Canna roots can be dug in late fall

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Q: I planted ten different cannas, which are all blooming, anywhere from three feet to six feet tall. I want to transplant the smaller ones. Do I have to wait for the blooms to finish? C. Yelb, email

A: The cannas will be happier if you wait until frost has killed the leaves. At that time you can cut the stems just above the soil surface and dig the thick roots from the ground. Cannas are usually, but not always, winter-hardy in the Atlanta area. You can store the roots wrapped in newspaper until planting time in spring. Or you could plant the roots where you like and mulch heavily.

Q: Is it too late to do a hard pruning on mahonias? Sylvia San Martin, email

A: I have mixed feelings about mahonia. The fragrant yellow flowers look great in late winter, and wildlife eagerly consume the blue berries that follow. However, I don't like controlling the wickedly spined shrubbery that sprouts in unwanted places in my woodland garden. If you don't mind missing the flowers, you can remove the tallest stems and shorten the longest branches now.

Q: I have pennywort in my St Augustine lawn. How can I control it? Ed Miller, Newnan

A: Like its weedy cousin, creeping Charlie, pennywort is tough to eradicate. Any of the three-way broadleaf weedkillers will give moderate control, but products that contain carfentrazone or quinclorac are better. Repeat sprays are necessary. Rather than give you brand names, I'm going to give you homework to read product ingredient labels. This will also inspire you to read and understand which lawn grasses these two chemicals can be used on. Remember too that pennywort loves damp soil. A dry summer will control the weed on its own.

Q: I want to mulch the beds in my yard and we really like black mulch because it makes the plants and flowers stand out. A neighbor said that black mulch is a bad idea because it absorbs heat from the sun and this harms plants. Mike Gorgone, email

A: I don't think you'll have a problem as long as the mulch layer is an appropriate depth, typically an inch or two. Any deeper than that and it might hold enough moisture and heat to sour and produce chemicals that would hurt your plants or yield unwanted mushrooms.

Q: Is it best to spray weed control on a fescue lawn before or after the lawn is cut? Phillip Witherington, email

A: Great question! You'll get best results spraying weed killer a couple of days after the lawn has been mowed, when the weeds are actively growing and recovering from damage. Spray, then wait a few days before mowing again, to give the chemical time to be thoroughly absorbed by weed leaves.

Q: While weeding, my wife discovered the hard way that we have a tussock moth caterpillar problem. What can I do to treat the issue before either of my kids comes up close and personal with these fuzzy little pests? Mike Knoll, Gwinnett County

A: The good news is that most venomous caterpillars are seen for only a few weeks in the fall. Also, in my experience, tussock moth caterpillars are much less venomous that saddleback caterpillars (Ow!). You can spray the suspected caterpillar gathering area with one of the organic caterpillar killers that contain Bacillus thuringiensis (B.t.). This organic product does not harm humans or animals.