fall shrub pruning
I have been reading that it's best NOT to prune shrubs in fall, however I did not prune the lilac seed pods, hydrangea flowers, and some other flowering perennials yet this year. Should I do this now or wait until spring before they bloom?
The reason that shrub pruning in the fall is generally not recommended is because it encourages plants to put out new, soft growth just as winter is coming, leaving it likely to be damaged..
The pruning/clean up you are mostly talking about is a little different.
For instance, cutting off just the spent, dried flowers of hydrangea or lilac is fine. Do not however cut the woody stems, which is where the flower buds for next season have formed this year. (They may not look like buds yet, but they are there.)
How to best care for perennial flowers depends a bit on which ones you have. Generally though, many can be left for spring, and it is beneficial for many insects and wildlife such as birds for food and winter shelter. Also, some seed heads are lovely when covered with frost or ice.
If you have specific perennials you are wondering about, let us know.