Grow what you like to eat and select vegetables for taste, ornamental value, compact size and quick maturity, says Renee Shepherd of Renee's Garden Seeds. The pioneering Californian gardener has tested countless vegetable varieties from seeds she has collected from around the world.
"Vegetables in containers are entirely dependent on you, so if you want them to keep pumping out fruit, water consistently and feed them once a month with an organic fertilizer," she says. And no matter what you decide to grow, start with fresh sterile potting mix, which holds air and nutrients better than last season's worn out soil.
Here are her five best bets for veggie plots in pots.
Baby leaf lettuce, also called mesclun or cut-and-come-again salad greens, are quick-growing lettuce mixes that mature in about 35 to 40 days. "Sow seeds thickly for a uniform crop," says Shepherd. When they're 10 to 12 centimetres tall, harvest the greens for salads, leaving about 2 cm at the base of the plants. They'll quickly regrow for a fresh, season-long harvest.
The best edible flowers for container gardening are nasturtiums, says Shepherd.
"They mound up, drape over the edges of pots and they're attractive to hummingbirds, too," she says. Both flowers and leaves have the sharp, peppery taste of watercress with sweet honey notes. Shepherd uses both in salmon or shrimp sandwiches, along with a dollop of Dijon mustard.
Select the colourful "Rainbow" or "Neon" varieties of this attractive spinach-like green, planting them 15 to 20 cm apart so they have plenty of room to grow to maturity, advises Shepherd. "When they have seven or eight leaves, pick off the outer leaves to regenerate more," she says. Shepherd uses these harvested chard leaves in stir-fries or she sautées them in olive oil and garlic and serves them with shavings of Parmesan cheese.
Shepherd has discovered two varieties of tomatoes that do well in containers. Both "Superbush" and "Stupice" are compact plants that grow no more than 60 cm to about a metre high, making them easier to manage in containers than most bushes that can become unruly when grown in pots. "They need only a short stake or cage for support," says Shepherd, "and they mature early, producing full-size fruit." Mulch with 5 cm of organic material to help keep moisture in the soil, she says, but to prevent blossom end rot, cut back on watering by about one-third once the plants have set fruit.
Garden-variety zucchini or summer squashes can get out of hand in a garden plot, but "Astia" is a compact variety that "doesn't get huge and doesn't take over the world," Shepherd says. A non-rambling bush variety from France, "Astia" produces quick-maturing fruit that can be easily harvested from the base of the plant. It also has attractive, silvery-green foliage.