Answer: Lilacs may bloom less if they are in need of more sunlight, if they have been pruned at the wrong time of year, or if they have not been pruned regularly over the years. Routine pruning would be to remove the faded flowers and to remove any suckers smaller than a pencil each spring. After bloom, also remove some of the oldest stems by cutting them at the base, at the ground. This causes the plant to constantly renew itself with new growth coming up from the roots and stay vigorous. It also helps it stay shorter and bushier. Some lilacs bloom heavier one year and lighter the next on an alternating schedule. You may find that yours is one of these. Six hours of full sun is minimum for lilacs. They grow and flower best in 8 or more hours of direct sunshine. Best wishes with your lilacs.
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