my Rhododendron
had red blooms until last year when it blossomed with half the blooms red and half the blooms purple. This year all the flowers are purple. what would the possible reason be for this.
I would think it is to do with the acidity of the soil. Rhododendrons like acid soil and if the soil is not acid enough it can change the colour of the flowers. Try feeding it with an ericacious fertiliser if planted in the garden or re-potting it if in a container.
It may have been grafted on to a more common stock and has reverted to the common and far stronger purple due to adverse conditions or lack of nutrients.