Plant tomatoes in spring after the last frost, in a spot that gets at least six to eight hours of direct sun each day

Tomatoes need warmth and light to grow well. Wait until nighttime temperatures stay above 50°F before moving seedlings outdoors or planting seeds directly in the ground — tomato plants will sit dormant or rot if the soil is too cold. Choose a location where the plants will receive sun from morning through afternoon; less light means fewer tomatoes and a higher risk of disease.

If you are starting from seed indoors, plant them six to eight weeks before your last spring frost date. Fill a seed tray with seed-starting mix, press seeds about a quarter-inch deep, and keep the soil moist (not soggy) under grow lights or on a sunny windowsill. Seedlings will sprout in five to ten days and are ready to move outside once they have two sets of true leaves — the second set that looks like actual tomato leaves, not the smooth oval cotyledons that emerge first.

If you are planting seedlings or transplants from a nursery, dig a hole slightly deeper than the root ball and bury the stem up to the lowest set of leaves. Tomato roots will form all along the buried stem, creating a stronger plant. Space plants 24 to 36 inches apart so air can flow between them.

Key Takeaways

  • Plant tomatoes outdoors only after nighttime temperatures stay above 50°F, in a spot with six to eight hours of direct sun.
  • Bury the stem deeper than the root ball when transplanting; roots will form along the buried portion and strengthen the plant.
  • Water deeply at the base of the plant once or twice a week, depending on heat and rainfall, rather than sprinkling the leaves.
  • Support the plant with a cage or stake early on, before it becomes heavy with fruit and branches break.
  • Pinch off the bottom leaves once the plant is established to reduce disease and improve air circulation around the fruit.

Water at the soil level, not the leaves, and keep the soil consistently moist

Tomatoes need steady moisture to grow fruit without cracking or developing blossom-end rot (a dark, sunken spot on the bottom of the fruit). Water deeply at the base of the plant once or twice a week, delivering about one to two inches of water per week depending on heat and rainfall. In hot weather or sandy soil, you may need to water more often; in cool, wet weather, less.

Water in the early morning so any moisture on the leaves can dry quickly. Wet foliage invites fungal diseases like early blight and powdery mildew. If you water in the evening, the leaves stay damp overnight and disease spreads faster. A soaker hose or drip line delivers water straight to the soil and keeps the leaves dry — this is the best method if you have the space to set it up.

Let the top inch of soil dry out between waterings, but do not let the plant wilt. Inconsistent watering — dry one week, soaked the next — causes the fruit to crack as it absorbs water unevenly. If you live in a very hot climate or your soil drains quickly, mulch around the base with two to three inches of straw or wood chips to hold moisture and keep the soil cooler.

Support the plant with a cage or stake to prevent branches from breaking

Tomato plants grow heavy once fruit sets, and branches will snap under the weight without support. Install a cage or stake early — within two to three weeks of planting — before the plant is large and you risk damaging roots by driving a stake into the ground later.

A tomato cage is a wire frame you slip over the plant when it is small. It works well for determinate (bush) varieties that grow to a fixed height and stop. For indeterminate (vining) varieties that grow taller throughout the season, a cage may not be tall enough by mid-summer.

A stake — a wooden pole, bamboo rod, or metal rod driven into the ground — works for any variety. Drive it at least eight inches into the soil so it does not tip over in wind. As the plant grows, tie the main stem loosely to the stake with soft ties (strips of cloth, garden tape, or commercial plant ties) every eight to twelve inches. Tie in a figure-eight pattern so the tie crosses between the stake and stem, leaving room for the stem to thicken without cutting off circulation.

Fertilize every two to three weeks once flowers appear

Tomatoes are heavy feeders and need nutrients throughout the growing season. Before planting, work compost or aged manure into the soil to give the plant a nutrient base. Once the plant flowers and begins setting fruit, feed it every two to three weeks with a balanced fertilizer or one higher in phosphorus and potassium (the second and third numbers on a fertilizer label) to encourage fruiting rather than leaf growth.

You can use a liquid fertilizer diluted in water, a granular fertilizer sprinkled around the base and watered in, or a slow-release fertilizer pellet mixed into the soil at planting. Follow the label instructions for the amount — too much fertilizer, especially nitrogen, produces lots of leaves but few tomatoes. If you see yellowing leaves on the lower plant, the plant may need more nitrogen; if leaves are purple-tinged, it may need phosphorus. A soil test from your local extension office will tell you exactly what your soil is missing, but most garden soils benefit from a balanced approach.

