Answer: Some hydrangeas bloom on new shoots which develop on old wood, and some bloom strictly on new wood. Those that are best adapted to your area are the kinds that, even if they freeze all the way down to the ground each winter, will send up new canes and each will bloom. Hydrangea macrophylla, the common garden hydrangea, blooms on new shoots which develop on old wood. As such, the oldest wood needs to be protected from freezing or you'll never get blossoms. With that said, all hydrangeas bloom on new wood (whether or not it develops from old wood) so some pruning is necessary, unless you have plenty of space for the plants to sprawl, and you don't mind bare centers in your plants. You can prune these guys down to 18 inches in the late fall and cover them with insulating material to keep the old wood alive. In the spring, flowering shoots will develop from the short canes that you left. The other types which freeze down to the ground each winter will develop new flowering shoots each spring so cutting away the old dead wood is a good practice. It's true that too much nitrogen fertilizer can retard or even eliminate flowers so be careful with fertilizer. Hydrangeas generally are not heavy feeders anyway, so don't feed unless the foliage is off-color. For best bloom, hydrangeas should receive at least a half-day of direct sunshine. If your summers are hot, provide morning sun and afternoon shade. If your plants are not blooming, and you haven't pruned them, you may need to relocate them to a sunnier area. Best wishes with your hydrangeas!
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