Experts and BHG readers answer.
How to grow beautiful Miss Kim Lilacs
Hi, Miss Kim will bloom once a year. You can clip the old flowers off the plant to make it look nicer, but otherwise, as long as it gets plenty of sunlight, they should do fine. And yes, there is a reblooming Korean lilac called Bloomerang that we sell at BHG if you are interested.
Miss Kim will not rebloom to any great extent. Three weeks seems about right. There is a reblooming lilac on the market that gives you some repeat bloom through the season, if you are interested (I think you can get it through White Flower Farm).