Image by Caitlyn Willows
By Heather Rhoades
Do you wonder about why my lilac bush never flowers? Having lilac bushes that won’t bloom is a common problem for gardeners. If you are wondering why is my lilac not blooming, keep reading to learn more about what you can do to make your lilac bloom.
Causes And Fixes For A Lilac Bush That Hasn’t Bloomed
There are a few reasons why a lilac may not be blooming. The most common reason for a lilac won’t bloom is a lack of sun. Often time, lilac bushes that won’t bloom are planted in a location where they get enough sun to live, but not enough sun to bloom. A lilac bush needs at least 5 hours of sun and preferably a full day of sun in order to bloom their very best. If you suspect that your lilac is not getting enough light, you will need to move your lilac to a sunnier location in your yard.
The next reason that makes a lilac bush never flower is improper pruning. Lilacs do not need to be pruned, but if you prune it back hard in order to rejuvenate the bush, the lilac bush will take several years to recover and may not bloom during that time. Even lighter pruning, simply to shape the bush, can affect how well a lilac blooms. Pruning lilacs in late summer will cut away the wood that would have been the blooming wood for next year.
A third cause of lilac bushes that won’t bloom is too much nitrogen. Because of this, you should not fertilize your lilacs. They do not need much in the way of nutrients and fertilizing can cause a lilac to take up too much nitrogen, which keeps the lilac bush from blooming. Also, lilac bushes planted near lawns may be taking up fertilizer used on the lawn. To correct too much nitrogen keeping a lilac from flowering, you can add phosphorus to the soil around the lilac.
Another reason that a lilac bush does not bloom is due to having a restricted root system. A restricted root system prevents the lilac bush from taking up enough phosphorus in order to bloom. Restricted root systems can be caused by over wet ground, container grown plants in a too small container and inadvertent root pruning. Typically, a lilac bush with a restricted root system will also grow poorly.
Yet another reason for a lilac not blooming, or not blooming well is that it is too old. Lilac bushes bloom best on younger wood and if your lilac is mostly old wood, the number of blooms will be reduced. You will need to do a rejuvenation pruning on the tree, which will affect the blooming further for 2-3 years, but after that the lilac bush will return to full blooming.
Pests or disease can also affect how well a lilac blooms. If you lilac is not flowering well, check the plant for these as well.