Snowball viburnum sports bright white blooms on a large shrub. CONTRIBUTED BY WALTER REEVES

Prune snowball bush now

Q: When is the best time of year to trim a snowball bush? My bush is 10 feet tall and I want it shorter. Janet Nipper, Gwinnett County

A: The best time to prune a snowball bush, Viburnum macrocephalum, is after it finishes blooming and the white flowers have turned brown. Keep in mind that this shrub is naturally quite large. To keep it small, you’ll have to prune it every year after flowering.

Q: I am trying to create a shade garden under several large white oaks where the soil is dense clay. How can I amend it? I have seen something called an air spade that injects compressed air to break up the dirt. John Mays, Jackson County

A: The air spade is a useful tool, but there are several things to consider when using it under a tree. Digging radial trenches and putting amended soil into them is one approach. It may help the tree grow better roots, but it doesn’t amend the overall soil surface for the perennial plants you want to install. You can’t use the tool to blow all of the soil off the tree’s roots because many of the fine feeder roots will be damaged in the process. The tree won’t be able to absorb moisture in summer. Since white oaks don’t easily tolerate drought, you could end up killing the trees if you do the air spading now. You could remove and replace the soil in quadrants around the tree, but I still think this would be better done in fall. You need to get advice from an ISA-certified arborist who has lots of experience using an air spade.

Q: When is the best time to overseed my lawn with TifTuf Bermuda? Greg Denard, Washington

A: You can’t overseed with TifTuf because it is a hybrid plant. It does not produce seeds. TifTuf Bermuda grass was hybridized by University of Georgia researchers. It looks better and is faster growing than older varieties and uses 30% less water. It is propagated by planting small sprigs, letting them spread and knit together, and then harvesting the grass as sod pieces or rolls.

Q: Can you recommend a good bat house? How best to install? Is it a good method of mosquito control? Lyn Priegel, Cherokee County

A: From my observation, successful bat houses are a minimum of 24 inches high and wide. The best ones are the “nursery“ type houses that have several narrow chambers inside. Much of your success attracting bats depends on where the bat house is located. They are most successful when installed near open water or at the edge of a woodland. I do not recommend putting bat houses in spots frequented by kids or pets. Although putting up a bat house is a good ecological deed, bats are not very good at mosquito control. Bats prefer night-flying moths and beetles: They are simply “meatier“ than a tiny mosquito. You can get excellent tips on building and installing bat houses from Bat Conservation International, batcon.org.

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.

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