Hello! Spring blooming shrubs should be pruned directly after they bloom Here is a factsheet specific to lilacs https://extension.umn.edu/trees-and-shrubs/lilacs#pruning-1923160. For hydrangeas, it depends on what type of hydrangea it is. Here is an extensive overview of all different types of hydrangeas, including pruning information at the bottom of the chart. https://bpb-us-w2.wpmucdn.com/u.osu.edu/dist/d/1472/files/2015/05/Hydrangea-Chart-2023.pdf. https://u.osu.edu/barrett.90/2015/05/22/hydrangeas-for-ohio/

For burning bushes, prune your in late winter/early spring. This is the best time to shape and trim the shrub to the height you'd like it to be. We don't suggest taking off more than 1/3 of living material at one pruning.