With What and When to Fertilize Lilac Bushes

Question

What formula of fertilizer should I use and when should I fertilize my lilac bushes? My bushes are 3-4 years old and have not yet flowered. When should I prune them and when should I fertilize them?

Answer 1

First, you should know that your lilac are just now starting to reach maturity, usually lilacs don’t bloom for the first three or so years. So hang in there.

If your lilacs are lush and green, but have no buds or blossoms, it might be a sign that they are getting too much nitrogen – don’t use lawn fertilizers. Use a general purpose fertilizer high in phosphorus in the early spring. Lilacs like to have lots of sun, so if they’re in a shady area, they may not bloom well. Fertilize your lilacs once with the same type of formula again after pruning.

The best rule of thumb on pruning lilacs is to do it right after the flowers die off in the summer. Once your lilacs reach full height, six to eight feet, then you should trim some of the bushy growth. Start with the flowers, then some larger stems from the center of the bush, and the some of the small suckers and shoots at ground level. Be sure to leave a few healthy and strong branches to allow for new growth and some ventilation for next year. Use your best judgment on pruning, if you want tall bushes trim the sides more, if you want wide bushes then trim the tops a bit.