunscald is a pale, papery spot on fruit exposed to intense afternoon sun. It is not a disease. Prune carefully so fruit has some leaf cover in the hottest part of the day, but not so much that the plant can't ripen fruit.
Insects like hornworms and whiteflies can damage leaves and fruit, but they rarely kill the plant. Hand-pick large insects. For heavy infestations, neem oil or insecticidal soap work on soft-bodied insects like whiteflies.
Harvesting at the right stage for best flavor
Pick tomatoes when they are fully colored but still slightly soft to the touch. A ripe tomato gives a little when you squeeze it gently. Fruit picked at this stage will finish ripening off the vine over a few days and will taste better than fruit picked fully soft, which bruises easily.
If frost is coming and you have green tomatoes still on the plant, pick them and set them on a windowsill or in a paper bag. They will ripen indoors over one to three weeks. Tomatoes picked fully green won't ripen well, but tomatoes picked at the "breaker stage"—when the first blush of color appears—will ripen to full flavor.
Once you pick a tomato, don't refrigerate it unless it is already overripe. Cold breaks down the flavor compounds. Keep it on the counter at room temperature.
Frequently Asked Questions
Can I grow tomatoes in a pot indoors under a grow light?
Yes, but the plant needs a strong light source—at least 12 to 16 hours a day from a light positioned close to the leaves. A regular household bulb won't work; you need a fluorescent or LED grow light. Indoors, you also need to hand-pollinate the flowers by gently shaking the plant when it flowers, because there are no bees to do it. Determinate varieties work better indoors because they stay compact.
Why are my tomato flowers dropping off without making fruit?
Flowers drop when the plant is stressed—usually from inconsistent watering, too much nitrogen, or temperatures below 55°F or above 90°F at night. Steady the watering, switch to a lower-nitrogen fertilizer, and wait for the temperature to stabilize. The plant will flower again once conditions improve.
How do I know when to stop pruning suckers?
Stop pruning suckers about four to six weeks before your first expected frost. At that point, let the plant grow freely so it can ripen all the fruit it has already set. If you keep pruning late in the season, you remove flowers that won't have time to mature into fruit.
What is the difference between heirloom and hybrid tomatoes?
Heirloom tomatoes are open-pollinated varieties that have been grown for decades or longer; they taste excellent but are often less disease-resistant and less productive than hybrids. Hybrid tomatoes are bred for disease resistance, productivity, and shelf life, but they don't breed true—seeds from a hybrid won't grow the same plant. Both work fine for home growing; choose based on flavor and disease resistance in your area.
Can I save seeds from my tomatoes to plant next year?
Yes, but only from heirloom or open-pollinated varieties. Scoop the seeds and gel into a jar, add a little water, and let them ferment for two to three days to remove the gel coating. Rinse, dry on a plate for two weeks, and store in a cool, dry place. Seeds from hybrid tomatoes won't grow plants identical to the parent, so saving them is not worth the effort.