Q. How do slugs overwinter? I had a terrible slug problem this year and captured "thousands" in beer traps and by handpicking. I usually cover my garden with a layer of shredded leaves in late fall but now wonder if this mulch will actually protect them?
--Gerry Meyer, Sleepy Hollow
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A. Slugs overwinter as adults or eggs, concealed beneath the soil surface, under garden debris or light mulches. Applying a leaf mulch once the ground has frozen most likely is not going to increase your slug population. By that time, they have stowed away in the soil.
Eliminate their daytime hiding places by avoiding mulches in spring and summer and practice good garden sanitation by immediately removing dead plant material and weeds.
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Slugs lay clusters of 20 to 100 eggs several times a year. They feed at night and prefer succulent foliage (especially hostas), juicy young plant material and fruit.
Your methods of control are good ones, but judging from the number of slugs you catch, you might want to rotate in a few other methods: approved commercial baits; surround your larger plants with strips of screening or diatomaceous earth, a powdery deposit of silica and fossilized skeletons of marine and fresh water organisms; set daytime traps of rolled-up damp newspapers. Avoid watering your garden late in the day or at night.
Slugs will visit your garden as long as you have the plants they love. If you grow hostas, consider ones with corrugated, thick foliage instead of the thin-leaved varieties.
Q. On a recent trip to Seattle, I fell in love with the false cypress trees and shrubs planted everywhere. Is it possible to grow any of these evergreens in the Midwest?
--June C. Charleston, Naperville
A. Among the eight false cypress Chamaecyparis species and their numerous cultivars, are four hardy to Zone 5. False cypress trees grow in abundance in the Northwest because they prefer a cool, moist climate in deep, rich, well-drained soil, with protection from bitter cold and scorching sun. These conditions are not normal for our area. The species to consider for a Midwest garden are: Nootka false cypress (C. nootkatensis); Hinoki false cypress (C. obtusa); Sawara false cypress (C. pisifera); and Atlantic white cedar (C. thyoides). There is a large range of heights, needle color and habits within these four species. All can be seen at the Chicago Botanic Garden in Glencoe.
Q. A flowering catalpa tree is a gorgeous tree, but is it a good choice for Chicago gardens?
--M. M. Filipovich, Westmont
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A. The northern catalpa (C. speciosa), hardy in Zones 4 to 8, is native to southern Illinois, Tennessee and parts of Arkansas. It can grow taller than 70 feet. It prefers moist rich soil and is not a good choice for an urban street tree. The wood can be brittle and the large soft leaves are prone to tatter and caterpillar attack. The southern catalpa, C. bignonioides, while shorter than the northern, is hardy only to Zone 5 and could suffer during a very bitter winter.
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Lee Randhava writes for the Chicago Botanic Garden in Glencoe. Send your concerns to: Gardening Q&A, Home&Garden, Chicago Tribune, 435 N. Michigan Ave., Chicago, IL 60611-4041.
