Tomato

Choosing & planning

What is tomato and where does it grow best?

Tomato (Solanum lycopersicum) is a warm-season annual originating in South America (Peru, Bolivia, Ecuador), brought to Europe by Spanish explorers in the late 1400s. It grows best in full sun with warm temperatures and can be grown as an annual across USDA zones 5–11; spring and fall frosts limit the outdoor season in most regions. It survives as a short-lived perennial only in zones 10–12.

What are the main types of tomato, and how do they differ?

Tomatoes divide into two growth habits: determinate (bush) varieties grow to a fixed height, set all fruit in a concentrated 2–3 week window, and are easier to support; indeterminate (vining) varieties continue growing and producing until killed by frost. By fruit type they range from large beefsteak and slicing types to cherry, grape, and paste/Roma varieties, differing in size, flavor concentration, and best culinary use.

Which tomato varieties are recommended, and how do I choose one?

Choose based on intended use, climate, and days to maturity. Recommended options include Brandywine and Cherokee Purple (heirloom beefsteak), San Marzano (paste/sauce), Better Boy and Celebrity (standard red slicers), and Early Girl (short-season slicing). For Zone 3 or very short seasons, use 52–65 day varieties such as Stupice, Sub-Arctic Plenty, Siletz, or Early Girl.

What should I look for when buying tomato seeds or transplants?

Look for disease resistance indicated by letters after the variety name: V (Verticillium), F (Fusarium), N (nematodes), T (Tobacco mosaic virus), A (Alternaria/early blight), and TSWV (Tomato spotted wilt virus). Purchase certified, disease-free transplants whenever possible and match the variety’s days to maturity and growth habit (determinate or indeterminate) to your season and intended use.

Can I grow tomato in my climate or hardiness zone?

Tomatoes grow as annuals in USDA zones 5–11. Zone 3 gardeners can succeed by choosing 52–65 day varieties, starting indoors around April 13, and transplanting after June 1. In cool, foggy coastal climates, select varieties with 55–75 days to maturity and plant in the warmest available microclimate.

Can I grow tomato in containers or pots, and what size do they need?

Yes. Determinate varieties, which grow to about 3 feet tall, are the best choice for containers. Container tomatoes need watering once per day—sometimes twice in hot weather—because pots dry out faster than in-ground beds. Self-watering container systems help maintain the consistent moisture tomatoes require.

Can I grow tomato indoors or in a greenhouse?

Yes. Fresh-market tomatoes are commonly grown in high tunnels and greenhouses; in Pennsylvania, production in high tunnels can begin as early as June. In Indiana, high-tunnel production is widespread, but growers must watch for leaf mold, white mold, gray mold, and Tomato spotted wilt virus—which is transmitted by thrips and is particularly prevalent when tomatoes are grown alongside flower plugs.

How many tomato plants should I grow per person or household?

A few plants provide an adequate harvest for most families. Both University of Illinois Extension and University of Arkansas Extension make this consistent recommendation; the right number depends on the productivity of the chosen variety and how much you plan to preserve.

Starting from seed & propagation

Should I start tomato from seed or buy transplants?

Transplanting gives tomatoes the best start and is the standard approach. Starting from seed at home is worthwhile because it opens access to hundreds of varieties—such as Sun Gold, Amish Paste, and Moonglow—rarely available as transplants, and costs far less per plant once you have a basic setup.

When should I start tomato seeds indoors?

Start tomato seeds indoors 4–8 weeks before your average last frost date; most sources recommend 6–8 weeks. In Zone 5 (Wisconsin), with a mid-May last frost, that means mid-to-late March. Starting too early produces overgrown seedlings that are difficult to manage at transplant time.

How deep should I sow tomato seeds?

Sow seeds 1/8 to 1/4 inch deep in a sterile, soilless seed-starting mix, firm lightly, then moisten thoroughly. Never use garden soil or regular potting mix, which can drain poorly and harbor disease organisms.

What temperature do tomato seeds need to germinate?

A minimum soil temperature of 70°F is required for reliable germination; mid-80s°F is better in the earliest days. Place seed trays on a heat mat to maintain warmth; once seeds germinate, remove the heat mat to prevent seedlings from growing too rapidly.

