Is there a way to tell where a new bloom has set for next year? My bush did not bloom this year. We have a lot of new shoots which we want to cut back. Our question being on the older limbs how do we know how far to cut back? I'm afraid that last year blooms were cut off and don't want to do that again. So is there something to identify where new blooms are being set?
There may be a time and method to determine next season's lilac buds but I'm unaware of it. There are 27 species of lilac and many cultivars of those species, so there are numerous differences on bud formation and appearance. Rather than trying to find flower buds, focus on providing the best growing environment and cultural practices for your lilacs. Lilacs need at least 6 hours / day direct sunlight during the growing season. Soil should be well drained and not waterlogged. Lilacs do not require fertilization. Application of nitrogen fertilizer to or near lilacs may result in vegetative growth (lots of leaves) but few or no flowers, so don't apply fertilizer to or near lilacs. Many lilac species and varieties grow tall and if not pruned become leggy with many shoots. If that describes your lilac cut back as much as 1/3 of the top growth in any one season. Start by cutting out damaged branches and those rubbing, crossing or growing into the center of the plant. The plan is to eliminate all the old growth and to renew the shrub so it constantly is producing new primary branches that will grow for six or seven years and then pruned out entirely when it is seven or eight years old. An orderly, long term approach to pruning lilacs will result in shorter, more open, healthy shrub with flowers every year. Renewal pruning of trees and shrubs is a multi year project and learning experience. If a shrub is over-pruned one year it will respond by setting few flowers the next year. Ease back on the amount of pruning that season, never pruning more than 1/3 of the top growth in any season. Pioneer Fruit Growers in Alaska is a group of dedicated tree and shrub growers, mostly in south-central AK. They recently placed many of their newsletters on line. They may have articles on growing lilacs and general pruning guidelines in past issues. A Google search, or visit to the library should help you find useful information from the Pioneer Fruit Growers. Regards,