How to Grow Tomatoes
Grow tomatoes in a pot or a garden bed, from choosing a variety that fits your space to planting deep, staking at planting time, watering evenly, and picking the fruit ripe.
You will end up with a tomato plant in the sunniest spot you have, planted deep, supported from the day it goes in, and picked when the fruit is ripe. Two things need the most care. The plant needs at least 6 hours of full sun, which Clemson Extension gives as the minimum, and soil kept evenly moist, because swings in moisture bring on blossom end rot (step 5).
An indeterminate (vining) plant keeps flowering and ripening fruit until the weather turns too cold, as Minnesota Extension puts it, so one healthy plant gives you tomatoes for months rather than weeks.
You do not need a big yard. A compact variety grows in a pot on a sunny balcony, and FAQ 1 below gives the pot size.
Tomato seedlings from a garden center (to start from seed instead, Clemson Extension sows indoors 6 to 8 weeks before the last frost date). A pot 14 to 20 inches across for a compact variety, or a 5-gallon bucket with drainage holes drilled in the bottom, or a garden bed with at least 6 hours of direct sun. Potting mix or garden soil amended with compost. A tomato cage, stake, or trellis for support. A watering can or hose. Optional but helpful: slow-release fertilizer or liquid tomato feed.
Choose the right variety for your setup
Tomato varieties fall into two growth habits, determinate and indeterminate. Determinate varieties grow to a fixed height, produce all their fruit in a short window, and then stop, which suits a container better than a plant that keeps climbing. Roma is the familiar example. Not every determinate plant is compact, though, so the height on the label is the thing to check. Indeterminate varieties keep growing and producing until frost kills them, so they need more room and taller support, and they give you tomatoes for months instead of weeks. Clemson's extension service lists Better Boy, Early Girl, Rutgers, Brandywine, and Cherokee Purple as indeterminate cultivars, which is exactly what makes them awkward in a pot. Cherry describes the size of the fruit rather than the habit of the plant, so cherry tomatoes turn up in both camps. Clemson names compact ones worth knowing about, including Patio Choice Yellow Hybrid, which tops out around 18 inches, and Tumbler Hybrid, whose mounded habit suits a hanging basket. For a first season, a compact cherry variety is a forgiving start. Read the tag for the habit and match the support to it rather than assuming cherry means small.
Good to know: Check the tag on the seedling for the number of days to harvest. Clemson's tomato factsheet puts the first harvest at 52 to 90 days, depending on the cultivar. If your growing season is short (northern climates), choose varieties with fewer days to maturity.
Pick a spot with maximum sun
Tomatoes need at least 6 hours of full sun a day, the minimum Clemson Extension gives. South-facing spots get the most sun in the Northern Hemisphere. Watch your potential spot throughout the day to make sure buildings, fences, or trees do not shade it during key hours. If you are growing in pots on a balcony, choose the sunniest side. Avoid spots that stay wet or have poor air circulation, because Clemson Extension notes that early blight starts on leaves where air movement is poor and humidity is high.
Plant deep for a strong root system
Remove the lower leaves, then dig a hole deep enough that only the top two or three sets of leaves stay above the soil, which is how deep Clemson Extension sets its transplants. Tomatoes grow roots along the buried stem, and those roots anchor the plant. If planting in a container, fill the pot with potting mix, make a deep hole, and bury the seedling the same way. Water the hole before placing the plant, set the seedling in, fill around it with soil, and water again thoroughly. Space plants 24 inches apart, in rows 3 feet apart, as Clemson Extension does.
Set up support right away
Install a tomato cage, stake, or trellis at planting time, as Minnesota Extension advises. Waiting until the plant is large risks damaging the roots when you push supports into the soil. Clemson Extension puts a cage or other support in at planting for any variety that grows taller than 2 feet. Tomato cages (the cone-shaped wire structures) suit compact and determinate plants, and Clemson says the wires should be at least 6 inches apart so you can reach in to harvest. For a tall indeterminate plant, use a wooden stake 6 feet tall, driven 1 foot into the soil about 4 to 6 inches from the stem, which is Clemson's method. As the plant grows, tie the main stem loosely to the support about every 10 inches with soft ties or strips of old T-shirt. Never use wire or thin string that can cut into the stem.
Water consistently and deeply
University of Minnesota Extension puts the ideal at about 1 inch of water a week, rain included. Water at the base of the plant, not overhead. Wet leaves promote fungal diseases like blight. Water deeply and less frequently rather than a little bit every day. Deep watering encourages roots to grow down, which makes the plant more drought-resistant and stable. In containers, water daily in the height of summer, as Clemson Extension advises, because pots dry out faster than garden beds. Stick your finger 1 inch into the soil. If it is dry, water. If it is still moist, wait.