How long do tomato seeds take to germinate?

Seeds germinate in 7–14 days when started indoors at proper temperatures. Early varieties may sprout in just a few days; 10 days is typical with consistent heat mat use.

Why are my tomato seedlings leggy or weak?

Insufficient light is the primary cause—seedlings on a windowsill stretch toward the sun and become tall and spindly. Grow seedlings under overhead LED or fluorescent grow lights rather than on a windowsill. Leaving the heat mat on too long after germination also causes seedlings to grow too rapidly and get spindly.

Site, soil & timing

How much sun does tomato need?

Tomatoes need a minimum of 6–8 hours of full sun per day; 8–10 hours is ideal. In shady or foggy gardens, plant in the spot that receives the most daily sun hours—even a container on a sunny patio can substitute for an in-ground bed.

What type of soil does tomato prefer?

Tomatoes grow in almost any moderately well-drained soil. A good supply of organic matter increases yield and reduces production problems. Fertile, well-drained soil is ideal.

What soil pH does tomato need?

Tomatoes prefer a soil pH of 6.0–6.8.

How should I prepare and amend the soil for tomato?

Incorporate a good amount of organic matter to increase yield and reduce production problems. Rotate tomatoes with non-solanaceous crops every three years; corn is an excellent rotation choice because it adds organic matter and does not harbor tomato pathogens. Avoid following tomatoes, potatoes, peppers, or eggplant with the same crops in the same ground.

When should I plant tomato outdoors?

Plant outdoors after the last frost date, when the soil is warm. Starting transplants 5–6 weeks before the frost-free date and setting them out after frost danger has passed is the recommended approach. In cool climates, be prepared to cover early-set plants overnight to protect from late frost using hot caps, floating row covers, or water-filled plastic cones.

Does tomato tolerate frost, heat, or drought?

Tomatoes are frost-sensitive at all growth stages; a hard freeze (below 28°F/–2°C for four consecutive hours) typically kills plants. They also struggle with temperature extremes: night temperatures below about 50–55°F prevent reliable fruit set, and high temperatures similarly cause poor pollination and flower drop. Spring and fall frosts limit the outdoor growing season across most of the continental United States.

Planting

How far apart should I space tomato plants?

Determinate varieties should be planted 2–2½ feet apart. Staked indeterminate varieties can be spaced 1½–2 feet apart within a row; caged indeterminate plants need 2½–3 feet; plants left to sprawl on the ground need 3–4 feet. Adequate spacing is critical for air circulation and disease prevention.

How far apart should the rows be?

Space rows 4 feet apart for most tomato types. Staked indeterminate plants need rows at least 3–4 feet apart; unsupported indeterminate plants spreading on the ground need rows at least 6 feet apart for walkable access at the end of the season.

Are there special planting techniques for tomato?

Black plastic landscape fabric laid over the bed before planting increases soil heat, controls weeds, and prevents the soil splash that spreads soilborne disease spores. Stripping lower leaves from transplants at planting removes the ‘ladder’ that soil-borne spores use to reach the plant.

What grows well next to tomato (companion plants)?

Basil repels aphids and hornworms; marigolds deter hornworms and aphids with their scent and color; alyssum attracts beneficial insects (hoverflies, ladybugs, lacewings) that control pests; chives repel aphids, nematodes, and spider mites; sunflowers attract native bees that improve pollination; asparagus keeps away nematodes in the soil; and onion, garlic, and other alliums mask tomato scent from pest insects.

What should I avoid planting near tomato?

Avoid planting near walnut trees, which release chemicals into the soil that stunt surrounding plants. Sweet corn attracts corn earworm, which also attacks tomatoes. Mature fennel and dill can stunt tomato growth. Do not replant tomatoes, potatoes, peppers, or eggplant in the same ground more than once in three years.

Watering

How much and how often should I water tomato?

Tomatoes need 1–2 inches of water per week with consistent deep irrigation, especially during fruiting. Container-grown tomatoes typically require watering once per day, sometimes twice on hot summer days; exact frequency varies with temperature, container size, and soil type. Consistent moisture—not flooding or drought—is the core goal.

