Yellow clematis leaves a sign of overwatering

Q. Why are my clematis leaves yellowing?A. Yellow leaves are usually a symptom of overwatering or a mineral deficiency. Clematis need regular watering, but it is important not to let them become waterlogged. Always water thoroughly and deeply during the hot summer months. Don't keep them too wet, especially in the winter when they're dormant.Clematis is a heavy feeder. When growth first starts to appear in spring, fertilize with a low-number fertilizer, such as 5-10-10 or a rose food. Choosing a fertilizer with a low nitrogen number relative to the phosphorus number, such as 5-10-10, helps the plant develop blossoms and roots, rather than lots of foliage. You can also top dress the soil with 2 inches of rotted manure. Feed again after flowering has finished.#160;When mulching the garden always keep the mulch 6 to 8 inches away from the plants stem to discourage fungus problems.Q. I have a maple tree that has a gray-green growth on the bark. What is it?A. Chances are the gray-green growth is lichen. A lichen may look like a single organism, but it is actually consists of a fungus and a green or blue-green alga growing together in a mutually beneficial relationship. Lichens can be flat, leafy, or branched and hairlike. All three forms occur on tree bark as well as on rocks, and soil. Colors may range from white to gray, red, green, yellow, and black.Although lichens grow on tree bark, they are not parasitic (disease-causing organisms), and do not harm trees. That's because it takes its nourishment from the air rather than from its host. Since most lichens will not grow in a polluted atmosphere, the air nearby is relatively pure. Lichens are often blamed for the decline and death of trees because they are commonly found on dead branches. The truth is that exposed limbs on damaged plants simply give lichens access to the sun they need for growth with little competition. Lichen grows well in winter after the leaves have fallen from deciduous trees and no longer block the light. Lichen also grows actively during wet, humid conditions. bull; Provided by Mary Boldan and Donna Siemro, University of Illinois Extension Master Gardeners. Send questions to Ask a Master Gardener, c/o Friendship Park Conservatory, 395 W. Algonquin Road, Des Plaines, IL 60016, (847) 298-3502 or via e-mail to cookcountymg@sbcglobal.net.