Tomatoes are warm-season, slow-growing vegetables that take as much as 150 days to mature from seed, so in all but the warmest climates, they are usually planted from well-developed nursery starts in the spring after the soil has fully warmed. If started from seed, they need to be sown indoors several weeks before the last frost of the spring.
Determinate vs. Indeterminate Tomatoes
Tomatoes are generally categorized as determinate types, which produce all their fruit in one confined period, or indeterminate types, which continue to produce fruit over the entire mature growing season. Determinate tomatoes tend to be more compact plants, and for that reason are sometimes known as bush tomatoes. Indeterminate types tend to be long, sprawling plants, and are sometimes known as vining tomatoes. When growing patio containers, indeterminate tomatoes will need supports or trellises to keep them supported. Determinate tomatoes often are available in nicely compact plants that work well in pots, though you won’t get as much fruit from them.
Heirloom vs. Hybrid Tomatoes
Traditionally, nearly all grocery store tomatoes and most garden-grown tomatoes are hybrids—carefully developed varieties that seek to maximize color and shelf-life, sometimes at the expense of unique taste and colors. Increasingly popular though, are so-called heirloom tomatoes, sometimes considered organic tomatoes. These are typically either original species or cultivars immediately descended from those species. They may have unusual shapes and colors, and often have a unique taste (many people say better) than store-bought tomatoes. The cost of growing these tomatoes is a plant that may be more susceptible to some common tomato pests and diseases. Heirloom tomatoes once were the territory of gardeners willing to grow tomatoes from seeds, but many garden centers now offer a variety of heirloom plants along with their hybrid tomatoes. Two other things to consider are mulching and support. Even compact tomato varieties benefit from some support. Tomato cages, stakes, or homemade cages made to fit the container are all good options. Mulching, while less important in a container than in a garden bed, is still a good idea — it keeps weeds from growing in the tomato pot and retains moisture so you won’t have to water quite as often. The best mulches are pebbles, bark mulch, and straw. If you prefer to use plastic, position it over the soil before you plant the tomato, cut a slit large enough to put the plant in, and secure the plastic with metal stakes.
Tomato Care
Light
Tomatoes require a full day of sun in order to produce adequately. Six hours of full sun is considered a minimum.
Soil
Any good quality organic potting soil works for tomatoes—don’t use soil dug directly from the garden. It is too heavy for container gardens, and it compacts more as the season goes on. Good peat or compost-based soil, whether purchased or mixed from your special recipe, is ideal.
Water
Tomatoes need moisture, so be sure to water regularly. The best way to tell when to water is to stick your finger into the soil; if the first two inches are dry, it’s time to water.
Temperature and Humidity
As natives of Central American and northern South America, tomatoes are hot-season vegetables that cannot receive too much heat—provided they receive plenty of moisture at the same time. Too much heat early in the growth can stunt the flowering, but mature plants thrive at temperatures from 80 degrees Fahrenheit to the 90s. If nighttime temperatures will fall below 55 degrees Fahrenheit, make sure to choose cold-tolerant varieties. Tomatoes generally like a moderately humid environment, though not tropical. There are varieties well-suited for dry climates.
Fertilizer
The trickiest thing about growing tomatoes in a pot is that they are heavy feeders, and every time you water, you wash nutrients out of the soil. To combat this, fertilize regularly, preferably with either fish emulsion or seaweed extract. Once a month is good, but every other week, applying the fertilizer at half-strength, is better. This provides a constant source of nutrients for the tomato plants.
Tomato Varieties for Containers
Indeterminate tomatoes are favorites for general gardening because they continue to produce fruit all season long, but most of these varieties are not great choices for containers because they tend to be sprawling, vining plants. Thus, compact bush types, with some exceptions, are often the best choice for growing in pots and other containers. There are exceptions, though, as there are some indeterminate types bred for container use.
