Vegetable · Solanaceae
Tomato
Solanum lycopersicum
Offer it full sun, steady water, and good airflow, and your tomato will keep giving back all summer long.
Full sun
Every 3–7 days
70–84°F · 21–29°C
50–90 days
Overview
Hardly anything feels more like summer than a ripe tomato you grew yourself. It's a member of the nightshade family with roots in the Andes, where it was tended long before it traveled out to the rest of the world. These days it settles in almost anywhere as a warm season annual, just as content in a garden bed as in a pot on a sunny balcony, so you have room to start small.
You'll find there's plenty of choice. Some plants keep low and bushy and bring their whole crop in over a week or two. Others stretch, ramble, and keep setting fruit all the way to frost. The low ones are called determinate and the tall ones indeterminate, and once you know which you've got, pruning and staking suddenly make sense.
Here's the reassuring part: tomatoes are kind to a beginner, and a little care goes a long way. Give them steady water, good sun, and breathing room, and the fruit comes in heavy and sweet. Skimp on those, and you'll mostly just see split skins and bare stems, which are easy to put right next time.
Care
The short version: give them full sun, with a bit of afternoon shade if your summers really sizzle. Keep the soil evenly moist with about an inch of water a week, set them in rich, fertile ground, and leave each plant a little elbow room to breathe.
Light
Give your tomatoes 8 or more hours of direct sun each day and they'll thank you. A little afternoon shade is welcome where summers get fierce, but real shade leaves you with tall, leggy plants and very little to pick.
Water
Try for steady, even moisture rather than a flood followed by a dry spell, and your plants will feel looked after. In practice that's about an inch of water a week, with extra during a hot stretch or in a pot. This gentle, even watering is exactly what keeps the skins from splitting.
Soil
Settle them into rich, well drained ground with a good helping of compost worked in. A pH of 6.0 to 6.8, leaning just a little acidic, is right where they're happiest, and loose, crumbly soil lets those deep roots stretch out.
Temperature
Your plants feel their best between 70°F and 84°F (21°C to 29°C). Fruit set takes a pause once nights stay warm or days run hot, and even a light frost will end the plant, so a little weather-watching pays off.
Humidity
Everyday outdoor humidity suits them just fine, so there's no figure to fuss over here. What really counts is good airflow, since crowded, damp leaves are how most tomato troubles get their start.
Feeding
Offer a balanced feed at planting time, then feed again once that first fruit has set. Go easy on the nitrogen, or you'll end up with a big leafy plant and not much to gather.
Pruning
On the tall indeterminate types, gently pinch out the side shoots so one or two main stems carry the plant. Leave the bushy determinate types as they are, since trimming them only costs you fruit.
Repotting
Shift seedlings into roomier pots before they head outdoors so their roots never start to circle. Once a plant is in its final bed or big container, it can happily stay put for the rest of the season.
Overwintering
Treat your tomato as an annual and you'll keep things simple. It's really a tender perennial at heart, but the first frost finishes it, so most gardeners just replant come spring with no worry.
Size & spacing
Depending on the type, plants reach anywhere from 2 to 10 feet (60 cm to 3 m) tall. Give each one 1.5 to 3 feet (45 to 90 cm) of space so air can drift through and disease has a harder time settling in.
When to plant
Tomatoes are warmth-lovers through and through, and frost is the one thing they truly can't take, so timing is your friend here. Get the seeds going indoors in late winter, ease the plants outside once the cold has lifted, and you'll be picking fruit from midsummer right up until that first frost calls it a season.
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
Most tomato troubles tip their hand early, usually on the fruit or the lowest leaves, and that's good news for you. Once you learn to spot those first little signs, you can step in calmly while it still makes a difference. Find what matches yours below, then go gently put it right.
Oily gray patches followed by a sudden collapse
Late blight is the one to act on without waiting, since it races through cool, damp weather and can flatten a plant in just a few days. Lift the whole plant out, seal it in a bag, and send it to the trash. Please don't add it to the compost, because that would carry the disease right into next year's garden.
