Q: I know that potted mandevilla cannot live outdoors below 50 degrees. But what if the root is buried in the ground — will it come back in the spring? Dave Reeves, email
A: Mandevilla roots are almost as sensitive to cold as the stems. I’ve tried three times to get one through the winter outdoors, and after three strikes, I’m out. On the other hand, if you have room indoors, you can bring the pot inside and situate it before a bright sunny window. You may need to trim it to fit the space. Lots of leaves will drop during winter, but the plant will usually come back strongly when you plant it outdoors in spring.
Q: I have purchased a bay leaf plant and would like to plant it in the ground. What kind of sun exposure would work? Dinny Gujral, Cumming
A: Bay laurel, Laurus nobilis, is the source of aromatic leaves used in cooking. It tolerates full sun to light shade. But keep this in mind: It could be hurt by cold. The shrubby tree is reasonably cold-hardy, but if temperatures are forecast to be below 15 degrees, cover it with black plastic down to the ground on all sides and put a 60-watt bulb in there to keep it from freezing. Prune it occasionally to keep it compact.
Q: I transplanted two maple trees from my lot at Bent Tree. They were small and exhibited beautiful red leaves. But here after several years, they only turn a pretty yellow ... no scarlet. Why would that be? Gary Johnstone, DeKalb County
A: As you know, tree leaves change color as light levels and temperatures drop in the fall. Green chlorophyll disappears and the pigments that produce yellow, orange and red, which were there all along, become visible. Fall leaf color on a tree is determined by the interplay of light, temperature, stress, and the pH of the leaf sap. In Bent Tree, the trees were probably unstressed and were growing in an environment that favored production of anthocyanin in fall so the leaves turned red.
But now they are growing in a different temperature and light environment, and that is likely the reason they are yellow. There are maple tree varieties that have been selected to be more consistent in their fall color in varied conditions. ‘Autumn Blaze’ and ‘October Glory’ are examples.
Listen to Walter Reeves’ segments at 6:35 a.m. on “Green and Growing with Ashley Frasca” Saturday mornings on 95.5 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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