- Author: Pat Hitchcock and Jim Murphy, UC Master Gardeners of Napa
In a restricted area, such as an apartment complex or a small, confined yard, containers may be the ideal way to raise vegetables. Pot selection, container soil, container positioning, sunlight and heat deflection from walls or fences all contribute to a successful growing experience.
You can use many different kinds of containers, such as wooden planters, clay pots, plastic buckets or even plastic bags filled with planting mix. They must have drainage holes. If you are placing containers on a wooden surface, such as a deck, reduce the possibility of rot by raising the containers on small blocks to allow for air circulation.
Be sure your containers are deep enough for the crop you want to grow. Six to ten inches is sufficient for shallow-rooted plants like arugula, basil, chives, lettuce, green onions, radishes and mizuna. With a deeper pot, 10 to 15 inches, you can try carrots, celery, Chinese cabbage, garlic, leeks, Swiss chard and patio tomatoes.
Go for 18- to 24-inch-deep containers if you want to try beans, broccoli, kale, peas, peppers and short-vine (determinate) tomatoes. A container 20 inches in diameter and 18 inches deep will give you plenty of room for several small lettuces or for one pepper or tomato plant.
The planting medium needs to be both porous and moisture retentive. Because you may need to move your pots occasionally, it also needs to be lightweight. Garden soil is too dense and heavy. A good-quality potting soil will contain compost and nutrients for plants, plus vermiculite or perlite for drainage and peat or coir for holding moisture.
Finding the perfect place for your containers may be the most challenging part. Leafy vegetables such as lettuce need four to six hours of sunlight daily, but fruiting vegetables like peppers, beans and tomatoes need eight hours. An area near a wall that reflects sunlight can be too warm for some plants.
Container soil can get a lot warmer than the ground. Try shading the containers themselves if they are in a warm spot, while allowing the growing plants to get all the sunlight they need.
Container plants require more frequent watering than plants in the ground, and they also need more frequent fertilizing. Most commercial potting soils include fertilizer to get plants off to a good start. After six weeks or so, start fertilizing every other week with a half-strength liquid fertilizer formulated for vegetables or container plants. Nurseries sell organic and inorganic types. Check label directions for the suggested dilution, then double the recommended amount of water to get a half-strength solution.
For container gardens that are always on view, consider the many vegetables that are ornamental. Look for colorful versions of lettuce or Swiss chard, for example. A combination of leafy lettuces, blooming chives and a viola could produce an instant salad mix in a cool location. For the warm season, try a patio-type tomato with sweet basil at the base. Nurseries often have pots with such pre-planted combinations, but it's fun to create your own.
In April, the options for edibles are almost limitless. You can still start some cool-season vegetables, but it is also planting time for warm-season crops. The Napa Count Master Gardener website has several planting calendars in its “Healthy Garden Tips” section. Find that section under the “Gardening Resources” button on the left side of the home page.
Edible container gardens aren't limited to vegetables. Many perennial herbs do quite well in pots. Try thyme, oregano, marjoram and parsley. Edible flowers such as nasturtiums and violas also thrive in containers. Don't let lack of a garden plot keep you from the pleasure of harvesting your own edibles.
Tomato Plant Sale: U. C. Master Gardeners of Napa County will hold their fourth annual Tomato Sale and Education Day on Saturday, April 23, from 9 a.m. until sold out, in a new location at 1710 Soscol Avenue, Napa. Choose from 28 varieties, including heirlooms and new varieties in a range of colors. These healthy, Master Gardener-grown seedlings include types for fresh eating and for sauce.
Workshops: U. C. Master Gardeners of Napa County will hold a workshop on “Growing Tomatoes” on Sunday, April 10, from 2 p.m. to 4 p.m., at the Yountville Community Center, 6516 Washington Street, Yountville. The workshop will focus on techniques for a successful harvest, including soil temperature requirements; tomato types; care and fertilizing; support choices; and integrated pest management. Register with the Parks and Recreation Department at
707-944-8712 or on its web site.
The “Growing Tomatoes” workshop will repeat on Saturday, April 16, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension office, 1710 Soscol Avenue, Napa. On-line registration (credit card only); Mail-in/Walk-in registration (cash or check only).
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.