Q: I want to replace four 'Bradford' pears with native serviceberry trees. Is there a certain variety I should look for? — Patty Griffeth, Bethlehem
A: There are several species and hybrids of serviceberry that grow very well here. I love the plant's springtime white flowers, edible fruit and bright fall color. 'Autumn Brilliance' is usually stocked by local nurseries, but other varieties may be just as good.
Q: Is it safe to use hay, as mulch and in a compost pile, that has been treated using 2,4-D? — Kerry Brookshire, email
A: I don't think I can say that it's "safe" in all situations. The weed killer 2,4-D has a half-life of seven to 60 days, depending on whether it's applied to water or soil. Soil microbes do much of the work to break down the chemical. However, several plants, tomatoes in particular, are extremely sensitive to very small amounts of this herbicide in mulch. I think it's too risky to use herbicide-treated hay in a vegetable garden or in flower beds. There might be places in a landscape where the hay could be used, but I think you'd be better off not to use it at all.
Q: We will be planting four or five water oak trees in a straight line in an old pasture. How far apart should we plant them so they grow to their full potential? — Judy Morris, Gwinnett County
A: The rule of thumb for spacing trees is to plant them at least as far apart as their normal branch spread. A single water oak, Quercus nigra, will eventually have a branch spread 50 to 70 feet wide. I'd go with the lower number and plant your trees 50 feet apart. Don't forget to mulch widely underneath the branches. Mulched trees have twice the growth rate compared to those unmulched.
Q: In shady areas is it OK to plant a blend of fescue and other grasses? — Dennis Nast, DeKalb County
A: You can certainly plant a "shade loving" fescue blend. Most of the shade mixes have a combination of bluegrass, rye grass, red fescue and tall fescue. The grassy area will look fine in winter when leaves are off nearby trees. But, as the shade deepens and heat arrives in summer, all of these grasses, including the fescue, will gradually thin and die out. One trick to try is mowing the grass as high as your mower can be set. The increased leaf length allows the grass to scavenge as much light as possible.
Q: I have been told that you have a formula of Miller beer, Tide detergent and something else to get rid of crabgrass. What was the last ingredient? — Dorsey Hunt, Gwinnett County
A: This supposed lawn tonic recipe and its variants have been passed around since the '60s. Beer, detergent, ammonia, aspirin, tobacco and other household items are prominent in the recipes. No matter what hucksters say, science shows that the recipes do not work. Do not waste your time. I give more details at bit.ly/lawnmyths.
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