Vegetable · Solanaceae
Tomato
Solanum lycopersicum
Hand it full sun, steady water, and good airflow, and the tomato keeps the harvest coming all summer.
Full sun
Every 3–7 days
70–84°F · 21–29°C
50–90 days
Overview
Nothing tastes more like high summer than a sun-warmed tomato, its skin taut and glossy red. The plant sits in the nightshade clan and descends from the high Andes, where it was cultivated long before reaching the wider world. Now it thrives nearly everywhere as a warm season annual, content in a sprawling garden row or rising from a pot on a sun-struck balcony.
The range of forms is broad. Some plants hold low and dense, packing fruit onto a stout frame that ripens within a week or two. Others scramble skyward, throwing out leggy stems and setting fruit until frost cuts them down. The squat sort goes by determinate and the climbing sort by indeterminate, and which you grow decides how you pinch and stake it.
A tomato pardons the beginner yet repays a careful hand. Hand it steady water, full sun, and open air around the leaves, and the fruit swells heavy and sweet on the vine. Skimp on those and you swap that flavor for split skins and bare stems.
Care
The short version: full sun, with a little afternoon shade where the heat bears down hard. Hold the soil evenly damp at roughly an inch of water a week, set the roots in rich, fertile earth, and give every plant elbow room for the air to slip through.
Light
A tomato hungers for 8 or more hours of direct sun each day, its leaves drinking in the light. A patch of afternoon shade earns its keep where summers scorch, but deep shade leaves you with lanky, sprawling plants and a thin harvest.
Water
Reach for steady, even moisture rather than a drowning followed by a drought. In practice that lands near an inch of water a week, climbing higher through a heat wave or in a pot. That level rhythm is what keeps the taut skins from bursting.
Soil
Settle the roots into rich, well drained ground loaded with compost worked deep. A pH of 6.0 to 6.8, just shy of neutral on the sour side, suits a tomato, and crumbly, loose earth lets its long roots dive.
Temperature
Growth peaks between 70°F and 84°F (21°C to 29°C). Fruit set stalls when nights stay sultry or days bake hot, and the faintest frost lays the whole plant down.
Humidity
Plain outdoor air carries enough moisture, so chase no figure here. Good airflow matters far more, since leaves left crowded and damp are the doorway through which most tomato diseases walk in.
Feeding
Work in a balanced feed as you plant, then feed once more after the first fruit holds. Keep a light hand on the nitrogen, or you'll raise a towering leafy plant with barely a tomato to show.
Pruning
On the tall indeterminate climbers, pinch the side shoots back to one or two leading stems. Let the squat determinate bushes grow untouched, since cutting them only robs you of fruit.
Repotting
Shift seedlings into wider pots before they go outdoors so the roots never wind into a knot. Once a plant lands in its final bed or big container, it stays put for the rest of the season.
Overwintering
Treat the tomato as an annual. It's a tender perennial deep down, but that first frost finishes it, so most gardeners simply sow fresh each spring.
Size & spacing
Depending on the type, plants stretch from 2 to 10 feet (60 cm to 3 m) tall. Leave each one 1.5 to 3 feet (45 to 90 cm) of breathing room so air flows and disease keeps its distance.
When to plant
A tomato craves heat and will not stand a breath of frost. Sow the seed indoors while winter still lingers, carry the plants outside once the cold has loosened its grip, and gather fruit from high summer until that first frost shuts the season down.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 5–8 weeks before last frost (start seeds indoors before last frost)
- Plant: at last frost to 2 weeks after (after frost, soil ~60°F (16°C))
- Harvest: July–October (midsummer to first frost)January–April (midsummer to first frost)
Hardiness
USDA hardiness zones: 10–11
Temperature: down to -1°C
Troubleshooting
Trouble in a tomato patch tends to surface first on the fruit itself or down among the lowest leaves. Train your eye on those early clues and you can move in before a small fault runs wild. Find the match below, then act while there's still ground to gain.
Slick gray-brown smears spreading as the plant caves in
Slick gray-brown smears spreading overnight signal late blight, which races through chilly, sodden air and flattens a healthy plant within days. Yank the whole thing, seal it in a bag, and throw it out. Compost it and you gift the rot to your soil for next year.
Fix:
- Pull and bag plants immediately
- Do not compost
- Preventive fungicide on neighbors
Bottom leaves gilding yellow and slumping as the plant fades
When the bottom leaves gild yellow and droop as the plant slowly fades, suspect fusarium or verticillium wilt, a soil fungus that plugs the stem from within with no remedy once rooted. Tear the plant out and begin again next year in a tub of clean mix, or pick cultivars bred to shrug it off.
