Nearly spring and new buds appearing should I cut the dead heads now as it’s still a frost at night?
Dead Heading Hydrangeas
Pruning technique for hydrangea depends on the type you have. See the article, below. For spring pruning, I would trim when leaves are just starting to emerge. https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/prune-hydrangea-bushes-hydrangea-pruning-instructions.htm