Q: In late July my star magnolia, planted last fall, suddenly almost completely defoliated. I kept it watered through the winter and only occasionally this summer since rain was frequent. It looked healthy in early July. Any idea what the cause is? John Champion, Fulton County
A: It sure sounds like a water or root issue to me. I know you watered this summer but my bet is that the roots have not lengthened very much from the initial planting. Slow root expansion is particularly common when roots in the original root ball are not untangled before planting. I know the planting tag for many trees and shrubs indicates that digging a hole a couple of times wider than the root ball is sufficient. But new research shows that removing most of the potting soil and untangling the roots to spread them in all directions in their new soil home is the best planting method. Grasp the trunk of your tree and try to wiggle it back-and-forth. If the root ball moves very much, the roots have not grown outward as much as needed to survive a short dry spell.
Q: How do I control lespedeza? Tammy Smith, email
A: I see two kinds of lespedeza that are problematic in lawns. Annual lespedeza, Lespedeza striata , is a low-growing annual plant; it sprouts from seed each year. Sericea lespedeza, Lespedeza cuneata, is an upright perennial plant. Both have tufts of three leaves arranged along the stem. Common lespedeza thrives in thinly growing lawn grass and on compacted soil. Your best option for control of either plant is hand pulling as soon as you spot it in early summer. Waiting until fall allows both plants to develop woody stems and deep, tenacious roots.
Q: Can you give me ways to decrease water holding in my back lawn? Water comes from a small hill on the side of my house. Might a rain garden help soak up some of the water? Tabatha Burks, Fulton County
A: If your lawn has a wet area, grass won’t tolerate it. One option is to slightly excavate the area, to concentrate the water, then install plants that tolerate wet feet. I have lots of details on rain gardens, including a list of plants for damp soil and a rain garden manual at bit.ly/GAraingarden.
Q: On your website you write that butterfly bush is a good plant to attract butterflies. While that is true, the Georgia Department of Agriculture says butterfly bush is showing signs of becoming invasive. Eric Bowles, email
A: I know that other states have declared butterfly bush, Buddleia davidii, to be invasive but the Georgia Exotic Pest Plant Council (www.gaeppc.org/list) does not list it as being problematic at this time. I’ll take their word for it but I note that several new butterfly bush hybrids are described as sterile. You could plant them instead.
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Listen to Walter Reeves Saturday mornings on News 95.5 FM and AM750 WSB. Visit his website, www.walterreeves.com, follow him on Twitter @walterreeves, on Pinterest, or join his Facebook Fan Page at bit.ly/georgiagardener for more garden tips.