Fix:
- Pull and bag plants immediately
- Do not compost
- Preventive fungicide on neighbors
Bottom leaves yellowing and drooping as the whole plant weakens
When a soil fungus like fusarium or verticillium wilt plugs up the stem from within, there's sadly no way to nurse the plant back, but this is not your fault and it's an easy thing to dodge next time. Lift the plant out, and come spring start over in a pot of clean mix or reach for varieties bred to brush this off.
Fix:
- No cure; remove plant
- Grow in containers with fresh mix
A dark, leathery spot forming under the fruit
Take heart, because blossom end rot is a watering hiccup and not a sign your soil has failed you. A plant that goes thirsty and then gets flooded can't carry calcium up to the fruit, so the base caves in. Settle into a regular watering rhythm, tuck mulch around the base to hold moisture, and gently pick off any fruit that already shows the mark.
Fix:
- Maintain even soil moisture
- Mulch root zone
- Remove affected fruit
Target-shaped brown spots creeping up from the bottom leaves
Those target-shaped marks are early blight, a fungus that wakes up in warm, soggy weather and creeps in from the bottom of the plant. You can stay ahead of it: clip away the spotted leaves, give the plant a little room so air can flow through, and try to keep the leaves dry when you water.
Fix:
- Remove infected lower leaves
- Improve airflow
- Apply fungicide if severe
Many tiny gray dots ringed in darker brown
When wet weather settles in, septoria leaf spot can freckle the lower leaves, and it looks worse than it is. As soon as you notice the marks, pinch off those leaves, lay down mulch so rain can't bounce spores back up, and pour your water at the soil line rather than over the top.
Fix:
- Remove infected leaves
- Improve air circulation
- Fungicide if severe
Whole branches bare by morning with dark pellets underneath
Don't be alarmed if a branch turns up bare with dark crumbs underneath, because a single tomato hornworm can do that in one night. The good news is they're easy to deal with: go out at dusk and pluck the plump green caterpillars off with your fingers. If one wears tiny white cocoons, let it stay, since helpful wasps are already handling it for you.
Fix:
- Hand-pick caterpillars
- Leave any with white wasp cocoons
- Spray Bt if heavy
Blossoms turning yellow and falling before any fruit forms
If the blossoms keep falling off, the heat is usually the culprit, not anything you did wrong. Once nights linger above 70°F (21°C) or days push past 85°F (29°C), the plant simply pauses on fruit. Keep it watered and be patient, because it picks right back up once the weather eases.
Fix:
- Keep plants irrigated
- Wait for favorable temperatures
Split skins circling or fanning out over the fruit
A split skin just means the fruit took a big drink after a dry stretch and grew faster than its skin could keep up. There's nothing to worry about here, and the fix is gentle: water on an even rhythm and lay down some mulch to smooth out the swings. If a downpour is coming, you can simply pick the fruit a touch early.
Fix:
- Pick fruit before fully ripe
- Keep watering even
Fruit that looks pinched and scarred on its underside
This lumpy, scarred look has a friendly name, catfacing, and it goes back to a chilly spell while the flowers were forming. Rest easy, because the fruit tastes just fine and is perfectly good to eat. Next year, wait for the soil to warm and the last cold nights to pass before you set your transplants out.
Fix:
- No cure for set fruit; remove affected
Yellowing showing up on the very lowest, oldest leaves
A handful of yellow leaves right down at the bottom is usually nothing to fret over, just the plant letting old growth go while it pours itself into the fruit. Keep an eye out, though: if the yellow starts climbing higher or the whole plant looks washed out, offer it a balanced feed and have a quick look for spots or wilting.
Fix:
- Apply balanced fertilizer if deficient
- Remove diseased tissue
Toxicity
The ripe fruit is wonderful to eat, but the rest of the plant is best left alone. Leaves, stems, and unripe green tomatoes carry a natural compound called solanine that can upset the stomach. To keep everyone comfortable, simply keep the green parts out of reach of pets, livestock, and curious little ones.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People — the ripe fruit
Cats Moderate
A nibbling cat may drool, feel queasy, and turn sluggish. If it eats a good deal, you might also see the pupils go wide and the heartbeat slow down.
