13 Tips For Growing Tomatoes in Pots or Containers
Growing tomatoes in pots or containers can be great for gardeners that lack the space of a full vegetable garden. Tomatoes can be picky plants to grow, so it's important to make sure meet all their needs. In this article, gardening expert Sarah Hyde provides her top tips for growing tomatoes in pots or containers this season.
Do you love the taste of home grown tomatoes but don’t have a garden space of your own? With just a small area and a bit of planning, you can enjoy eating your own container-grown tomatoes!
Tomatoes are one of the easier veggies to grow in your garden, which makes them a favorite amongst vegetable gardeners both new, and seasoned. As long as you can manage their pests and diseases, tomatoes are a perfect addition to any container garden if you don’t have space for them in your raised beds.
In this article, we share our top tips for growing tomatoes in containers.
*Note: This article will provide tips for tomatoes grown in soil-like media outdoors, not indoor hydroponic growing.
Choose The Right Variety
Whether you are starting your own seed or buying a plant at a nursery, choosing the right variety and type is critical. The number of tomato varieties is vast, but they can all be broken down into two types – determinate and indeterminate.
Before you invest time and energy in growing your own container tomatoes, carefully read the seed variety description or plant tag at the nursery to choose the correct type.
Do you want a constant stream of fresh tomatoes all summer long? Indeterminates grow and produce continually throughout the season. Indeterminates can be successful in containers with proper pruning and support (see below).
Their wide range of flavors, textures and colors include most cherry tomatoes and heirloom “big boy” varieties. Keep in mind that cherry tomatoes tend to be very prolific producers, while big-fruited heirloom varieties will reward you with fewer large fruits.
Many heirloom and cherry type plants can become huge, and if space is at a premium, seek out varieties that have been specifically bred for containers. These container-types will be much smaller statured plants and still prolific. However, since container-type variety breeding is relatively new, you may have less choice of color and size of tomato.
Dreaming of canning a big batch of salsa? Determinate tomato varieties are sometimes referred to as “bush tomatoes.” They include most roma and “San Marzano” types, which are best for processing due to their lower water content in the fruit. Indeterminates set their fruit all at once, with a few stragglers or a small second flush after the first harvest.
Determinate tomato plants tend to be smaller, more compact plants than indeterminates, which sounds like a plus for containers. However, if you only have space for one tomato plant, choosing to plant a determinant is akin to putting all your eggs in one basket.
One determinate plant also may not provide enough tomatoes to can a batch of salsa. If you intend to preserve the harvest, choose determinants only if you have enough space for multiple plants.
Assess Your Space
Keep in mind how big the plant will be when it is full grown. Full grown cherry or heirloom tomato plants can be enormous, especially when they are well cared for.
Depending on the variety you grow, you should plan for at least 5 feet of plant growth vertically, and 2 feet on either side of the plant (4 feet radius). Compact or “dwarf” varieties are available and much more manageable in small spaces.
Decide how much space on your patio or yard you can devote to the plant. Make sure you have access to reach all sides of the plant for pruning and harvesting. If you have a tight spot such as a balcony, put the pot on a tray with casters (before planting!) so you can turn it if you need to.
Consider Sun Exposure
Is your patio east facing? West facing? How many hours of direct sunlight will there be? Tomato plants need at least 8 hours of sunlight to thrive, and prefer bright, full sun. Giving your plant east facing morning light is best, since it helps dry morning dew from the plants and it is not as hot as afternoon sun.
If afternoon sun is all you have available, you can still grow container tomatoes, but expect to water more frequently and keep an eye out for disease.
If your tomato is exposed to hot sun from dawn to dusk, water regularly and be especially vigilant that your pot does not dry out completely. Just remember, tomatoes are not veggies that grow well in the shade. they need plenty of bright, direct sunlight.
Choose the Right Container
Pick the biggest container with drainage holes that your space and budget allow. A 14” pot is the minimum recommended for container-grown tomatoes, and bigger is better. A big pot allows for more root growth, resulting in a larger, healthier plant with more tomatoes!
