I have two everblooming lilacs which were progessionally planted last year in a large planter on my terrace. This spring they had lots of blooms and were lovely. They now however look bedraggled and did not bloom again. Their leaves have white borders , white spots and a whitish film. Some of the leaves are also drying up. They are watered frequently but they do get a lot of wind since I am near the lake. Suggestions?
I expect the plants you have are the Bloomerang lilacs, which are repeat bloomers. According to the vendor, Proven Winners, “The rebloom of Bloomerang lilac occurs on the new growth the plant creates after its spring bloom. For the best rebloom, it’s vital that the plant grows vigorously during late spring and early summer. Do this by keeping it well-watered and mulched and in plenty of sun (six hours a day at least). If you wish to fertilize it, you may do so in early spring, once the ground has thawed, and again in late spring, after it blooms.
It does not need pruning, but giving it a light trim after blooming does remove the developing seed heads (they look like green bananas, and some people don’t care for the way they look on the plant), providing a neater look, and encourages more new growth for reblooming. Trimming after blooming will delay the rebloom by a few weeks compared to an untrimmed Bloomerang lilac.
Plant only in full sun and well-drained soil; lilacs cannot tolerate soggy, wet conditions.”
Given this and the initial information you provided, there are several concerns:
- If, by “on the terrace”, you are describing an area that doesn’t get a full 6 hours of sun, that would hinder reblooming.
- If the plants were pruned, their blooms may have been delayed.
- If the plants were overwatered (which is possible in a planter), they could be suffering as a result. Check that the soil is not soggy and that the roots are not rotting.
- The white on the leaves you describe is almost surely powdery mildew, a common fungal disease that occurs on lilacs. Powdery white spots usually appear first on the lower leaves and quickly move their way upward on the plant until the majority of leaves are covered in white or gray fungal growth by late summer or early fall. Luckily, it is unlikely to kill the plants. To prevent its return next year, make sure to very thoroughly clean up any fallen leaves or plant debris.
I hope this helps you to manage your lilacs.