Fix:
- No cure; remove plant
- Grow in containers with fresh mix
A dark, leathery crater pressed into the fruit's base
That brown, leathery dent at the base of each tomato is blossom end rot, born from a swing between bone-dry roots and a sudden flood rather than thin soil. Calcium can't travel into the fruit when moisture lurches that way. Hold a level watering rhythm, lay down mulch to bank the wet, and twist off any fruit already scarred.
Fix:
- Maintain even soil moisture
- Mulch root zone
- Remove affected fruit
Concentric brown targets stamped across the lower leaves
Concentric brown targets riding the bottom foliage point to early blight, a fungus that wakes up in muggy heat and creeps upward from the ground. Clip away the ringed leaves, thin the canopy so breezes pass through, and aim the hose at the roots so the foliage stays dry.
Fix:
- Remove infected lower leaves
- Improve airflow
- Apply fungicide if severe
A stipple of tiny gray specks inked with dark rims
A scatter of tiny gray flecks rimmed in dark ink across the lower foliage is septoria leaf spot, which settles in once the air turns soggy. Strip the freckled leaves the moment they show, mulch the ground so rain can't bounce spores upward, and pour water low at the stem.
Fix:
- Remove infected leaves
- Improve air circulation
- Fungicide if severe
Stems gnawed bare by dawn over a litter of dark pellets
Bare stems and a litter of dark pellets beneath them mean a tomato hornworm is at work, a plump green caterpillar that can gut a branch between dusk and dawn. Hunt the fat green bodies by hand in the evening light and lift them off. Spare any studded with little white cocoons, since braconid wasps have already claimed that one.
Fix:
- Hand-pick caterpillars
- Leave any with white wasp cocoons
- Spray Bt if heavy
Yellowed blossoms shriveling and dropping before any fruit forms
Blossoms that pale, shrivel, and fall without forming a single fruit are reacting to heat: nights that stay above 70°F (21°C) or days that crest past 85°F (29°C). Keep the roots watered and let the weather turn. The flowers begin holding fruit again on their own once the air cools off.
Fix:
- Keep plants irrigated
- Wait for favorable temperatures
Splits ringing the shoulder or fanning over the fruit's skin
Taut skin splits when a parched stretch gives way to a deep drink and the flesh balloons faster than the rind can stretch around it. A steady drip and a blanket of mulch smooth out those surges. Harvest a touch green when a downpour is forecast.
Fix:
- Pick fruit before fully ripe
- Keep watering even
Ridged, deeply scarred fruit pitting the underside
Lumpy, ridged tomatoes pitted with deep scars on their underside show catfacing, the lasting fingerprint of a cold snap that struck while the blooms were taking shape. The flesh tastes fine all the same. Wait to set transplants out until the ground has warmed and the last hard chill is behind you.
Fix:
- No cure for set fruit; remove affected
A yellow tide washing over the oldest leaves at the base
A handful of yellowing leaves down at the ankles of the plant usually just marks old age, as it funnels its strength up into ripening fruit. Should that yellow tide climb higher or the whole canopy turn sallow, offer a balanced feed and scan the foliage for spots or wilt.
Fix:
- Apply balanced fertilizer if deficient
- Remove diseased tissue
Toxicity
The ripe red fruit is a delight to eat, yet the rest of the plant is off limits. Leaves, stems, and hard green tomatoes carry a natural compound named solanine that turns the stomach. Hold the green growth out of reach of pets, livestock, and inquisitive children.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People — the ripe fruit
Cats Moderate
Watch for a drooly mouth, a queasy gut, and a sluggish cat. A bigger nibble can blow the pupils wide and drag the heartbeat slow.
Dogs Moderate
A dog that has gnawed the stems or foliage may turn drooly, go off its food, churn at the stomach, and grow weak in the legs.
Horses Moderate
Munching the green growth can leave a horse queasy, dull-eyed, and weak.
Rabbits Toxic
Stems and foliage carry solanine and stay off the menu. Hand over only tiny morsels of ripe fruit now and then.
Livestock Moderate
Cattle, goats, and sheep that graze the solanine-laced leaves can suffer gut churn and jittery nerves.
Birds Caution
Green growth is poison, so pass along ripe fruit alone and only on occasion. A backyard hen can peck a red tomato without harm.
People Ripe fruit safe
A ripe red tomato is a kitchen mainstay and perfectly safe on the plate. Steer children clear of the leaves and the green fruit.
Ripe fruit is non-toxic; keep pets away from leaves, stems, and green fruit
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Tomato varieties number in the thousands, though only a few show up in garden after garden. These are the names worth carrying in your head.
