Answer: Your hydrangea is probably one of the large leafed or macrophylla types. These do not usually require much pruning except to remove any winter killed material. This can be done in late spring when you can tell definitiely which stems or parts of stems are well and truly dead -- they leaf out late so don't be too quick to prune. If pruning for size or shape, prune immediately after bloom. The reason for this is that they bloom only on old wood from the previous year. If you prune out live branches in fall or early spring you will remove buds for the next year's flowers. For tidiness you might want to deadhead each year, which means removing the spent blooms.
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