I planted one years ago between sidewalk & house. It never really blooms. It begins, then the "flowers" go black & the leaves begin to turn black. I'm thinking of moving plant somewhere else. When should I do it? And, what do I need to do to help it bloom?
Certified GKH Gardening Expert
Before you move it, though unless it is in the sun you shouldn't have to, make sure to treat the infection so that it doesn't get spread to the new area, as well.
A fungicide will do the trick. This article will help: https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
This article will help you to know what Hydrangeas need in, in general, to be healthy: https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/growing-hydrangeas-hydrangea-care-guide.htm
As far as the blooms go- if all environmental factors are taken care of, including testing the soil for too much nitrogen, or a lack of phosphorus and potassium, making sure that it doesn't get too much sun, and making sure that it has a chance to dry out thoroughly between waterings, then you might chalk this up to being right outside of the range of that particular cultivar.
This article will help you to address the flowering issues: https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/hydrangea-not-blooming.htm