Hello Stephen,

Lilacs generally do not need fertilizer—especially since the chemical phosphorus is the nutrient that promotes blooming and most soils in Michigan have a high percentage of phosphorus. To establish whether you need to fertilize, you should obtain a soil test. To obtain a kit, go to https://homesoiltest.msu.edu/get-started. The analysis will describe what fertilizer to use and how much to apply. Fertilizing is generally done in the spring.

Lilacs do not require a lot of maintenance, but if you do decide to pruning, it should be done immediately after blooming. If you wait until later, you will prune off next year’s buds.

You did not specify which lilac you have. Attached are bulletins about the three species that are the most commonly available.

https://www.mortonarb.org/trees-plants/tree-plant-descriptions/common-lilac

https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=a286

https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=c152

I hope this information helps you with your lilac.

Cicada Brood X Will probably be concentrated in states south of Michigan but may appear as far north as Ann Arbor but not much more.

Cicadas generally are not harmful to the ecosystem. Although they may cause some damage to smaller tree branches which they use as receptacles for their eggs. Possibly covering your small lilac with mosquito netting when the cicadas emerge and for about six weeks after that may protect the small lilac. Here are two articles that explain Brood X Cicadas.

https://www.mlive.com/life/2021/01/billions-of-17-year-cicadas-are-about-to-emerge-and-swarm-michigan.html

https://www.canr.msu.edu/news/what-s-all-the-excitement-about-cicadas

I hope this answers your questions.

Thank you for contacting Ask Extension