What is the best way to water tomato?

Water at the base of the plants in the morning rather than in the evening, to keep foliage dry and minimize the time leaves stay wet, which reduces fungal disease risk. Spacing plants far enough apart helps foliage dry rapidly after rain or irrigation.

What are the signs of over- or under-watering tomato?

Lower leaves curling upward is a common sign of water stress (under-watering). Standing water deprives roots of oxygen and causes wilting. Inconsistent watering—alternating too much and too little—stresses plants and worsens physiological disorders such as blossom-end rot and fruit cracking.

Should I mulch tomato, and with what?

Yes. Mulch reduces soil splash that spreads soilborne disease spores, suppresses weeds, and conserves moisture. Grass clippings, shredded leaves, and straw all work well. Black plastic landscape fabric is particularly effective and has the added benefit of warming the soil.

Feeding & fertilizing

How should I fertilize tomato?

Feed with a balanced fertilizer—a 7-7-7 NPK ratio is one recommendation—to maximize yields. Water and fertilize to keep plants in vigorous condition, but avoid overfertilizing: overfed, fast-growing plants are more susceptible to disease and produce excessive foliage at the expense of fruit.

What fertilizer or nutrients does tomato need?

Tomatoes are heavy feeders requiring nitrogen, phosphorus, and potassium, plus calcium (calcium nitrate helps prevent blossom-end rot) and micronutrients including iron, magnesium, and manganese. Organic options include nettle liquid fertilizer, which supplies nitrogen, calcium, and magnesium.

When and how often should I feed tomato?

Liquid organic fertilizers such as nettle tea can be applied no more frequently than every three weeks, and typically every one to two months. Avoid excessive nitrogen feeding that drives rapid vegetative growth, as overfertilized plants are more prone to disease.

What are the signs of nutrient deficiency in tomato?

Interveinal yellowing (yellow tissue between green veins) indicates potassium, iron, magnesium, or manganese deficiency. Older leaves yellowing first points to nitrogen deficiency. Purple coloration on the undersides of leaves, primarily on transplants, indicates phosphorus deficiency.

Support, training & pruning

Does tomato need staking, caging, or a trellis?

All tomatoes benefit from some form of support. Staking with regular pruning to one or two main stems is the most space-efficient method and best for disease management because it maximizes air circulation. Indeterminate varieties especially require caging or staking; determinate varieties need less staking but still benefit from support.

How do I support tomato as it grows?

Stakes should be at least 1 inch thick and 6 feet high, inserted 1 foot into the ground; adding horizontal bamboo cross-pieces or twine between stakes improves stability. Wire cages are a lower-maintenance alternative. Train or tie stems to the support weekly as the plant grows.

Should I prune, train, or remove suckers from tomato?

Staked tomatoes must be kept to one or two main stems by removing all suckers—shoots that develop in the crotch between a leaf and the main stem. Pruning improves air circulation, reduces disease pressure, and promotes larger, faster-ripening fruit. At the first sign of early blight, remove all leaves within 12 inches of the ground.

Pollination & fruit set

Does tomato need pollinators, or is it self-pollinating?

Tomatoes are self-fertile—their flowers can pollinate themselves without a separate plant or variety. However, native bees attracted by companion plants such as sunflowers and chives help improve pollination rates and fruit set.

Why is my tomato flowering but not setting fruit?

Temperature extremes are the main cause: tomatoes fail to set fruit reliably when night temperatures drop below 50–55°F or when daytime heat is excessive. Excessive nitrogen (which promotes lush vegetative growth) and limited sunlight also prevent fruit set.

Why are the flowers dropping off my tomato?

Flower drop is most commonly caused by temperature stress. Night temperatures regularly dipping into the low 50s°F or below—common in coastal and high-altitude gardens—inhibit fruit set and cause flowers to abort. Excessive daytime heat has the same effect.

Pests

What pests commonly attack tomato?

Common pests include tomato hornworms, aphids, flea beetles, cutworms, spider mites, whiteflies, and stink bugs. Thrips are important because they transmit Tomato spotted wilt virus, particularly in greenhouses and high tunnels where tomatoes are grown alongside flower plugs.

