Q: My hibiscus shrubs bloom from mid-summer through fall. The buds and leaves have all turned black, and they have white insects all over them. Susan Boling, email
A: Hibiscus whitefly is a common pest of outdoor hibiscus plants. The small white flies gather on the back of leaves and suck sap. The sap that cannot be digested is excreted and falls on nearby buds and leaves. A sooty black mold grows on the sap (honeydew), causing the whole plant to be unattractive. The first way to control whiteflies is to spray the plant with a strong stream of water every three days. This will wash away many whiteflies and their eggs and will also get rid of the sooty mold. A systemic insecticide can be used as a last resort but I don't like doing this because of the danger to pollinating insects.
Q: I just bought a house with overgrown azaleas. They are full on top but not dense underneath. How and when do I prune? Kipp L., email
A: Sometime in February or early March would be the absolute best. Of course, pruning at that time means you won't get any flowers that season but you'll get very strong regrowth of greenery on the lower part of the plant. This can be shaped into a nice looking, but smaller, azalea. If you prune now in the heat of summer, you won't get much regrowth and you won't get flowers either.
Q: We recently had a new home built. Sod was planted the last of June. For the first two weeks, the sprinklers ran each day at sunrise for 40 minutes per zone. I run them for 20 minutes per zone after each mowing. Now my entire lawn has turned brown and is nearly dead. Paul Asby, email
A: This sounds to me like the sod was watered too much. It is good practice to water heavily for a few days after laying sod but your eventual goal is to reduce irrigation to an inch of water applied once a week. You do this by applying slightly more water but at longer intervals between each irrigation. Current weather and temperatures determine how long it takes to get to the goal of one inch per week. Grass grows best when it is watered deeply and allowed to dry somewhat before water is applied again. I've outlined one example of a sod watering schedule at bit.ly/GAsodwater but it could be greatly different depending on weather.
Q: I have a new house with a young maple tree in front. I don't want to stunt my small front lawn from growing. What's the best tree that allows sunlight to come through? Ruby McCullough, email
A: To have a nice lawn plus a tree, you need a tree with upright or oval branching habit, rather than the spreading branches of a maple. Consider kousa dogwood, crapemyrtle, hornbeam, and zelkova to replace the maple.
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