By Cyndy Crist
A rectangular space with neat rows of plants in a backyard or community garden – this may be the image that first comes to mind when you picture a vegetable garden. But for many of us in urban settings, this kind of garden isn’t an option because we may lack sufficient space or sun to grow vegetables. And you don’t have to live in an urban area to lack the time or physical ability to tend such plots. Happily, a wide array of edibles can be grown in containers of various shapes and sizes. With a little attention to the choices of plants, pots, and growing medium as well as growing conditions, anyone can produce tasty vegetables in containers. Here are some tips to help guide your planning.
Why Grow in Containers
A lack of space for a vegetable garden isn’t the only reason to grow edibles in pots, although it is a big one. Some of us, especially in older urban neighborhoods, have little space that gets the 6-8 hours of sun daily that most vegetables and herbs require, but we probably have small, sunny spots here and there big enough for a container or two. And we may be able to take advantage of shifting sunlight over a day or the season by growing edibles in movable containers.
In addition, growing vegetables in a container or two lets those who have little time to spend tending plants or who don’t want to devote much energy to gardening grow their favorite vegetable or herb. Finally, individuals with limited mobility or strength can often manage to tend a few plants in pots or containers placed on raised surfaces.
There are also a few botanical benefits for growing edibles in containers. Karl Foord from the University of Minnesota Extension Service has identified three:
They’ll be less accessible to animals that like to munch on them.
Growing in containers reduces soil-borne disease problems.
Vegetables grown in pots tend to suffer less from leaf diseases since the water on leaves in pots tends to dry more quickly.
Some have suggested that nearly anything that can be grown in a garden can also be grown in a pot. While that is generally true, you can increase the odds of success by carefully selecting what you grow.
Starting with tomatoes, many identified as the best choices for growing in pots are a dead give-away because of names that include words like patio, tiny, pixie, small, or toy. Specific varieties frequently mentioned as good choices for containers include Patio, Tumbler (a cherry tomato), Bush (Dorothy’s number one choice for containers), Fourth of July, Purple Cherokee, Toy Boy, Tiny Tim, Gardener’s Delight (an heirloom cherry tomato), Tumbling Tom, Beefmaster, and Silver Fir Tree.
For other types of vegetables, a little common sense and 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 but they’ll need 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. Just about any herb or salad green (lettuces, spinach, and other leafy greens) can be grown in containers and, in fact, well-placed pots of these edibles can make them handy to harvest for regular use in the kitchen.
When selecting pots for container gardening, there’s more to think about than color, shape, and design. At least three practical factors need to be considered.
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 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!
So, for those of you with little or no garden space to call your own, take heart. You can grow an array of fresh veggies on your patio, porch, balcony, or in any little sunny spot you may have. Just choose your pots and your plants wisely, water and feed them regularly, and make sure they get plenty of sun. If you do, they’ll reward you with tasty treats all summer long. Now, how easy is that!