Michigan State University Extension-Oakland County Monthly Garden & Landscape Guide August Use these tips to keep your landscape and garden in great shape throughout the year. Flowers Bulbs Draw up plans for fall planting. Remove dahlia side buds for bigger blooms. Remove bulblets from the leaf nodes of lilies that you want to propagate. Late in this month, begin preparing for fall bulb planting. Select a well-drained area in sun or partial shade. Clear the area of grass and weeds and dig in two to three inches of compost or manure. A fertilizer such as 12-12-12, bone meal, Bulb Booster or any other commercial bulb fertilizer should also be added at label rates. Annuals Take cuttings from coleus, geraniums, wax begonias, impatiens and fuchsia to grow indoors this winter. All cuttings may not form roots, so take more than you think you ll need. After taking the cuttings, remove all but the upper two or three pairs of leaves. Let the cuttings sit in the open for a day to cure. After dipping the ends in a rooting powder, stick in damp sand to root. Do not cover the cuttings. If growth appears pale and slow, use a water soluble fertilizer with phosphorus to improve growth and bloom. Pinch the faded flowers and seedheads from summer annuals so they ll keep producing new blooms until frost. Perennials Weed beds on a regular basis so desirable plants don t have to compete for water, nutrients or space. Beds need about one inch of water per week during dry weather. Plant peonies, iris and daylilies. Divide and replant peonies, iris and daylilies if you haven t done so for several years. For iris, lift plants and cut away root sections affected by borer or crown rot. Cut roots into sections, leaving one or two fans per section. Divisions can then be replanted or shared. Stake and tie tall dahlias as necessary. Remove some of the buds and thin the
side shoots to encourage dahlias to produce larger flowers. Cut back the tops of perennials as they die. Continue mildew prevention sprays on aster, tall phlox and Joe-Pye weed. Late this month, you can begin to divide and replant spring and summer blooming varieties. This is a good time to divide and transplant Oriental poppies. Remove spent blooms from dwarf astilbe, early aster, threadleaf coreopsis, Joe Pye weed, baby s breath, hosta, border phlox, false sunflower, tall phlox, and purple coneflower. Cut back old growth on delphiniums when new basal growth is observed. When dividing perennials, lift with a spading fork, being careful not to damage the roots in the process. Use a sharp knife to cut through the tough root mass. Most perennials benefit from division every three to four years; seven years for daylilies. Container-grown perennials can still be planted into early autumn. Roses This is the final month for live pruning on roses. No more pruning should be done after Labor Day; this includes deadheading. After Labor Day, spent blooms can be depetalled to maintain their attractiveness. The final granular or liquid fertilizer application, preferably a high potassium formula for cold hardiness, should be made around the middle of this month. Sprays for disease prevention should continue. You can still plant container roses this month. Fruits Begin the harvest of early grapes, early apples and fall bearing raspberries. Prune and destroy spring-bearing raspberry and blackberry canes that bore fruit this year. They won t bear again and they could be harboring insects or disease organisms. Do not put canes in compost pile. Monitor populations of aphids, European red mites and white apple leafhoppers in apple trees. Small fruits should receive an inch of water a week during hot and dry weather. Remove and destroy any brambles showing signs of mosaic virus. Pears are best ripened off the tree, so do not wait for the fruit to turn yellowish and soft on the tree. Harvest pears when color of fruit changes, usually from dark green to a light green, and when the fruit is easily twisted and removed from the spur. Propagate black raspberries, purple raspberries and dewberries by layering. Bury the tips of canes so that a few inches of growing tips are exposed. Allow to root until next spring.
A cover crop of oats between rows of raspberries will protect loose soils from winter erosion. Grapes and bramble fruits can still be planted. Continue harvest of day-neutral and everbearing strawberries. Keep strawberries, brambles, currants and gooseberries weeded to prevent competition for water and nutrients. Clean up and destroy fallen tree fruit on a weekly basis to reduce future problems with apple maggot, coddling moth and plum curculio. Herbs Leafy herbs can be harvested by cutting and dried by either hanging in bunches in a dark place or spreading on paper toweling and turning every couple of days until crisp. Herb gardeners will want to dig and divide their outdoor plants to bring indoors for the winter. If they seem a bit leggy after they are in the pot, snip the plant in half to promote new growth. This can be done with lemon balm, mint, chives and burnet. Mint, scented geraniums, lavender, roses, chamomile, yarrow and bee balm can be cut and dried for potpourri. Hang upside down in an airy and warm area until completely dry. Lawn Late this month, if necessary, you can start the fall treatment for white grubs. Establish a new lawn or renovate an old one between August 15 and September 15. M.S.U research has shown this to be the best time to start a lawn in Michigan. Seed bare spots in established lawns. To promote quick germination, loosen the soil before seeding, firm it afterward and keep newly seeded areas moist. Sow seeds of improved turfgrass varieties that are compatible with the grass already growing there and adapted to the growing conditions. If you don t know what s growing in your lawn, the rule of thumb is to use improved Kentucky bluegrass in sunny areas and a mixture of ryegrass and fescue in shaded lawns. You can lay sod at this time. To calculate your needs, determine your area and add 10%. Sod strips should be of even thickness and moisture with clean edges and a good root mat. Lay in a staggered pattern, like brickwork, and roll to put the roots in contact with the soil. Water daily until established. Trees, Shrubs & Vines Treat black locust and rose acacia for locust borers. The best time is when mountain ash fruit is ripe and pee gee hydrangea blooms are white. Avoid fertilizing trees and shrubs now. They would respond with a flush of late growth that would not have time to harden off before winter. Spray junipers early this month if you have crabapples or hawthorns nearby. Two sprays at ten day intervals will help prevent cedar rust.
