What to do in your garden in August
Late-summer to fall color Choice perennials for late-season color include aster, chrysanthemum, coreopsis, daylily, gaillardia, gaura, lavatera, Nemesia fruticans, rudbeckia, Russian sage, salvias (such as Salvia elegans, S. guaranitica, S. mexicana 'Limelight'), and verbena for sun. In the shade, plant Japanese anemone.
Late tomato crop If you want to try for fall or winter tomatoes, look for early-fruiting varieties that originated in colder climates. Most are determinate bush types rather than indeterminate vines. Start with seedlings. Good choices include 'Bush Early Girl', 'Glacier', 'Oregon Spring', 'Siberian', and 'Stupice'.
South African bulbs Freesias, ixia, sparaxis, and other South African bulbs ― the best bulbs for naturalizing in Southern California ― begin appearing in nurseries this month. Shop early for best selection; plant immediately.
Winter crops Coastal ( Sunset climate zones 22-24), inland (zones 18-21), and high-desert (zone 11) gardeners can start seeds of cool-season vegetables in flats. The seedlings will be ready to transplant to the garden in 6 to 8 weeks. Traditional choices include broccoli, brussels sprouts, cabbage, cauliflower, chard, kale, lettuce, peas, and spinach. Feeling adventurous? Grow broccoli raab, Chinese broccoli, mâche, or sorrel. Johnny's Selected Seeds (877/564-6697) is a good source for these and other specialty vegetables.
Dethatch warm-season grasses Late summer is the ideal time to dethatch Bermuda, Kikuyu, St. Augustine, or zoysia grasses because they grow back quickly. If thatch is very heavy, don't get rid of it all at once: Dethatch lightly and repeat in a month. Unless you have a very small lawn, rent a dethatching machine.
Irrigate trees and shrubs Give these plants a deep soaking, even if they're regularly watered by a sprinkler system (see Tip from the Test Garden). Set a hose to deliver water slowly into a basin around the plant, or lay a soaker hose around the plant along its dripline. Run the water until the soil is soaked to a depth of 12 inches for shrubs or up to 24 inches for trees. Check moisture penetration by digging down with a trowel.
Mist plants occasionally Misting plants with a hose on hot days gives them a lift, keeps foliage clean, and chases away pests like spider mites. Even native and drought-tolerant Mediterranean plants benefit.
Protect against brushfires If you live in a fire-prone area and haven't done so already, remove all dead limbs and leaves from trees and shrubs, particularly those that grow near your house. Keep tall grasses and weeds cut down to stubble; remove any woody vegetation growing next to structures. Create an evacuation plan. Visit www.sunset.com/fire for more tips.
Water some plants frequently Container plants and hanging baskets dry out rapidly in late summer, so daily soakings may be necessary. Water annuals and vegetables often as well. This time of year, shallow-rooted trees like avocado and citrus need irrigation at least once a week inland; along the coast, every other week may be sufficient.
TIP FROM THE TEST GARDEN
How to water trees
Build watering basins Mound soil berms around young trees to concentrate water on the root zone. Form the main berm just outside the tree's dripline; make a second berm 4 to 6 in. from the trunk to keep water off it.
Use soaker hoses These porous hoses ooze water along their length. For a large tree, coil a 50- or 100-ft. hose out to the dripline.
Irrigate the roots Deep-root irrigators are hose-end devices with forked or needlelike shafts that inject water into the root zone of a mature tree, 12 to 24 in. below the surface. Insert the shaft 12 in. or deeper into the soil along the dripline; after watering in one spot sufficiently, move the irrigator to other spots along the dripline.