Yellowing of Rhododendron 'Kirin' leaves

Hello,

The leaves of my Rhododendron 'Kirin', which were dark green when purchased and planted last spring, have over the course of a season yellowed and have some black blotches. I wonder if they are lacking nutrients, or if I've got them in too much sun, or if there is something else going on.

Your help is appreciated.

 

Rhododendrons like moist, well drained, acidic soil. If the first and second condition are fulfilled check your soil pH.