How to Grow Tomatoes in Pots

An invaluable growing method for both apartment-dwellers and homeowners not blessed with fertile soil, container growing comes to the rescue even for larger annual edibles such as tomato plants (Solanum lycopersicum).

Planting pot (minimum 18 inches in diameter)

Potting mix 

Small pruners

Trowel

Watering can

Water-soluble tomato food 

How large a container you'll need for your tomato plant depends on what variety you're growing. Rather than considering the size of the tomatoes it will produce, check the seedling label to see whether the plant is indeterminate -- the big, sprawling, kind -- or the more compact determinate plant. The latter often works better for container gardening, but it is possible to "contain" larger tomato plants. In general, a pot that is 24 inches or more in diameter will hold an indeterminate tomato variety, and one that is 18 inches or larger will be big enough for determinate types.

Tomatoes that were bred specifically for container growing include 'Burpee's Pixie,' 'Small Fry,' 'Tiny Tim' or 'Tumbler' cherry tomatoes, and 'Patio Hybrid' for standard-size tomatoes. These cultivars are all small enough to fit in pots as small as 5 gallons.

If you will be needing to move your tomatoes to keep them in the sun, or to position them for watering, avoid whisky barrels, as well as other heavy materials such as ceramic and terra cotta. Instead, look for plastic and fiberglass pots, which are lightweight -- or consider re-purposing a 5-gallon bucket. Whatever you choose, make sure it either comes with drainage holes, or has a surface that can be punctured with a drill, or a hammer and nail, to create holes.

You may be able to find a pre-blended potting mix which is geared to growing tomatoes. Look for one that mentions tomatoes on its package, and which includes slow-release fertilizers and water-holding gels, as well as premium blend such as perlite, compost, peat moss, vermiculite and sand.

Alternatively, create your own mix by blending equal parts compost, potting soil, perlite and sphagnum peat moss. You might also choose to add about 1 cup dolomitic limestone for every 40 pounds of potting soil, along with 1/2 cup each of a prepared trace element mix, as well as powdered iron.

Make sure whatever blend you choose is thoroughly mixed before it goes in the container.

Strip your tomato seedling of its lower leaves by pinching them off near the stem. This is the best way to encourage a strong stem and root system as the plant grows.

Fill the pot about two-thirds full of your potting mix. If the drainage holes in your container are large ones, you can cut screening to size and place it at the bottom, before pouring in the soil. This will keep the soil from washing away after rainfall or watering.

Place your tomato plant in the center of the container, and bury the stem up to its upper leaves. The bushy nature of tomato plants often means that only one will fit per container. The exception to this rule comes when you have a whiskey barrel or other large pot, as well as a few "tumbler" or other small varieties. Two or three of these can go in at a spacing of about 24 inches apart, or as noted on the nursery tag.

Gently insert a tomato cage around the inside edges of the pot, or set a sturdy stake a few inches behind the plant. Setting up the support system at planting time means that you won't damage expanding roots later on.

Some gardeners prefer to only partially fill their container before planting the tomato seedling, and slowly add soil as the tomato grows. If you do this, make sure to pinch off the foliage on the section of stem you are about to bury.

Tomatoes are sun-lovers, so place your pots where they will receive at least six hours of sun. 

Container soil is notorious for drying out more quickly than that of traditional garden beds, especially when in clay pots. If the soil feels dry when you poke your finger into the first 1 or 2 inches, run a hose or watering can over the soil until water runs out the drainage holes. You may need to water daily during dry, hot weather.

About halfway through the growing season, begin supplementing the slow-release fertilizer in your potting mix with a water-soluble solution made for tomatoes. Typically, you'll mix about 1 ounce of the concentrate per 1 gallon of water, then water the tomato plant with it, leaves and all, but always check your tomato food's label. Nourish the tomato plant with this mix every two weeks, or as suggested on your fertilizer's package.