• Annuals and perennials. Long-blooming annuals and perennials provide a good source of cut flowers. Try alstroemeria, coreopsis, cosmos, gaillardia, gloriosa daisy, lavender, Limonium perezii, lisianthus, Mexican sunflower, purple or white coneflower, scabiosa, Shasta daisy, yarrow, and zinnia.
• Begonias and dahlias. These summer favorites provide a long season of bloom. Dahlia flowers come in many shapes and sizes; plants range from 1 foot tall to 6 feet tall or more. Tuberous begonias are either trailing (good for hanging baskets) or upright (for beds or pots). Flowers of both types come in a range of colors from pastel to vibrant.
• Hummingbird plants. One way to attract hummingbirds to your garden is to grow the nectar-rich plants that are their food sources. Tubular flowers of blue, orange, pink, purple, and red are their favorites. The best choices include abutilon, agastache, alstroemeria, bee balm, cestrum, cleome, coral bells, fuchsia, honeysuckle, lion's tail, penstemon, red-flowered perennial lobelia, salvia, and zauschneria.
• Vegetables. May is prime time to plant heat-loving vegetables such as beans, corn, eggplant, melons, okra, peppers, pumpkins, squash, and tomatoes. Sunset climate zones 1, 2, 17: Grow short-season varieties and plant through black plastic. In cold climates, spread floating row covers over vegetables to give them extra warmth and to protect them from late-spring frost.
• Wasabi. Zones 15 and 16 (with protection), 17: This cabbage relative is familiar to fans of Japanese cuisine as the spicy, head-clearing condiment that accompanies sushi. The green paste is made from the root of Wasabia japonica, an evergreen plant with edible, plate-size leaves. Planted from seed, it takes 18 to 24 months to produce a crop; that's why the frost-tender plants are best suited to cool-summer, frost-free climates (zone 17). They'll survive with protection in slightly colder zones, but if the crown freezes, they'll defoliate at 28°, and roots will die. Grow wasabi in cool shade and moist soil. Mulch in winter and protect with floating row covers if frost is predicted. Plants and seeds are available from Pacific Farms ( www.freshwasabi.com or 800/927-2248).
• Watermelons. These succulent summer fruits are fat-free and highly nutritious; they contain about 40 percent more lycopene (a powerful antioxidant associated with reduced risk of certain cancers) than raw tomatoes. Seedless watermelons tend to have the most lycopene. Red, ripe flesh is the best indicator of lycopene content. Two seedless varieties to try are 'Everglade' (11-14 lb.) and 'SweetHeart' icebox melon (8-10 lb.), available from Park Seed ( www.parkseed.com or 800/845-3369).
• Stake perennials. To support plants as they mature, install enclosed hoops or square stakes now so new foliage can grow up through the openings. Once plants are bushy, these stakes are difficult to install without damaging foliage.