Should I fertilize both my flowering shrubs and non-flowering shrubs at the same time this fall?
Certified GKH Gardening Expert
I always recommend fertilizing in spring, as most of that will have been wasted by springtime. Bushes will tend to grow much less in winter.
Here is an article for more information: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/best-times-to-apply-fertilizer.htm