Good Morning-

How fun to have those beautiful bonus blooms in the fall!

Your plants are blooming again because of stressful growing conditions this summer—lack of rain, extreme heat, heavy pest damage, or possibly over pruning. The answer to your question is that they will bloom again in the spring, but maybe to a lesser extent. Lilacs, forsythia, rhododendron set their flower buds for the next year in the early summer, shortly after the spring blooms fade. Stressful conditions in the summer followed by cool temperatures trick the plants into blooming again. In the future, watch for droughty weather and water your plants, avoid heavy pruning, or monitor and manage the pest population.

I have attached a couple of articles for you to read that will explain the additional blooming.

Enjoy the blooms!

https://yardandgarden.extension.iastate.edu/faq/why-my-lilac-blooming-fall-instead-spring

https://extension.umn.edu/yard-and-garden-news/reblooming-plants