Dogs Moderate
Once a dog has chewed the leaves or stems, watch for drooling, a turned-off appetite, a queasy belly, and a bit of weakness.
Horses Moderate
Eating the green parts tends to leave a horse with a sour stomach, a flat mood, and some weakness.
Rabbits Toxic
Solanine sits in the leaves and stems, so those parts simply aren't safe for a rabbit. A few bites of ripe fruit make a fine treat now and again.
Livestock Moderate
Cattle, goats, and sheep that browse the foliage can run into stomach upset and nervous system trouble from the solanine it holds.
Birds Caution
Since the green parts carry the toxin, stick to ripe fruit and only as an occasional bite. A backyard hen can safely peck at a ripe tomato.
People Ripe fruit safe
Ripe tomatoes are a much-loved kitchen favorite and perfectly safe on your plate. Just steer children clear of the leaves and any 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
There are thousands of tomatoes out there, but only a handful show up in most gardens. These are the friendly few worth knowing by name.
Early Girl
A speedy climber that rewards you with ripe slicers in roughly 60 days, well before most others get going.
San Marzano
The much-loved paste tomato, whose long, low-seed fruit simmers down into a deep and full-bodied sauce.
Roma
A tidy bush type favored for canning and sauce, ripening nearly all its fruit together in one short stretch.
Celebrity
A trusty, easygoing pick that brushes off most of the diseases that bother other tomatoes.
Beefsteak types
Tall climbers carrying the biggest, richest-tasting slices, though their hefty fruit is more prone to splitting.
Cherry types
Bite-size sweet fruit strung along long trusses that just keep coming all season, with friendly names 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 are one of the easiest plants to make more of, so don't be shy about trying, whether you open a fresh seed packet or take free copies off a plant you already love.
SeedEasy
Indoors 5-8 weeks before last frost · Germinates 5-10 days at 75-85°F (24-29°C)
Starting from seed is the path most gardeners take, and it's a lovely one to learn on. Sow indoors 5 to 8 weeks before your last frost, keep the tray cozy at around 75°F to 85°F (24°C to 29°C), and you'll spot little sprouts pushing up in 5 to 10 days. When moving day comes, set them in deep and bury part of the stem, because each buried inch sends out brand new roots for you.
Stem cuttingsEasy
During active growth · Roots in 1-2 weeks in water or moist soil
Here's a delightfully forgiving trick: tomatoes copy themselves with hardly any effort on your part. Break off a healthy sucker from a growing plant, pop it in a glass of water or a pot of damp soil, and within a week or two it roots into a whole new plant that's the spitting image of its parent.
Myths
Sprinkling eggshells or extra calcium into the soil will heal blossom end rot.
It helps to know the issue is how the plant carries calcium, not whether enough sits in the ground. Eggshells are far too slow to break down to make any difference, and a spray on the leaves never reaches where the fruit needs it. Watering on a calm, even schedule is what truly turns it around.
A little Epsom salt in the planting hole brings bigger plants and a heavier harvest.
Unless your soil happens to be low on magnesium, which seldom happens, it simply won't do a thing. Piling it on can actually push blossom end rot along by elbowing aside the calcium the fruit is counting on.
Watering while the sun is out scorches the foliage, since each droplet acts like a tiny lens.
You can water without worry, since the beads dry away well before they could ever scorch a leaf. Scorched or spotted leaves come from disease, pests, or weather, and never from sunlight passing through a drop of water.
Marigolds keep every garden pest away.
Their helpfulness is real but narrow. French marigolds do hold back whiteflies and may take a little pressure off thrips, yet they won't sweep away pests across the board, and a lot of companion advice leans on old garden lore more than careful trials.
Removing every last sucker guarantees a bigger tomato harvest.
With the tall climbing types, trimming does bring earlier, larger fruit, but it can also leave you a smaller harvest overall plus a touch more sunscald. With the squat bushy types, the kindest thing is to let the suckers stay.
Extra nitrogen feeding translates into extra fruit.
Pile on the nitrogen and you'll raise a big, leafy plant that barely fruits, and what fruit it does give is quicker to crack. A gentle, balanced feed will serve you so much 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