Why lilac tree wont bloom

The new buds form shortly after the flowers die back. Prune in spring immediately after the blooms have faded. Cut just below the faded bloom. The bush is immature. Most varieties need a few years to grow and develop, before they produce their first blooms. A pH imbalance or too much or too little of certain chemicals. You might want to have your soil tested. Sometimes, people use high nitrogen fertilizers, especially for their lawns, which will help produce green leaves, while hindering blooming.

Too shady a site. As lilacs mature, they can grow leggy and overgrown, with little foliage toward the bottom of the shrub. When this happens it may be necessary for a complete rejuvenation by pruning them to within 12 inches of the ground. This should be done in late winter when the shrubs are dormant. To prevent the interruption in bloom cycles, lilacs can be given a rejuvenation pruning over a two-year period.

What is the reason, exactly, why these classic plants fail to bloom? Well, rather than zeroing in on a single explanation, look at several possible reasons behind this problem, which include in addition to diseases and pests :. Notice that, while numbers one and three speak to the gardener's having done something wrong, reasons number two and four are nobody's fault.

Why does the precise time that you prune matter? Lilacs are shrubs that bloom on old wood. This means that the flower buds for the next spring's blooming period are set on the growth produced during the prior year. When you prune off this growth, you lose the flower buds—and, by extension, the flowers that they would have brought.

That is why you are advised to prune lilac bushes right after they are done flowering before they have set bud for next year. The common lilac Syringa vulgaris is a very cold-hardy plant, but if a hard frost or a freeze comes along just as the flower buds are about to open, they can be damaged. This results in the loss of blooms for that year.

There is not much that you can do to prevent this; just accept the loss and appreciate next year's blossoms twice as much. As with most plants, where you have planted your lilac bush very much matters. Lilacs are full-sun plants that want well-drained soil. If you made a mistake on either of these fronts when you first installed your plants, you may be paying for it now—in the form of your lilac not flowering. But there is an easy remedy to the problem: transplant your shrub to a more suitable spot.

Regarding reason number four, be aware that, while these bushes are long-lived, their flower production does tend to peter out over the decades. The solution to this problem is to perform a rejuvenation pruning on your lilacs do not expect immediate results, though.