ok to trim in the fall butterfly bush,hydranga,weeping cherry tree,spyarea
best time to trim fall or spring
Certified GKH Gardening Expert
Each plant will have its own preferred time for pruning based on species, and cultivar. I will include some articles that will help with each of those in your question.
In Michigan winters, butterfly bush dies back almost to the ground. If leaves have dropped, it's OK to prune it down to 9 inches. Don't prune any of your plants if leaves haven't dropped. They are busy getting themselves ready for winter and dormancy. This takes about a month. Pruning during that month sends the opposite signal to the plant: grow, baby grow! Fragile new growth is then killed by winter. Spirea can be pruned anytime except spring and reducing them, even thinning out some interior branches once the leaves drop, will lessen the risk of heavy snow causing damage.