Gazette Gardener: Proper pruning, circulation can help lilacs bloom, thrive

Lilacs too big? Or, too scraggly? If you want your lilacs to be at their best next season, now is the time to prune.

Between now and the end of June is the best time of year to tend to lilac bushes. So I thought it would be good to address some commonly asked questions.

Q: My lilac hasn’t bloomed since the first year it was planted. Any ideas on why? It grows a lot of green leaves and looks healthy.

A: This is a common question. First, consider the location. Lilacs need full sun and well-drained soil.

Another possibility is improper pruning. Lilacs should be pruned immediately after flowering up until late June. This is because the next season’s flower buds develop on new growth that occurs in summer. Pruning at any other time will remove these buds and therefore any possibility for flowers the following year.

The last possible cause is too much nitrogen. This is often the case when a lilac bush is growing adjacent to lawn that gets fertilized.

Q: My lilacs have grown spindly with flowers that are too high to enjoy. When and how should I prune?

A: Reach into the base of the lilacs and, as close to the ground as possible, cut back about one-third of all the oldest canes. Next spring, do the same thing and take out another third. And the year after, repeat the process. What will happen is new branches will form and you will have lilacs blooming at a level where you can see, smell and enjoy them.

Q: Every August, the leaves of my lilac get a white substance on them. What is this?

A: This is powdery mildew, a topical fungus. It generally shows up when it is hot and humid.

The best solution is to improve air circulation around the bushes. This can be done by thinning surrounding plants and also by pruning the lilac’s interior branches. To prevent spreading powdery mildew to other susceptible plants — such as phlox — be certain to clean up the infected leaves. And, don’t put those leaves in a compost pile. Instead, place them in the trash.

If you want, you can spray with a fungicide, but this is effective only if done before the mildew appears. Don’t bother to spray once the mildew is present. It is too late.

Also, it is likely that the spray will need to be repeated throughout the summer. Follow the label instructions.

Q: At the base of my lilac are suckers. Can these be removed and replanted?

A: Absolutely. Dig the suckers out and transplant them to a sunny location. In the hole, mix compost with the soil. Try to do your transplanting on an overcast day, keep the roots out of the sun and water the plant well that day and until you see new growth. Fertilize next spring.

Q: I have a lilac with barely any fragrance. Is this normal?

A: Not all lilacs are the same. In some cases the fragrance takes a back seat to the unusual colors we see in many hybrids. In my opinion, the best scents come from the common lilacs.

To be sure you get a fragrance you love, next May visit a lilac nursery like Bates Hops House in Cherry Valley and sniff until you find a lilac fragrance you enjoy. That way you won’t be disappointed again.

Q: Are there such things as miniature lilacs? I’m seeing a small shrub with lilac-like flowers blooming in Clifton Park. The flower fragrance is very pleasant. Can you tell me what these are?

A: There are several smaller lilacs. The “Palibin” and “Josee” cultivars grow 4 feet tall and 5 feet wide, “Tinkerbell” grows a little bigger (5 by 5 feet) and “Miss Kim,” a semi-dwarf that will grow 6 feet tall and 6 feet wide.

Q: Can you plant the seeds that form on a lilac bush? How do you go about it?

A: Lilac seeds need to be placed in a cold, moist environment for three months. This process — called stratification — simulates winter conditions.

In the home, the best place to accomplish this is in the refrigerator crisper.Once the stratification period is complete, you can plant the seeds in a sunny location where you want them to grow.

Happy gardening.