Olive is good. It usually mean an older leaf. They are bright green when young, then darken as they get older. One way to get a quick improvement in leaf color is with Magnesium Sulfate (Epsom Salts). It will usually add a nice green glow to plants and is a good tonic to use once in a while. Good fertilizers like HollyTone contain .5% Magnesium Sulfate.

Yellow or mottled is bad. Yellow usually mean some nutritional challenge and mottled usually indicates a fungus or insect problem.

If you aren't getting any new leaves, it may be time to do a little fertilizing, mulching, and making sure they don't have too much shade.

Here is a link that might be useful: How to care for rhododendrons

Hey, thanks! I know enough about plants to know they're doing pretty well, but I didn't understand the distinct "olive" color and after seeing nursery plants began to doubt my own powers of observation.

So... what is it about "fresh" nursery stock that gives them the deep, rich green I always picture when I think of Rhodos.? do the growers give them regular Epsom Salt drenches to make them more appealing to people (like me) who have preconceived notions of "health" and vigor? What do you consider to be the "range" of healthy leaf color in Rhodos. and does the variety tend to dictate the range (I'm guessing it does)?

Should I try the Epson salt thing now or wait until after flowering? and is this a yearly "tonic" or should it be used sparingly? OR, do I need to go back and REread what you linked in your reply? ;)

The leaves in the garden center are new. They will also get that olive green look next year. Your olive green leaves are older. Your plants should be putting out some new green leaves also. If you aren't getting any new leaves, it may be time to do a little fertilizing, mulching, and making sure they don't have too much shade. Typically rhododendron leaves last about 2 years. They start out nice and green and end up more of an olive shade. Garden center plants are sometimes less than 2 years old.

I "took the long way home" today. It is a lovely seaside ramble past many, handsome homes with magnificent rhodies, many in full bloom.

I noted, with interest, the "olive" green leaves on some. I've noted that Nova Zembla doesn't seem to have any new leaves "happenin'"... I'll sit tight and then give her a shot of fertilizer after the flowers.

Thanks so much for patient advice. :)