Answer: Hydrangeas remain pink in alkaline soils and turn blue when the soil is acidic. It takes a while to change the soil's pH, but it can be done. If your soil is acidic, you'll want to sprinkle lime over the soil surface in the fall (it takes a few months to works its magic). If your soil is sweet, or alkaline, you won't need to do anything to keep the flowers pink.
Good luck with your garden!
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