There are several possible reasons for a lilac bush not blooming.  Most importantly, lilacs need to be grown in full sun to flower well. They need at least 6 plus hours a day of direct sun.

If your lilac is growing in a sunny location, consider the following:

• The plant may be getting too much fertilizer, either from plant food that you are applying or from a nearby lawn.  Cut down on the amount of fertilizer that the plant gets and use a formula that is low in nitrogen (the first number listed on the container) and higher in phosphorus (the second number).
• Make sure that the plant is well watered during any dry spell in summer.
• Do not prune in late summer. If the shrub needs to be pruned, do so immediately after flowering.
• Check the pH of the soil. Lilacs prefer a neutral or even slightly alkaline soil. If necessary, add lime to the soil.
• If you recently planted your shrub, it may need time to get established, or it may simply be too young to flower.
• Also, an easy fix is to add compost (couple inches) to the soil to condition it producing great growing conditions.

For tips on a variety of gardening topics, see our Plant Information Guides.
- Courtesy of NYBG Plant Information Service