WHAT TO DO IN YOUR GARDEN IN JULY.
* DRESS UP PERENNIAL BEDS.
When spring-blooming perennials such as bleeding heart, fernleaf peony and Oriental poppy go dormant in summer, cut off their yellowed foliage and fill the gaps with container-grown annuals. Dig the planting holes for the annuals off to the side of the perennials, being careful not to disturb their roots.
* REPLACE COOL-SEASON ANNUALS.
Clarkias, Iceland poppies, pansies, and stock can't stand intense summer heat. When they start looking ragged, pull them out and replant beds and containers with heat-tolerant annuals such as gazania, globe amaranth, gloriosa daisy Madagascar periwinkle, marigold, moss rose, petunia, sunflower, and zinnia.
* BE KIND TO BLUEGRASS LAWNS.
When temperatures regularly exceed 90[degrees], bluegrass goes dormant and turns brown if it does not receive adequate moisture. During heat waves, water every other day to prevent stress to the grass.
* CARE FOR CONTAINER PLANTS.
In really hot weather, check containers daily and water when they start to dry out. Foliar-feed container plantings with a liquid fertilizer weekly. If annuals become leggy; Cut their stems back by half to renew their vigor and restore their shape.
* DIVIDE TALL BEARDED IRIS.
The best time to divide overcrowded clumps of tall bearded iris is six weeks after they finish blooming. Toss out all old rhizomes and replant only healthy new fans. Irises are heavy feeders, so before replanting dig in a bucketful of compost or well-rotted manure and a handful of balanced fertilizer.
* APPLE MAGGOTS.
These pests damage apples by tunneling into the ripening fruit. Instead of spraying insecticide, hang one or two traps--red balls coated with a sticky product formulated to trap insects--in each apple tree.
* POWDERY MILDEW.
One warm, humid summer day is all it takes to trigger an outbreak of powdery mildew, a fungal disease that causes leaves to look as if they have been sprinkled with talcum powder. To prevent infection, spray plants that have succumbed to this disease in previous years with liquid sulfur or a fungicidal soap product every 7 to 10 days from midsummer through autumn.
* SPIDER MITES.
Leaves that become coppery or yellow and curled in midsummer may indicate an infestation of spider mites. Close examination with a hand lens will reveal these tiny tick-shaped pests and their webs, Blast spider mites off plants with a strong jet of water from the hose or spray with summer horticultural oil. To help prevent future infestations, rinse foliage with water once a week from midsummer until the first hard frost.
* TOMATO HORNWORMS.
These chubby 3-inch-long caterpillars can decimate a tomato plant within a few days. They are easier to spot early in the morning, when they can he found feeding at the tips of stems. Handpick the caterpillars or spray plants with Bacillus thuringiensis.