Answer: The most common reasons for a lilac not to bloom are immaturity, too much shade, pruning at the wrong time of the year and excessive nitrogen fertilizer. Since your plants are only two or three years old, I suspect that is the problem and as they mature, you'll begin to see them develop flower buds. Lilacs bloom on wood grown the previous year, so any pruning must be done in the spring immediately after the shrub blooms. Pruning in summer or fall or early spring will remove flower buds. At this point, I would just be patient, and withhold fertilizer. Watch your plants next spring and summer. I think you will be able to detect flower bud formation at the tips of the new growth. Hope so!
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