When you cut the heads off hydrangeas depends on what you want from your plant. Snip faded flowers in summer if you want to push reblooming types into a second flush. Leave the dried heads on through winter if you want frost protection for the buds below. Both approaches work, but your timing changes the result.
I used to clip every brown flower head the moment it faded. Then one winter I got lazy and left all the dried blooms on my bigleaf hydrangea. Those papery clusters looked great covered in frost. They also shielded the tender buds sitting right below them from cold wind. That spring my plant made more blooms than any year I had clipped early. Now I leave the heads on through winter on purpose every single year.
A friend of mine with two Endless Summer plants ran her own test last year. She deadheaded one plant right away and left the other alone. The clipped plant pushed out a full second round of blooms in late August. The other one never rebloomed at all. Same bed, same water, same sun. The only difference was whether she cut those faded flowers off or not.
Deadheading hydrangeas works because of how your plants use energy. Once a flower fades, the plant starts making seeds inside that old bloom. Seed production takes a lot of resources. RHS notes that this drains energy your plant could use for roots and stems. When you snip off the old flower before seeds form, your plant puts all that energy back into growth. UMN Extension adds that dried flowers give your winter garden nice texture too.
To remove spent hydrangea flowers the right way, cut just above the first set of large healthy leaves on the stem. Use clean bypass shears and make your cut at a slight angle. This spot gives your plant a strong node to push new growth from. On reblooming types, that new growth often carries another flower cluster for you to enjoy in late summer.
For your once-blooming types like standard bigleaf or oakleaf, you won't trigger new flowers by deadheading. You still redirect energy, but there's no rush to clip. You can leave those faded blooms on through winter and remove them in late February before you see new buds swelling on the stems.
Here's your simple plan. Deadhead your reblooming types within a week of the flowers fading during summer. Leave your once-blooming types alone until late February. Then go through and snip off the dried heads before spring growth starts. Use sharp bypass shears and wipe them with rubbing alcohol between plants. The whole job takes less than ten minutes per bush and sets you up for a great bloom season.
Read the full article: How to Prune Hydrangeas by Type
