How to keep the flower garden looking great
Continue to groom your perennials and annuals by removing yellowing foliage and spent flowers. Make note of perennials that have flopped and need staking so that a support system can be installed next spring before the plants actually need it.
Gentle pruning back of more vigorous perennials can help keep your border from looking overgrown. Cutting leaves off at the base can reduce the size of the plants without having them look pruned.
You may want to let certain dried flowers on plants such as astilbe and coneflower to remain standing for fall and winter interest. Gold finches visit my coneflowers in fall and eat the seeds.
• The gladiolus produces a large, showy flower spike that lasts for several days whether in the garden or in a vase. To get the most out of a bloom for decoration inside, cut when the lowest blossoms have begun to show color.
Place the cut stem in water as quickly as you can. The uppermost blooms will soon flower.
Stagger the planting of gladioli early in the season to provide flowers over a longer period of time.
• This is the time of year to check closely for magnolia scale, an insect about the size of a pencil eraser.
Typically found on the underside of magnolia branches, the scale is responsible for creating an overall thin condition on the tree. The scale exudes a clear, sticky honeydew after feeding on the plant. Black, sooty mold is a fungus that grows on the honeydew.
Gardeners often notice the black mold on or under the magnolia before noticing the actual scale. The presence of this black mold on other types of trees can also indicate problems with other insects. The mold itself is not the real problem.
On small trees, simply pick off the scale and squash them. Other control measures include spraying with summer-weight oil, or applying an insecticide when the scale is in the active crawler stage, generally in early September.
For trees with a history of magnolia scale, a late winter to early spring application of dormant oil will provide good control for the scale. If your tree is affected, provide extra water during summer to minimize stress.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.