Answer: There are several reasons your lilacs may not be blooming. First off, transplanting and planting are stressful and it can take several years for the plant to recover and build up the strength to bloom again. Next and definitely a problem, is when you pruned them. These shrubs bloom on old wood that grew the year before, and the growth needs enough time during the growing season to set buds. A summer pruning will remove flowering wood for the following spring and prevent or greatly reduce blooming the next year. So the only time to prune these is right after they bloom in the spring. Next, these shrubs need full sun to bloom well. They also need only average fertility, so make sure you are not overfertilizing them with nitrogen. An annual top dressing of compost and/or a spring time application of general purpose granular fertilizer such as 10-10-10 per the label directions should be enough. I hope this helps you trouble shoot.
Q&A Library Searching Tips