Answer: This is a named variety of Hydrangea macrophylla also sometimes called Pia. When to remove the old blooms is a matter of personal preference. If you like the look, wait and trim them away in the spring, otherwise they maybe removed as soon as they fade in late summer. In a colder climate the plant may receive a little bit of extra protection by leaving the old flowers intact until late spring.
This plant blooms on the old wood, meaning the growth made the previous year, so take care not to remove any extra branch or stem when you remove the old flowers. If you cut the shrub back in late summer, fall, winter, or spring you will be removing flowers for the coming season. Pruning can be kept to a minimum with this plant, just remove any winter killed branches each spring and, if needed, thin it lightly by removing some of the oldest branches at the base every few years.
Enjoy your hydrangeas!
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