Prune suckers and lower leaves to improve air flow and reduce disease

A sucker is a shoot that grows in the angle between the main stem and a branch. On indeterminate varieties, suckers grow into full branches that produce fruit but also shade the plant and trap moisture. Pinch off suckers when they are small — just an inch or two long — by snapping them off with your fingers. On determinate varieties, you can leave some suckers since the plant has a fixed size and stops growing.

Once the plant is three to four feet tall and has set its first fruit, pinch off the bottom six to eight inches of leaves. These lower leaves are closest to the soil, where fungal spores live, and removing them reduces the chance of early blight and other soil-borne diseases. Continue removing lower leaves as the plant grows, always leaving at least the top third of the plant with foliage to power fruit development.

Prune on a dry day and use clean pruners or scissors to avoid spreading disease. If you are moving between plants, wipe the blade with a cloth dampened in rubbing alcohol or a 10 percent bleach solution (one part bleach to nine parts water).

Harvest tomatoes when they reach full color but are still slightly firm

Tomatoes ripen from the inside out, so a fully colored tomato is ripe and ready to pick. Gently twist and lift the fruit, or use pruners to cut the stem if it does not come away easily. A ripe tomato should yield slightly to gentle pressure but not be mushy.

If frost is coming and you have green tomatoes still on the vine, pick them and place them in a paper bag with a ripe banana or apple. The ethylene gas from the fruit speeds ripening. Keep the bag at room temperature — tomatoes ripen faster in warmth, around 68 to 77°F. Do not refrigerate unripe tomatoes; cold slows ripening and damages flavor.

Once you have harvested the main crop, you can leave the plant in the ground to produce a second, smaller flush of fruit in late summer and early fall. If disease is spreading or the plant looks exhausted, pull it out and compost it (not diseased material — discard that in the trash).

Common problems and how to prevent them

Blossom-end rot appears as a dark, sunken spot on the bottom of the fruit and is caused by calcium deficiency linked to inconsistent watering. Water deeply and regularly, mulch to keep moisture even, and avoid overhead watering that washes calcium away. Once fruit shows the spot, it cannot be fixed, but consistent watering prevents it on new fruit.

Early blight shows as brown spots with concentric rings on lower leaves and spreads upward. Remove affected leaves, improve air circulation by pruning, water only at the base, and mulch to prevent soil splash. If the disease is severe, a fungicide containing copper or chlorothalonil can slow it — follow label instructions and stop spraying two weeks before harvest.

Cracked fruit happens when the plant receives a heavy rain or watering after a dry period. The fruit absorbs water too fast and the skin splits. Mulch and water consistently to prevent this. Varieties like 'San Marzano' and 'Amish Paste' are less prone to cracking than large slicing types.

Few or no flowers usually means too much nitrogen (the plant is all leaves) or not enough light. Cut back on fertilizer, may support the plant gets at least six hours of direct sun, and be patient — some varieties flower later than others.

Frequently Asked Questions

Can I grow tomatoes in a pot?

Yes. Use a pot at least five gallons for determinate varieties and ten gallons for indeterminate types. Fill it with potting mix (not garden soil), water more often since containers dry faster, and fertilize every two weeks. Pots warm up faster in spring and cool down faster in fall, so you may get an earlier or shorter harvest than in-ground plants.

How do I know if my tomato plant needs more water?

Stick your finger two inches into the soil. If it feels dry, water deeply. If it feels moist, wait another day or two. Wilting leaves during the hottest part of the day may recover by evening, but consistent wilting means the plant needs water. Overwatering is more common than underwatering and causes root rot and disease.

What is the difference between determinate and indeterminate tomatoes?

Determinate varieties grow to a fixed height (usually three to four feet), flower all at once, and produce most of their fruit in a short window — good for canning. Indeterminate varieties grow continuously throughout the season, flower and fruit over months, and can reach six feet or taller — good for fresh eating. Check the seed packet or plant label to know which type you have.

Why are my tomato flowers falling off without making fruit?

Flowers drop when temperatures are too hot (above 90°F at night), too cold (below 55°F), or when the plant is stressed by drought or too much nitrogen. Consistent watering, shade cloth in extreme heat, and balanced fertilizer help. Some flowers naturally drop; the plant will produce more.

Can I save seeds from my tomatoes?

Yes, but only from heirloom or open-pollinated varieties. Hybrid tomatoes (marked F1 on the label) will not produce seeds that grow into the same plant. Scoop seeds and gel into a jar, add a little water, let them ferment for two to three days, rinse thoroughly, and dry on a plate for two weeks before storing in a cool, dry place.