Terra cotta pot
Terra cotta pots provide a warm, rustic ambiance to any patio and are relatively inexpensive. However, large ones will be extremely heavy when filled with a full grown tomato, so plan to leave them in place the entire season, or place them on casters prior to planting. Since terra cotta clay wicks moisture from the potting soil, you may find the you need to water often.
Decorative/glazed ceramic pot
Decorative/glazed ceramic pots are another beautiful option that can be reused for many years. Like terra cotta, they are very heavy. However, the glaze helps reduce the water-wicking effect of terra cotta so you may have to water less. Be sure to choose a decorative pot with drainage holes.
Plastic pots are very budget-friendly, especially since you need a large pot. Their lightweight allows you to move your plants more easily if needed. Also, most plastic pots help the soil retain water longer. The exception is black plastic – which heats up in the sun and will increase evaporation – so you may be watering frequently. Plastic pots also make great liner pots for inside a decorative metal or ceramic pot.
Metal pots can offer more attractive and lightweight options, however, metal is apt to corrode if planted directly. They can also absorb the sun’s heat very effectively and may heat-stress the plant roots. Use a plastic or fabric liner pot when planting into any metal pot. Ensure the metal pot also has drainage holes, or drill them yourself.
Another, relatively new alternative for container growing is to use fabric pots, which are available in all sizes. Made of a sturdy poly felt-type fabric, these drain well and fold up when empty. The black fabric is unassuming, though is not as attractive as terra cotta or glazed clay. Fabric pots also make great liner pots when placed inside a clay pot.
Pick The Right Soil
Choose a potting soil that is specifically formulated for container planting. Potting soil should be composed mainly of a “soilless” media such as coir or peat moss, and perlite for proper drainage. Be wary of adding too much compost to the mix, or buying a mix that is too heavy with compost, as it may cause poor drainage. Good potting soil for containers should feel light and airy, not sticky and dense.
Potting soils are available with or without fertilizer and either will work for container growing. If buying potting soil that includes fertilizer, be sure to read the label. It should specify which type of plant the fertilizer is best for. If your potting soil does not include fertilizer, mixing an all purpose vegetable fertilizer or compost in before planting is a good idea. Follow the directions specified on the label.
Do not use top soil, pure compost, composted steer manure, or any other bagged soil in place of potting soil. Doing so will result in poorly draining containers that invite root rot.
Use a Trellis Before The Plant Grows
Tomato plants grow quickly, and the easiest time to install a trellis or support system is when you plant! Plants without support will flop over, risking stem breakage, and be difficult to harvest. Classic, round tomato cages will work fine.
Choose the largest size available that fits in your pot. Bamboo, wooden, or plastic stakes with garden twine can be used instead of a cage, but require “stringing” as the plant grows throughout the season.
Homemade cages built from “hog-panels” or “hog-fencing” are a great option for the committed DIY-er growing in an extra-large container. Cut pieces in the length of the diameter of your container. Create a circle with the fencing and wire the ends together. Drive plastic or wood stakes deep into the soil and attach the hog-panel cage to the stakes to keep them vertical.
Tomato varieties labeled container types may not need extra trellis or support at all. Some even come with a small plastic cage.
Plant at The Right Time
It may be tempting to plant your tomatoes in pots outside as soon as the weather warms. However, tomatoes are not frost hardy, so one night below 32 degrees will kill them. Wait until your location’s frost-free date has passed and the night temperatures are safely in the 50s to set your plants outside.
Container-grown plants need more water than in-ground plantings. Full, deep watering is preferable over frequent, small amounts of water. How often you need to water depends on many factors – the size of the plant, the size of the pot, and day and night temperatures.
To test if your plant needs water, insert your finger down the 2nd knuckle. If the soil feels dry, it is time to water. Water enough until water runs out of the bottom of the pot. Try to only water the soil and not the leaves of the plant, since water on the leaves encourages disease.
