What to do in your garden in May

Sunset, May, 2004

SHOPPING

* Rhododendrons. If you're looking for a specific flower color to go with other plants in your garden, shop for rhododendrons while they're blooming this month. These Northern California nurseries sell a wide range of choices: Singing Tree Gardens in McKinleyville (open Wed--Sat or by appointment; www.singtree.com or 707/839-8777) and Westgate Gardens Nursery in Eureka (closed Wed; 707/442-1239).

* Summer poinsettia. This showy annual isn't related to poinsettias sold at Christmastime (Euphorbia pulcherrima); it's a type of amaranth (Amaranthus tricolor). The upper third of this 4- to 5-foot-tall foliage plant produces a crown of brightly colored leaves reminiscent of the popular holiday plant. 'Aurora' has yellow upper leaves, 'Illumination' is gold and crimson, and 'Perfecta' has a yellow-and-scarlet crown. Shop for plants at nurseries, or buy seeds from Park Seed (www.parkseed.com or 800/845-3369). Plant them in the back of a border for vivid color from summer into fall.

PLANTING

* Herbs. For fresh flavorings this summer, plant basil, chives, cilantro, oregano, parsley, rosemary, sage, and thyme. To stretch the harvest season, set out transplants of cilantro every two weeks, basil every three to four weeks. To keep woody herbs (oregano, rose-mary) producing fresh green growth, snip off stem tips regularly once plants are well established; use the prunings for cooking. Shear back plants when flower buds form but before they open. Sunset climate zones 1, 2: Wait to plant basil until the soil is warm (at least 65[degrees]).

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* Tomatoes. Zones 7-9, 14-17: It's too late to start from seed, but you can still buy seedlings at nurseries. Plants should be stocky, not leggy, and a rich green color. Plant tomatoes deeper than they were growing in the container. Pull off the lowest one or two sets of leaves, then dig a planting hole deep enough so the stem is covered to just below the remaining bottom set of leaves; roots will form along the stem. Zones 1, 2: Plant in mid- to late May after last frost has passed.

MAINTENANCE

* Apply iron chelate. If foliage on azaleas, camellias, citrus, and gardenias is yellowish with green veins, the plants need iron. Use iron chelate (according to label directions) or, if the plants also need nitrogen and other nutrients, apply a complete fertilizer containing iron chelate.

* Feed and mow lawns. Fertilize warm-season grasses like Bermuda with a high-nitrogen formula; give fescues and other cool-season grasses one last feeding until fall. Mow more frequently but always lightly, never taking off more than 1/4 of new growth at a time. Set blade height to between 2 and 3 inches.

PEST CONTROL

* Combat pests. Knock aphids off with a strong stream of water from the hose or spray them with insecticidal soap. Handpick or set out bait for earwigs, slugs, and snails. Spittle-bugs (look for white foam in stem crotches) are harmless in small numbers; knock them off with a blast of water. If most stem crotches are infested, spray with insecticidal soap, adding a lightweight summer oil to improve effectiveness. Protect beds from gophers and moles by burying wire mesh before planting.

RELATED ARTICLE: TIP FROM THE TEST GARDEN

Deadhead technique

Here's how to coax more blooms.

* Shasta daisy. After topmost flowers fade, cut the stem back to a side blossom, bud, or leaf. When no buds remain, cut the whole stem down to the base.

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* Delphinium. After the season's first flower spike finishes blooming, cut it back to the base. This encourages formation of new spikes for late-summer bloom.

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