|I have two lilacs, one in a mostly sunny spot, the other in a half shady spot. Neither will bloom with more than 2 or 3 stems. What can be done? Thanks!|
|I apologize for the delay in responding. We were flooded with questions and are working to catch up!
Lilacs not blooming is a very common problem and a frequently asked question. First, very few lilacs will bloom before their 3rd season. The most common reason that older lilacs don't bloom is a lack of sunlight; they need full sun to only partial shade (at least 6 hours of full sun) to flower well. Without sun, the plant puts on plenty of foliage but no blossoms. Are you "feeding" your lilac? Add an inch or so layer of organic matter such as compost around the shrub out to its dripline each year. You can also try a a phosphorus source such as bone meal, or a fertilizer with the middle number high (5-10-5) in phosophorus, which promotes bloom. Make sure it isn't "sneaking" nitrogen from another source, such as lawn fertilizer, which will promote foliage at the expense of bloom.
There is also an outside chance that your type of lilac isn't the right type for your area.
If you are really desperate, try root pruning the shrub. Next late summer, dig
one shovel's depth deep around the drip line of the plant. This will sever
some roots and maybe shock the plant into setting flower buds.