Am I too late to cut dried white hydrangea stem tops now, or should I leave untouched.
Please advice, thank you.
This is a timely question. Late winter or early spring is the right time of year to prune your hydrangea, including its large dried flower heads, which by your description is most likely to be the popular and reliable Annabelle Hydrangea (H. arborescens ‘Annabelle’ ). You can identify your hydrangea here: https://plantaddicts.com/types-of-hydrangeas
‘Annabelle’ hydrangeas bloom on new wood, which means that flower buds are set in the same year that they bloom (unlike some other varieties which set their buds the previous fall and thus should not be pruned until after they flower).
Most experts recommend pruning back to the first set of leaf buds, which would be at 3-4 inches up from the ground. Alternatively, if you prefer not to cut back so drastically, you could prune all the stems back to about the 8-10 inch level, cutting right above a set of leaf buds. In this way you will remove the flower heads and will provide a slightly longer stem that will give your shrub additional support for this year’s heavy blooms. Any dead branches should also be removed by cutting them off at the ground.
Here is an informative Toronto-based article that will help you to identify the right place to make your pruning cuts: https://www.torontogardens.com/2009/04/pruning-annabelle-hydrangea.html/