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How to Get My Lilac Bush to Bloom

I have two lilac bushes that are on the west side of my home. They are 5 years old, 5 feet tall, bushy and have never bloomed. I would like to cut them back to a smaller size. If they are not going to flower I want to pull them out.

I will appreciate your advice.

Bonnie T. – Salt Lake City, UT

Answer: The usual reason for lilac plants and other blooming shrubs to not bloom is being trimmed at the wrong time of the year. Lilacs should be pruned immediately after the blooming period. Since yours has not bloomed, you would just have to watch others in the area, then trim. Also, when you prune it’s good to thin an older shrub by removing no more than one-third of the older woody trunks, trimming down to within a few inches of the ground. Blooming is usually more vigorous on new growth. It would also be advisable to give the shrub some fertilizer in the late winter/very early spring, usually just around the time of your last snowfall. I would recommend using Hi-Yield Triple Superphosphate as the phosphate is what the plant needs the most for blooming. Avoid giving it too much nitrogen, which is the first of the three numbers that will be listed on the product. The nitrogen will just produce lots of green leaves and no blooms.

Also check your plant’s location and the amount of sun the plant receives. It should be getting four to six hours of sunlight daily. Lilacs transplant easily, so try taking one of the divisions or side shoots and plant it in a different location. Southern exposure is always good. See if your luck improves.

Some lilacs do take several years to reach maturity and a blooming state. You might try not pruning it this year. Give it some Superphosphate in the spring and see what happens next year.

Good luck and happy gardening,

Karen

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