‘Patio Princess’ reaches 2 feet tall with a continual stream of 2 1/2-inch tomatoes.‘Bushsteak’ produces large, juicy tomatoes on plants that are only 20 to 24 inches tall.‘Sweetheart of the Patio’ produces delicious 1-inch tomatoes, and plenty of them.‘Marglobe’ is a vining plant that requires a large container, but the profuse harvest makes it worthwhile. Fruit is ripe within 73 days.‘Baxter’s Bush Cherry’ produces a lot of fruit and is ideal for containers, as it won’t need staking or caging.‘Sweet Baby Girl’ is an indeterminate type, but it doesn’t get too tall, making it excellent for containers.‘Gardener’s Delight’ is a wonderful heirloom cherry tomato with a taste that is both rich and sweet.‘Balcony’ is a compact plant ideal for small containers. It produces a surprising number of 2- to 2 1/2-inch bright red tomatoes.‘Stupice’ is known for early tomatoes, 2- to 3-inches in diameter.‘Tumbling Tom Yellow’ bears lots of 1- to 2-inch yellow tomatoes. It works well in hanging baskets, railing boxes, and other containers.
How to Grow Tomatoes in Pots
After you find the perfect plant, it is time to plant it. In general, plastic or fiberglass pots are best for growing tomatoes for a few reasons. Plastic and fiberglass, unlike clay pots, don’t dry out quickly, and while tomatoes love heat, they don’t like being dry, and dry soil is a huge detriment to fruit production. Tomatoes need to grow in a reasonably large pot—at least 8 inches deep and preferably 12 to 16 inches. Plastic is inexpensive, even for huge pots, and it’s unlikely to break the way clay so often does. For a cheap option, you can plant tomatoes in a five-gallon bucket (readily available at home improvement stores). They are the perfect size, and the price can’t be beaten. After you have the perfect pot, make sure that it has adequate drainage; the tomato plant will rot if it is sitting in soggy soil all the time. Most purchased pots have drainage holes in the bottom already, but if you’re using a five-gallon bucket, drill several holes in the bottom. If the pot you are using has large drainage holes, use a piece of a broken pot, a piece of window screening, or a paper coffee filter to cover it. This way the water can drain out, but the soil won’t end up all over the patio.
Harvesting Tomatoes
Contrary to what some people believe, tomatoes do not need to be harvested early and then allowed to ripen on a shelf. They will be most edible when the color reaches a deep red (or yellow, for certain varieties). Unripe or early fruit will continue to ripen if you place them on a sunny shelf or in a paper bag with an apple. Indeterminate tomatoes will continue to produce new fruit as you continue to pick the fruit. For larger tomatoes, pinch back the growing tips of branches to remove flowers. This causes the plant to put its energy into the remaining flowers and fruit.
How to Grow Tomatoes From Seed
Because tomatoes are warm-season plants that take a long time to mature, they are often started from seeds indoors, at least six to eight weeks before the last spring frost. This can be the only way to grow certain organic heirloom varieties, where nursery plants are not available at all. In a cell tray filled with potting soil, sow the seeds 1/2 inch deep. Place the tray in a well-ventilated sunny area that’s at least 70 degrees. Experienced gardeners often use a heat mat and small fan to provide ideal conditions. Within five days or so, the seeds should sprout. Keep the seedlings warm and moist until they are 2 to 3 inches tall, at which time they can be transplanted into larger pots. Continue to grow in bright, sunny conditions until the weather warms and all danger of frost has passed. To aid the transition outdoors, “harden off” the young plants by giving them increasingly long visits to outdoor conditions over a period of seven to ten days, bringing them indoors at night. Tomatoes are very sensitive to cold, so they need to be slowly acclimated to outdoor conditions in order to avoid shock.
Common Pests/Diseases
Tomatoes grown in containers are usually less susceptible to problems than those grown in the ground, but they can still be prone to some common ailments.
Blossom end rot presents as ugly black patches on fruit that seem otherwise healthy. It is usually caused by a lack of calcium in the soil, exacerbated by uneven watering, which is often a problem in container culture. Some gardeners blend in eggshells or bone meal to potting soil to prevent this.If blossoms drop off your plants before fruit can form, it is usually caused by temperatures that fluctuate too much. There’s nothing you can do about blossom drop, but keeping the plant strong will minimize it.Cracking fruit occurs when tomatoes take up moisture too rapidly, as often happens during hot, wet weather. Don’t worry too much, as the tomatoes are still edible.Tomatoes are also prone to a variety of fungal leaf spots. Minimize these problems by keeping the foliage as dry as possible.Cutworms sometimes sever plants at ground level. Protecting the base of stems with collars of aluminum foil can prevent this.