No more pruning should be done on evergreens this season. Evergreens can still be planted at this time. Yellow leaves with green veins are a sign of nutritional deficiency in landscape ornamentals. Azaleas and oaks showing these signs are iron deficient; maples, manganese deficient. Plan to apply iron or manganese chelates to the soil or place implants in trees next spring. Treat severe infestations of lacebugs on sycamore, honey locust and other ornamentals with sevin, malathion, or orthene. Let aphid predators control large numbers of aphids in maple trees. The aphids cannot do any serious damage this late in the season, and spraying would wipe out aphid predators and other beneficial insects. Remove and destroy bagworms feeding on ornamentals. Spraying with insecticides will not be effective now. Tent-like nests of fall webworm can be seen on the terminal branches of trees. These late season defoliators can be controlled by pruning if desired. They cause only minor damage to trees. Vegetables You should now be in the heart of the harvest. Be extra diligent in harvesting cucumbers, bush beans, and summer squash when they are young and tender. Plant cool crops this month. Radish, spinach, lettuce, broccoli, cauliflower and Brussels sprouts. They will do better in the fall than in the spring. Maintain mulch on vegetable beds to keep the soil moist and to prevent blossom end rot on tomatoes, peppers and summer squash. Control blight and leafspot diseases in tomatoes by applying tomato sprays labeled for disease control. Avoid overhead watering and over crowding of plants. If wilt disease claimed your tomatoes this year, make a note to buy resistant varieties next year (labeled VFN resistant). For extra insurance, avoid planting tomatoes and closely related crops i.e. peppers, potatoes and eggplant, where any of these crops or strawberries grew this year. Blanch standard cauliflower varieties by wrapping the leaves around the heads when the heads reach 2 to 3 inches in diameter. Harvest when heads reach 6 inches across. Green, purple and self-blanching varieties of cauliflower don t need this treatment. Keep the garden well watered during dry weather and free of weeds, insects and disease. Complete fall garden planting by direct seeding carrots, beets, kohlrabi, kale and snap beans early this month. Lettuce, spinach, radishes and green onion can be planted later in August and early September. Don t forget to thin seedlings to appropriate spacing as needed. Harvest onions after the tops yellow and fall, then cure them in a warm, dry, well ventilated area. The necks should be free of moisture when fully cured in about one week s time. Harvest potatoes after the tops yellow and die. Potatoes also need to be cured before storage.
Pick beans, tomatoes, peppers and squash often to encourage further production. Harvest sweet corn when kernels are plump and ooze a milky juice when punctured with your fingernail. If the liquid is watery, you re too early; if the kernels are doughy, you re too late. Pick crops such as cucumber, summer squash and snap beans on a regular basis to maintain high production. As one-time crop, such as corn are harvested, remove plants and add to the compost pile to reduce insect and disease problems. Monitor beet and chard leaves for the white eggs of beet leafminer. Early in the month, plant fall crops of beets, endive, Chinese cabbage, kale, collards, kohlrabi and turnips. Control cabbage worms and loopers and tomato hornworms by hand picking and/or spraying with B.t., a bacterial disease of caterpillars. It does not affect other insects and leaves no toxic residues, so it can be used safely right up to harvest. If European corn borers or corn earworms are damaging sweet corn, treat developing ears with Sevin according to label directions. Harvest watermelon when several factors indicate ripeness. The underside ground spot turns from whitish to creamy yellow; the tendril closest to the melon turns brown and shrivels; the rind loses its gloss and appears dull; and the melon produces a dull thud rather than a ringing sound when thumped. Thin and/or transplant vegetables seeded in the garden last month. Would you like additional information? Additional information is available on-line. Please see MSU Extension- Oakland County s publications as well as MSU Extension s Bulletin Office on campus. Visit our Plant & Pest Hotline (248/858-0902) for assistance with plant identification, pests and diseases, weeds, trees and shrubs, lawn, flowers, fruits, vegetables, grasses and groundcovers, native plants, plant propagation, and many other gardening topics. Distributed by MSU Extension-Oakland County, 1200 N. Telegraph Road, Pontiac, MI 48341, 248/858-0880, www.msue.msu.edu/oakland, Updated August 2009 MSU is an affirmative-action equal opportunity employer. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status.