Q: My mother has two lilacs They are growing and doing well but only one of them flowers every year. Why is that?

A: In order to bloom, some lilacs need more winter chill hours than others. This is why transplanted lilacs that bloomed wonderfully in Chicago or Boston sometimes refuse to flower in Georgia. Southern gardeners report that ‘Angel White’, Dark Knight’, ‘Betsy Ross’ and ‘Miss Kim’ bloom reliably for them. Remember that lilacs prefer a soil pH that’s almost neutral. It’s not a bad idea to throw a handful of garden lime around each plant each year.