Be cautious of over-watering. Soil that stays continually wet will encourage root rot, where the plant is starved of oxygen. Over-watered plants will look wilted and thirsty – and they are! Their roots have lost the ability to take up water and nutrients due to being water-logged. The soil needs to dry out somewhat between waterings to avoid root rot.
Tomatoes need a balanced fertilizer up until flowering. If the potting soil you used does not already have fertilizer, it is best to mix in a balanced fertilizer prior to planting. Don’t fall for the myths, like using coffee grounds directly on your tomatoes.
Follow the application directions listed on the bag. If you want an organic fertilizer, look for an “OMRI approved” designation, which ensures that the fertilizer is organic.
At flowering, use a high potassium fertilizer and reduce the nitrogen. Most tomato-specific fertilizers follow this ratio. Be wary not to over-fertilize tomato plants with nitrogen at any point in the season, as too much nitrogen will result in leafy growth and little or no fruit, and splitting of green fruit.
Prune Throughout The Season
If you choose to plant any indeterminate variety other than a dwarf, container-specific variety, you will need to prune your tomato plant throughout the season. Pruning helps control growth and improves the quality of fruit.
Start by observing your plant. Look for mini-shoots popping out of the plant nodes (where the leaf grows from the main stem). These are called suckers. If all of the suckers remain on the plant, they will overtake the main stem and become unwieldy.
Choose one or two suckers to keep besides the main growing stem, or leader. Remove the other suckers using sharp, clean pruners, or (if the suckers are small enough) your fingers to pinch them off. Be careful to not remove the leader, as it can look like a sucker. Keep removing suckers as the season progresses to keep the size of the plant in check.
Watch Outside Temperatures
Tomatoes are sensitive to temperature. If your plants are not setting fruit and dropping their flowers, night temperatures below 50 degrees fahrenheit may be to blame. Tomatoes also will not set fruit well if day temperatures are above 90 degrees fahrenheit.
Observe and modify the microclimate of your container-grown plants to help your tomatoes thrive. For example, move your plants closer to the house or structures to increase heat and block wind, or further away to reduce warmth and increase air circulation.
Tomatoes are best harvested regularly as they ripen. For best flavor, let the fruit ripen completely where the tops or “shoulders” of the fruit are no longer green. Over-ripe fruit tends to split and cause a sticky, wet mess.
If you are expecting a large rain, harvest all fruit that is ripe and half-ripe to save it from splitting with too much water. The green-shouldered fruits will still ripen on your counter!
Remove all split, rotting, and diseased-looking fruit throughout the season. Fruit with visible fungi or mold is best not composted, to reduce the spread of pathogens.
Avoid harvesting tomatoes when the plant is wet from morning dew or after watering. Wet leaves encourage pathogens so working in the plant while it is wet may spread disease.
Enjoy Your Harvest Post-Freeze
One cold frosty night in the fall can spell the end of your container-grown tomatoes. If freezing night temperatures are expected, harvest any tomatoes you’d like to keep. Those with even a touch of color will eventually ripen on the counter.
After a few hard freezes, you will have a large, dead tomato plant on your patio! Using a pair of garden shears, prune it down to small pieces and dispose of it in a garden waste bag. If your plant has been disease free, composting in your home compost pile is also an option.
Growing tomatoes in pots is a great way to grow your own food and enjoy beautiful, productive plants without a garden. With a bit of planning, attention and care you can enjoy fresh, flavorful tomatoes all through summer as long as you follow these key tips:
- Choose an indeterminate or container variety
- Assess your space and plant with the end in mind
- Consider sun exposure
- Choose the right container
- Use the right potting soil
- Put up a trellis before the plant gets big
- Plant at the right time
- Water regularly
- Fertilize properly
- Prune it
- Pay attention to outside temperatures
- Harvest regularly
- Enjoy your harvest post-freeze
If you follow these tips you’ll be on your way to eating fresh, homegrown tomatoes this summer!