Answer: Hydrangeas can get well over 6' wide if not pruned regularly, so it should be at least 6' away from your house. If you plan on keeping it smaller, you can plant it closer to your house, but you'll want to give it at least 12-inches of air circulation space between the ends of the branches of the plant and your home. If the hydrangea is too close, it can damage your house by holding moisture against it, and the plant itself can be disease prone because of lack of air circulation.
Best wishes with your new hydrangea!
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