Rhododendrons: rhododendron stopped blooming

2 different folks have asked if I know how to correct a problem with their rhodos(One is Nikko blue, I believe. The other is a small leaf version-name unsure) that stopped blooming after about 2 years. The bushes are large and in ideal locations around other healthy acid lovers. I don't think they're pruning at all.

Is it normal for some species to only bloom 1-2 years? Is there a way to reactivate their blooming?

Appreciate any guidance.

 

'Nikko Blue' is a hydrangea, of course. Colder winters could kill the flower buds on this or a rhododendron, if you have been having some hard ones lately that is a possibility.

 

Many Rhodos can be arbitrary about when they will bloom, while others will reliably bloom year after year.

I have one large hybrid that bloomed once after planting (and turned out to be something totally different than it was supposed to be, but was nice enought that I didn't exile it to rhodo purgatory next to the street as I wanted to see it bloom again) and hasn't bloomed in the 3 years since. I see buds now, so maybe next Spring....


With some species Rhodos, they switch into vegetative growth when conditions are too good and bloom only when threatened by poor conditions (or when they mature, sometimes many years in the future). If you see a plant that hasn't bloomed much all of a sudden bloom lavishly, look for a soil problem!

Another thought it to take a look and see if flower buds are forming now. Sometimes disease can blight all the buds and even though they form, nothing comes out in the Spring - the buds rot and no flowers.