Heads up: Blossom end rot is the dark, leathery spot on the bottom of the tomato. Clemson Extension calls it a physiological disorder, caused by a shortage of calcium in the developing fruit, and names extreme swings in soil moisture (dry then soaked, dry then soaked) among the things that bring it on. Keep the soil evenly moist, and spread mulch around the plant to help hold the moisture in.
Feed and maintain throughout the season
In the ground, feed once, when the first fruits start to enlarge, and skip even that if you worked plenty of compost into the bed, because Minnesota Extension warns that too much nitrogen gives you a bushy, leafy plant that is slow to fruit. In a container, use a timed-release fertilizer at planting or a water-soluble fertilizer once a week, as Clemson advises for potted tomatoes. Pruning depends on the habit. Minnesota Extension says bush (determinate) types need no pruning. For an indeterminate plant on a stake, Clemson Extension keeps one or two main stems and removes all the other shoots, called suckers (the small shoots that grow in the V between the main stem and a branch), once a week. A plant in a cage needs pruning once at most, and Clemson notes that the heavier leaf cover left on it shades the fruit from sunscald. Remove any yellowing lower leaves as the season progresses.
Harvest at the right time
Pick tomatoes when they are fully colored but still firm, which Clemson Extension says is when the flavor is best. Twist them off gently instead of pulling, so the stem does not break. If a frost is coming, pick the green fruit that has reached full size, especially any that is starting to turn white or pink, which Minnesota Extension says ripens well. Ohio State Extension calls a tomato that has reached full size mature green, and says fruit at that stage can be picked and ripened indoors. Ripen the picked tomatoes indoors at room temperature, one layer deep and not touching. They do not need light, and Clemson says not to refrigerate green fruit, because cold stops it ripening. Store ripe tomatoes at room temperature too. Clemson's factsheet warns that refrigeration can reduce the flavor and turn the texture mealy, which is a waste of a tomato you grew yourself.
If the plant grows big and leafy but is slow to set fruit, stop feeding it, because Minnesota Extension says too much nitrogen gives exactly that result. If only the lower leaves are yellowing, remove them and compare any spots with the early blight description in FAQ 2 below. If the fruit gets dark, leathery bottoms, even out your watering and add mulch (step 5). Start with one or two plants your first season, note how many hours of sun the spot really gets and how fast the soil dries out, and adjust the next year. Our guide on how to start a garden covers the soil, containers, and easy crops to grow alongside your tomatoes.
Questions we get asked about this
Answers from experience, not a textbook.
Yes. Clemson considers a 14- to 20-inch container suitable for most compact cultivars, and says a 5-gallon bucket with holes drilled in the bottom also works. What matters more is that whatever you use has real drainage. Use good-quality potting mix (not garden soil, which compacts in containers). Choose by plant size rather than fruit size. Clemson suggests looking for words like patio, balcony, or bush in the name and checking the mature height on the label. You will need to water more frequently than garden-planted tomatoes because containers dry out faster. A sunny balcony that gets 6 or more hours of direct sun is all you need.
A few yellow leaves at the bottom of an older plant, with no spots on them, are not a problem. Remove them to improve air circulation. Yellow leaves throughout the plant can indicate overwatering, nitrogen deficiency, or disease. Check your watering schedule first. If the soil is consistently soggy, cut back. If watering is fine, give it a dose of balanced fertilizer. Small brown spots with dark rings in a bull's-eye pattern, starting on the older leaves near the soil and ringed with yellow, are how Clemson Extension describes early blight, a fungal disease. Remove the affected leaves, mulch the soil, and water at the base instead of overhead.
Clemson's tomato factsheet gives 52 to 90 days to the first harvest, depending on the cultivar. Its own table shows how much that varies within a type. The cherry and grape tomatoes it lists run from 57 days (Sun Gold) to 70 (Super Sweet 100), and the larger slicers from 60 (Early Girl) to 82 (Rutgers). The number on the plant tag is the one to plan around. Once the plant starts producing, a determinate variety ripens its fruit within a 4- to 6-week window, according to Minnesota Extension, while an indeterminate one keeps ripening fruit until the weather turns too cold.
Check for hornworms (large green caterpillars that are hard to spot), squirrels, and birds. Hornworms leave dark green or black droppings and stripped stems, and Minnesota Extension says picking them off by hand is the most effective way to manage them. Squirrels and birds take bites out of ripening fruit. Cover the plant with bird netting, or pick the tomatoes once they start to turn pink and let them finish ripening inside (step 7). Slugs eat low-hanging fruit. Raise the lowest branches off the ground and remove any fallen fruit.
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