Blossom Bust

My 20-year-old lilac bush won't bloom. The foliage looks great, but how can I get it to flower? —Eugene Bankey, West Chester, Pennsylvania

Melinda: Let's start by evaluating the lilac's growing conditions and care. A common cause of poor flowering is improper pruning. Lilacs set their flower buds the previous season. Pruning lilacs any time other than right after flowering eliminates next season's bloom. So adjust your pruning schedule if needed.

Now look at fertilization. Too much nitrogen fertilizer can result in lots of foliage and no flowers. Switch to a low-nitrogen, slow-release fertilizer, and use it only if your plants need a nutrient boost. Better yet, get a soil test and find out what type of, or even if, fertilizer is needed.

Another blossom-buster is excess shade. Lilacs flower best and have fewer disease problems when grown in full sun. They will tolerate some shade, but will fail to bloom if pushed past their limit. If shade is the problem, consider planting a new lilac in a sunny spot in your yard.