re: Fertilizer for Hydrangeas

The plants would be able to use it. My grandmother used to just drive an iron stake or rebar around her hydrangeas if she wanted to change the color. My last regular hydrangea finally froze all the way out over Winter. We took down a shed that blocked it from the north wind, and it just wasn't able to handle it. We got a couple decent years, but it faded every year after. The oak leaf hydrangeas are still going strong, though.