Early Girl
A quick vining variety that drops ripe slicers into your hand in roughly 60 days, well before the rest of the patch.
San Marzano
The legendary sauce tomato, its long, thin-seeded fruit melting down into a dark, full-bodied sauce.
Roma
A squat bush type prized for the jar and the saucepan, dropping its whole crop in one short burst.
Celebrity
A trusty middle-of-the-road grower that brushes off most of the diseases plaguing its neighbors.
Beefsteak types
Hefty vining slicers carrying the deepest flavor, though their weighty fruit cracks open more readily.
Cherry types
Tiny sweet globes strung along long trusses that keep producing right through the season, like Sungold and Sweet 100.
Companions
Tomatoes grow best beside herbs and flowers that pull pests away, and worst beside their nightshade cousins, which trade the same diseases back and forth.
Plant near
Basil: Studies show basil can reduce thrips on tomato and intercropping may promote tomato growth
French marigold: Slows glasshouse whitefly population through airborne limonene when planted early in season
Nasturtium: Non-host plant shown to reduce whitefly numbers on tomato
Keep apart
Corn: The corn earworm and tomato fruitworm are the same insect, so the pest builds up on both crops; both are heavy feeders competing for nutrients
Potato: Same Solanaceae family; shares early and late blight, so avoid planting together or in sequence
Pepper: Solanaceous relative sharing tomato diseases; avoid adjacent planting and rotation
Eggplant: Solanaceous relative sharing soilborne diseases and pests with tomato
Black walnut: Roots release juglone; tomatoes are highly sensitive, causing yellowing, wilting, and death near the dripline
How to propagate
Tomatoes rank among the simplest plants to multiply, whether you tear open a seed packet or take free copies off a plant already in your care.
SeedEasy
Indoors 5-8 weeks before last frost · Germinates 5-10 days at 75-85°F (24-29°C)
Seed is where most tomato growers begin. Tuck the seed into trays 5 to 8 weeks before your last frost, keep the soil cozy at 75°F to 85°F (24°C to 29°C), and tiny green shoots push up through the surface in 5 to 10 days. At transplant time, sink each seedling deep with part of its furry stem underground, since every buried inch sprouts new roots.
Stem cuttingsEasy
During active growth · Roots in 1-2 weeks in water or moist soil
Few plants copy themselves as readily as a tomato. Pinch a sturdy sucker from a thriving plant, drop it into a jar of water or press it into damp soil, and pale roots feather out within a week or two, giving you a fresh plant that mirrors the parent exactly.
Myths
Digging in calcium or crushed eggshells will heal blossom end rot.
The snag lies in how the plant ferries calcium around, not in the amount buried in the dirt. Crushed eggshells rot away far too slowly to matter, and a spray misted on the leaves never travels to the fruit. Steady, even watering is the real fix.
A pinch of Epsom salt swells the tomatoes and piles on the harvest.
It accomplishes nothing unless your ground happens to lack magnesium, and that shortfall is uncommon. Too much can even make blossom end rot worse by elbowing aside the calcium the fruit relies on.
Droplets clinging to sunlit leaves sear them like a magnifying glass held to paper.
Beads of water evaporate well ahead of any chance to sear. Spotted, scorched leaves trace back to disease, pests, or weather, and never to sunlight slipping through a droplet.
Marigolds keep every garden pest away.
The payoff is narrow. French marigolds do slow whiteflies and may nudge back a few thrips, yet they leave most pests untouched, and a great deal of companion advice leans on old garden lore over real trials.
Plucking away every sucker always swells the tomato count.
On lanky vining stock, snipping suckers yields larger, quicker fruit yet often a smaller total harvest along with more sunscald. On squat bush stock, let every sucker stay put.
Heaping on nitrogen fertilizer swells the tomato yield.
A heavy hand with nitrogen raises a lush, leafy plant with little fruit, and pushes the few tomatoes you harvest toward cracking. A balanced feed serves you far better.
Sources
- ASPCA Animal Poison Control
- University of Minnesota Extension
- University of Maryland Extension
- Clemson Cooperative Extension HGIC
- University of Maryland Extension
- Clemson Cooperative Extension HGIC
- Clemson Cooperative Extension HGIC
- University of Minnesota Extension
- Penn State Extension
- University of Minnesota Extension
- PLoS One (peer-reviewed)
- University of Wisconsin-Madison Extension (Wisconsin Horticulture)
- Penn State Extension
- University of Maryland Extension
- University of Illinois Extension
- Penn State Extension