What to do in your garden in May
This is the optimum time to plant bananas, cherimoyas, and other subtropical fruit in Sunset climate zones 21–24; avocados in zones 19 and 21–24; and citrus in zones 13–24. Try mandarinquats, a cross between kumquats and mandarin oranges, which have an edible rind like the former but a sweeter taste like the latter.
Leymus condensatus 'Canyon Prince', a native grass with silvery blue leaves, is a gorgeous but aggressive landscaping plant. To keep it in bounds, plant it in its nursery container. Cut away the bottom and the lower third of the sides. Position so that several inches of the container protrude aboveground; growing foliage will soon hide the pot. This technique also works with other rhizomatous grasses like Japanese blood grass (Imperata).
Shop for summer and fall bloomers like asters, coreopsis, reblooming daylilies, gaillardia, gaura, gloriosa daisy, heliotrope, lion's tail, penstemon, pentas, phygelius, purple coneflower, salvia, and stokes aster.
Set out cucumber, eggplant, melon, pepper, and tomato plants. Sow lima and snap beans, corn, cucumber, melon, and summer and winter squash. In the low desert, plant Jerusalem artichoke, okra, peppers, and sweet potatoes.
Nicotiana is sun-loving, easygoing, long-blooming, and it attracts hummingbirds. The salmon and lime hybrids are our favorites ― combine them with a dark blue flower, such as lobelia, to make them pop. You may have to search a little harder to find them instead of the more common pink, red, and white shades.
Summer-blooming vines, grown up a narrow structure, add color and height to even the smallest gardens. Choose a showy subtropical perennial, like the Mandevilla shown here; or morning glory, climbing snapdragon (Asarina), or another annual vine. Before planting, set in place a sturdy structure with enough height and heft to support your vine (adding a structure later is difficult). As shoots grow, train them to the support with self-gripping Velcro, plant tape, or twist ties.
Use tomato trusses, plastic supports that you slip over fruit-laden tomato stems to keep them from bending or breaking as the fruit ripens and grows heavy. It’s just what’s needed for ‘Mortgage Lifter’, ‘Oxheart’, and other beefy varieties. Available from the Natural Gardening Company.
If hibiscus, princess flower, and other subtropicals have become leggy and awkward, cut back by as much as half to reshape.
When foliage on garlic, bulb onions, and shallots begins to dry out on its own, that’s your cue to stop watering. The lack of water prompts bulbs to form the dry outer layers that allow them to be stored.
Examine your tomato foliage regularly for hornworms. The big green worms will be easier to spot if you sprinkle foliage lightly with water first; the motion of shaking off the water makes them more visible.
As the weather heats up, so do pest problems. To help identify what’s bugging your plants and find a solution, use the resource Master Gardeners rely on: the University of California Integrated Pest Management Program’s site.