Growing Vegetables and Herbs in Containers

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You can grow a miniature vegetable garden. Growing vegetables in containers is an easy and pleasurable way to garden if you live in an apartment, town house, or condominium. A sunny balcony, patio, courtyard, porch, doorway, or windowsill is all you need to get your small garden growing. Most vegetables and herbs will succeed in containers. In fact, your ability to move a container from shade to sun and from a chilly location to a warm location almost assures success.

Choosing a container. Containers may be almost anything that suits your fancy: plastic or clay pots, plastic or wooden window boxes (redwood or cedar is durable and slow to deteriorate), tubs, bushel or wire baskets, or barrels. I’ve even seen vegetables growing in old watering cans and garden boots. You can improvise with all sorts of containers depending upon which vegetables you want to grow.

Plastic pots are light weight and usually inexpensive. Molded polypropylene is popular–many with a clay pot look to them. (These will insulate the soil from cold better than thin plastic.) Clay and terracotta pots are more expensive but very attractive. Clay and terracotta need more frequent watering if a plastic liner is not used. Glazed pots also are attractive, but double check to make sure they have drainage holes. Wooden boxes, tubs, and half barrels are a good choice where freezing weather is common. Make sure wooden containers have drainage holes and once planted, don’t let them dry out or they will crack or lose their form.

Container size. Your best choice is to choose as large a container as possible. Beans, cucumbers, green peppers, and tomatoes require five-gallon containers (dwarf varieties will get by in two-gallon pots). Radishes, lettuce, scallions, cress, parsley, carrots, and chives, and other herbs flourish in a container six inches deep and about six inches wide. A single small vegetable such as lettuce or spinach will grow in a six inch pot. A 12 inch pot will accommodate four lettuce or spinach plants. An 18-inch pot will hold as many as ten herbs. Avoid shallow containers that will cramp roots and can either dry out quickly or become waterlogged. Perforate the base of any container so excess water will drain away. If you are using a container that’s been used before, be sure to wash it thoroughly before planting.

Soil mix for containers. Buying pre-mixed potting soil is the easiest way to fill your container. Bagged potting mixes comes in several sizes. Garden centers and most hardware stores sell potting mixes–which is usually a multi-purpose soil or compost. If you have good growing soil in your garden, you can use it: add half garden soil and half multipurpose compost or sphagnum peat moss to make your own mix. (Soil from the garden alone is almost always too dense for container plant growing.)

Place a layer of peat or sterilized bark at the bottom of the container over the drainage hole to keep your potting mix from washing away. Next add a layer of compost and then the potting mix. Place large containers–such as tubs and half barrels–in their final position before filling them with soil. If you plan to move large containers during the year set them on wheels or rollers. Fill the container to within 1 inch (2.5 cm) of the top.

Water, weeding, and care. Container plants almost never need weeding, but you will need to water more frequently. Container soil should be moist to the touch, but never soggy: too much water rots roots. Water immediately after planting to wash potting mix from the foliage, after that, use a watering can with a fine-rose nozzle to water so as not to disturb the planting mix. (If watering indoors, use a kitchen measuring cup.) Another technique is to water from below, by placing the pot in a watering tray and allowing the water to wick up into the pot for an hour or two. It’s best to water early or late in the day so that the rays of the sun do not damage wet leaves. In warm weather be sure to check your containers every day to make sure they are not dry. Water whenever the soil is dry to a depth of 1 inch. Don’t let containers dry out; that will interrupt quick growth which is essential to container vegetable gardening and can cause plants to drop blossoms and fruits.

Whenever you water look for weeds and remove them and trim away any dead leaves or debris and check for insect pests. Most insect pests can be stopped early with a spray of insecticidal soap–a light squeeze of dish soap in a spray bottle. Twice during the growing season give your container vegetables a feeding of compost tea; this should be enough to replenish the nutrients they draw from the soil. At the start of the next season, it’s best to begin again with fresh, nutrient-rich soil.

What to plant. Choose compact, dwarf, or fast maturing vegetables for your container garden. Leafy vegetables such as lettuce, spinach, chard, green onions, and cabbage can thrive with just five hours of sun each day. Root vegetables such as radishes, carrots, and beets need an hour or two more. Fruiting vegetables require the most sun and warmth; cucumber, eggplants, peppers, and tomatoes insist on at least 8 hours of full sun each day. The same is true for beans. Tomatoes, peppers, and cabbage plants are especially recommended to the beginner. Herbs are easy to grow in containers: try chives, parsley, basil, dill, rosemary, sage, summer savory, tarragon, and sweet marjoram.

Look for vegetables specifically recommended for container gardening–these are compact or dwarf vegetable varieties such as Little Ball beets, Short ‘n Sweet and Little Finger carrots, Tom Thumb and Salad Bowl lettuce, and Tiny Tim or Pixie tomatoes.

Container gardening is a good way to practice vertical gardening. Cucumbers, beans, peas, and tomatoes can be trained on a trellis. Place the trellis in your container before you fill it with soil and plant. Choose a larger container that is broad based to avoid tipping when vining crops reach maturity.

Planting combinations. You don’t have to grow just one vegetable in a container. Edible flowers such as pot marigolds and violas can be grown with lettuce. Grow leaf lettuce with parsley, chives, and coriander. Lettuce, onions, beets, and garlic can be grown in a large container with broad beans. Small-fruiting peppers such as ‘Tabasco’ or ‘Serrano’ will make a colorful patio container. Grow tomatoes and basil or thyme together. Ruby chard in its own pot is a colorful accent for any deck.

Keep the garden going. For an extended harvest, make small sowings of different vegetables every three to four weeks during the growing season. Leafy crops can be harvested cut and come again every couple of weeks. To extend the tomato harvest plant two patio varieties a month apart. When the weather turns cold, your container crops can be moved to a warmer location or you can use large clear plastic bags draped over wire frames to form a mini-greenhouses that will keep plants growing several weeks after the first frost in autumn. Most vegetables will not grow in the house over the winter; they require a special combination of heat, sunshine, and humidity that is best found in a greenhouse or cold frame. But herbs can be grown indoors over the winter. Expose herbs to gradually warmer temperatures on a porch or in the garage before bringing them into the house for the winter. Herbs can be placed in a sunny window to be enjoyed almost indefinitely.

This is Part I of a HarvestToTable.com three-part series: read Part II: Vegetable Varities for Container Growing. Part III of this series is called “Dwarf and Miniature Vegetables for Containers.”