How do I identify tomato pest damage?

Hornworms are large caterpillars with a red or black ‘horn’ that strip foliage from branches in mid-to-late summer. Flea beetles create tiny holes in a shothole pattern; the small, shiny, dark insects jump when disturbed. Aphids are small, soft pink or green insects found on young growth causing leaf curling. Spider mites cause tiny yellow stippling and a dirty appearance on leaf undersides.

How do I prevent tomato pests?

Companion plants help deter pests: basil repels aphids and hornworms, marigolds deter hornworms and aphids, and chives repel aphids and spider mites. Attracting beneficial insects through diverse plantings—including alyssum and sunflowers—reduces pest pressure. Regular monitoring allows early detection before infestations spread.

How do I control tomato pests organically and chemically?

Handpicking is the most effective method for tomato hornworms; hornworms bearing small white egg masses should be left alone, as those eggs belong to parasitic wasps that will further reduce the pest population. Companion plants such as basil and marigolds provide ongoing organic deterrence for aphids and hornworms.

Diseases

What diseases commonly affect tomato?

The most common diseases are early blight (Alternaria), Septoria leaf spot, late blight (Phytophthora infestans), bacterial spot, bacterial canker (Clavibacter michiganensis), and Fusarium and Verticillium wilts. In greenhouses and high tunnels, leaf mold, white mold, gray mold, and Tomato spotted wilt virus are also important. Bacterial wilt (Ralstonia solanacearum) is serious in warm, moist conditions.

How do I recognize tomato disease symptoms?

Early blight shows as small brown lesions with a concentric bull’s-eye ring pattern mostly on older lower leaves, with surrounding tissue turning yellow. Septoria leaf spot produces small round tan/gray spots with dark margins on lower leaves after fruit set begins. Bacterial wilt causes rapid plant collapse while leaves remain green; a cut stem shows brown discoloration with tiny drops of yellowish bacterial ooze. Fusarium and Verticillium wilts cause lower leaf yellowing with internal stem discoloration.

How do I prevent tomato diseases?

Use disease-resistant varieties; rotate tomatoes with non-solanaceous crops (especially corn) every 3–4 years; space plants adequately for airflow; water at the base in the morning; mulch to prevent soil splash; stake and prune for air circulation; eradicate weeds; plant only certified disease-free transplants; and remove and properly dispose of infected plant material—do not compost it.

How do I treat or manage tomato diseases?

For early blight, prune all leaves within 12 inches of the ground at first signs; disinfect clippers in a 1:9 bleach-to-water solution and do not remove more than 20% of total leaf mass at once. For bacterial wilt, remove and destroy all infected plant material—no chemical control is available. Fungicides can protect new tissue when used alongside cultural controls and should be used as a last resort, always following label directions.

Disorders & troubleshooting

What physiological disorders affect tomato (such as blossom-end rot, cracking, or sunscald)?

Common physiological disorders include blossom-end rot, sunscald, catfacing, and fruit cracking.

What causes these disorders and how do I prevent them?

Blossom-end rot results from impaired calcium uptake, triggered by cold soil (below 60°F) or inconsistent watering; applying calcium nitrate and maintaining even soil moisture helps prevent it. Fruit cracking occurs when a rapid influx of moisture after a dry period causes fruit to expand faster than the skin can stretch; consistent irrigation reduces cracking. Many physiological disorders are worsened by inconsistent watering.

Why are my tomato leaves yellowing, curling, or spotted?

Leaf yellowing can indicate nutrient deficiency (interveinal yellowing for potassium/iron/magnesium/manganese; older leaves first for nitrogen), Fusarium or Verticillium wilt (lower leaves with internal stem discoloration), or spider mite feeding (tiny yellow stippling, dirty undersides). Lower leaf curling upward typically signals water stress; leaf curling in hot weather may also be a varietal characteristic or heat stress. Mottled, deformed leaves indicate mosaic virus.

Why is my tomato not growing or producing well?

