For many people in urban settings, growing tomatoes and vegetables in containers or pots is necessary due to space constraints or lack of 6 hours of direct sunlight. Container gardening is also a preferred option if you live lack the time or physical ability to tend plants grown in the ground or in larger plots. The tips below focus on attention to the choice of plants, pots, and growing medium to help guide your planning.
Benefits of Container Growing for Edibles
As noted above, lack of space and lack of 6 hours of sun daily are two major reasons people choose to grow vegetables in pots. A few other benefits include:
- ability to move containers throughout the day to take advantage of shifting sunlight;
- raised surfaces for those with limited mobility or strength to manage tending the plants;
- plants are less accessible to animals who eat the leaves, roots or fruit;
- soil-borne disease problems are reduced or eliminated;
- it is easier to control the watering regime which can help with disease on leaves
Choosing Plants for Containers
With respect to tomatoes, all of them “can” be grown in pots but “determinate” tomatoes require much less staking and are therefore good candidates for container growing. Smaller tomatoes, like cherry tomatoes are also good choices for pots due to their small size and weight. Click here for details on the best varieties of tomatoes for container growing.
Beyond Tomatoes: Other Vegetables for Container Growing
For other types of vegetables, attention to growing habits will go a long way in making good choices. For example, some varieties of cucumbers and pole beans can be grown successfully in pots, as long as you provide good support for their vining habits.
Small to medium-sized root vegetables like radishes, carrots, turnips, and beets can be grown in containers, as can green onions, peppers, eggplant, and broccoli.
Most herbs are fairly easy to grow in containers, as long as they have access to sun. Salad greens can flourish in shadier areas and do not need large pots.
Selection of Pots
When selecting pots for container gardening, there are three main factors to consider.
Drainage is arguably the most important consideration. If you’re going to grow edibles in containers, your pot must have good drainage so that your plants never sit in standing water. Sitting water in pots will kill plants; it’s that simple. And don’t forget about the water that may run out of the bottom of the pot. If this water accumulates, you’ve defeated the purpose of drainage holes. Either make sure you can lift the pot and dump out any water that does accumulate in a pot tray or keep your pot raised an inch or more off the surface on which it’s sitting. You can also reduce the chances of root rot by putting an inch of gravel in the bottom of the pot to hold excess water away from roots. I know gardeners who put a layer of packing peanuts in the bottom of large containers to provide drainage and reduce the weight of big pots.
The kind of pot used is also important. You’ll want to keep a few things in mind before you make your choice. Wooden containers (half-barrels, for example) may offer a look, size, and shape that you like, but they will rot over time and need to be replaced. The porous nature of unglazed terra cotta pots will make it difficult to keep your pots sufficiently watered since water will evaporate through the pot’s surface. Better choices are pots made of nonporous materials like glazed ceramic, plastic, glass, and metal, though at the risk of sounding like a broken record, don’t forget that good drainage is essential.
Size is the third factor to consider. Most tomatoes require pots that hold at least five gallons of soil or potting medium, although some varieties can be grown in two gallon containers. Vegetables that remain smaller can obviously do well in smaller pots, though less than one gallon is generally not recommended except for herbs and small salad greens. A few plants have specific requirements. For example, carrots need to grow in soil that is at least two inches deeper than their mature length, and green beans need to be spaced at least three inches apart.
Choosing a Growing Medium
Many experts recommend using a soilless potting medium for container growing because it drains well and is lighter weight (especially important if your pots are large and require lifting or moving). With soilless mixes, however, it is especially important to fertilize your plants regularly, since these mixes generally contain fewer nutrients. If you choose to use potting soil, make sure that you use a sterile soil mix, not soil dug from your yard or garden. This will reduce or eliminate the chances of introducing soil-borne diseases into your containers. You can make your own potting mix with equal parts of soil, compost or peat, and either sand, perlite, or vermiculite, but again, be sure to use sterilized soil.
Planting Container Gardens
Planting containers is the easy part. Generally speaking, you’ll want to settle in your plants in pots just as you would in the garden. For most plants, this means planting them so that the level of the soil in the pot from which they’re being transplanted is at the surface of the soil or potting medium in the container. One exception to this rule is tomatoes, which can nearly always benefit from being planted so that the first set of leaves is below the soil line; this allows the tomatoes to grow additional roots and be both more stable and able to take up more water. And be sure to follow directions for spacing if you’re growing seeds or using more than one plant per pot.
Maintaining Container Gardens
A key factor for successful container gardens is watering. Because the soil in pots can heat up more quickly than soil in the garden and has less overall capacity to hold water, containers generally need to be watered daily. In fact, in especially hot and windy weather, you may need to water more than once a day. Some growers recommend that at least once each week you water deeply enough for water to run through the bottom of the pot, but be sure the excess drains away. As with gardens, you can help maintain moisture in your pot by putting a layer of mulch on the surface of the soil. Finally, if you are concerned about not being able to keep up with daily watering, you may wish to try one of the water-holding gels now on the market; these should be mixed into the soil at the time of planting.
Proper and sufficient feeding of container plants is also essential for plant health and robust production. For me, it’s easiest to use a time-release fertilizer like Osmocote Flower and Vegetable Smart-Release Plant Food, which should be worked into the soil at the time of planting in the amount recommended on the package. With this approach, a single application will carry you through the whole summer. However, there are many options for those who want to grow organically. Just be sure you choose a fertilizer that’s labeled for your vegetables and follow directions carefully for the correct amounts, method, and timing of application. I still remember an early attempt at container growing when I inadvertently “killed with kindness” the plants I had purchased because I used much too much fertilizer. That’s one lesson I’ve never forgotten!