Rhododendrons: Rhodo leaves falling off

We live in the Sacramento area of Central California. We planted a rhodo in front of our house about three years ago. It gets some morning sun but is mostly in the shade during hot summer days. Close to house and under a tree so not much exposure to wind either. Now about 3 ft tall. Didn't bloom until 2/3 months ago (just an occasional blossom) after started feeding rhodo food. Plant seemed to be thriving w/many new shoots when I noticed about a week or so ago that leaves were falling off (the older leaves, not the new). This was a day or two after I last fed it. I picked up about 40 leaves yesterday and noticed a half dozen or so more on the ground today. I checked a number of web sites but found no mention of this type of problem. Any thoughts/suggestions as to what's happening very much appreciated. I'd hate to lose this plant.

 

It is common for the older leaves 2nd or 3rd year leaves to fall after new growth is established. I don't ever recally seening 4th year growth remaining. There is some variance depending on the rhody type. Also, older leaves are not a good judge of plant health, but if the new growth is green and health looking then you're probably OK ... I would keep up the ocasional, I assume liquid rhody food like miracid, and just keep watch. Rhodies respond well to leaf feeding that can hide an overall soil deficiency (or counter one depending on your view).

 

Check for rhododendron mildew.