Poor growth or production most commonly results from insufficient sunlight, excessive nitrogen (which drives foliage over fruit), or temperature extremes—night temperatures below 50–55°F prevent fruit set. In cool or shaded gardens, selecting varieties with shorter days to maturity (55–75 days) and planting in the warmest available spot significantly improves output.

Harvest

How long does tomato take to mature?

Days to maturity (DTM) ranges from about 55 to 100 days from the date transplants are set in the garden. Cherry types average 55–65 days from transplant; standard slicers take 70–85 days. DTM is counted from outdoor transplanting, not from seed sowing, and plants in cool climates or at high altitude typically take longer than catalog listings suggest.

How do I know when tomato is ready to harvest?

Begin picking when tomatoes change color from green, first showing a yellow or blush hue at the blossom end (the side opposite the stem). Salad tomatoes are typically ready about 8 weeks after transplanting outside. Paste tomatoes should develop a rich, deep red color before harvest; wait until they are still slightly firm for easiest processing.

How do I harvest tomato correctly?

For paste tomatoes, wait for full deep-red color and harvest when still slightly firm for easier peeling and processing. For salad tomatoes prone to cracking, pick those beginning to show color before predicted rain and finish ripening on a countertop. Harvest all remaining fruit before the first frost to save the crop.

How often should I harvest tomato?

Harvest salad and cherry tomatoes approximately every three days to keep pests at bay and maintain healthy, productive plants that continue fruiting.

Can tomato ripen off the plant after picking?

Yes. Tomatoes picked at the breaker stage (first color change from green) will continue to ripen indoors on a countertop. This is a recommended strategy when frost threatens late-season fruit.

Storage, preservation & seed saving

How should I store fresh tomato, and how long does it keep?

Store fresh tomatoes at room temperature on a countertop to allow them to finish ripening and preserve flavor. Frost-damaged tomatoes—which turn mushy and develop brown spots—are not suitable for storage or further ripening.

How can I preserve tomato (canning, freezing, or drying)?

Freezing is the quickest method: chop tomatoes, cook them down in a stock pot for about two hours to reduce water content, then freeze in bags or wide-mouth glass jars. Traditional water-bath canning is also standard but more labor-intensive. Tomato paste is made by cooking tomatoes for several hours, straining out seeds and skins, then reducing further to a thick concentrate.

Uses & nutrition

What is tomato commonly used for in cooking?

Tomatoes are used fresh for salads, sandwiches, and burgers (beefsteak and slicers), for snacking (cherry types), and in sauces, salsa, soups, baking, and canning (paste/Roma types). Tomato paste—made from cooked, concentrated tomatoes with seeds and skins removed—adds intense umami flavor to pasta sauces, soups, and braised meats and is used worldwide.

What are the nutritional benefits of tomato?

Tomatoes rank number one in contribution of nutrients to the American diet, primarily because of the large quantities consumed—four out of five Americans prefer tomatoes to any other homegrown food.

Season extension & regional growing

How can I extend the tomato growing season?

In spring, start seeds indoors 6–8 weeks early, warm soil with black plastic, use raised beds (which warm faster), and protect transplants with row covers or Wall O’ Water cloches. In fall, top indeterminate plants in late summer, remove flowers and tiny late-season fruit that will not ripen, and harvest at the breaker stage to ripen indoors before frost. Late plantings made in early July can also yield a fall harvest.

Can I grow a fall or second crop of tomato?

Yes. Late plantings made in early July can produce a fall harvest and storage crop. Plants started later have the advantage of increased vigor and freedom from some early-season diseases.

How do I grow tomato in a particularly hot or cold region?

In cool or foggy climates, choose varieties with 55–75 days to maturity, plant in the warmest microclimate, and use season-extension tools such as row covers, Wall O’ Water, and raised beds. In Zone 3 (a ~90-day frost-free season), use 52–65 day varieties such as Stupice, Sub-Arctic Plenty, Early Girl, or Siletz; start seeds indoors around April 13; transplant after June 1 when soil reaches 60°F. In coastal climates, stack multiple techniques—soil warming, microclimate selection, consistent irrigation, and proactive disease management—to expand the short effective season.