Diamond Rouge is a paniculata hydrangea and in colder zones, they can handle full sun. In warmer areas, six hours of morning sun is ideal. Moving them to a sunny spot in the garden will help them grow larger. If you move the plants, add compost to the soil. Wait to fertilize until early next spring and look for one with a higher P (phosphorus) in the NPK ratio. High nitrogen (N) will grow leaves at the expense of flowers. The soil pH won’t change the flower color with paniculatas and isn’t as much of a concern.
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