With their smaller root systems, I've found dwarf selections to be much less forgiving of irregular watering compared to the larger varieties that I've grown. 'Moerheim' & 'Patty Bee' have both succumbed. On the other hand, 'Ramapo' (I don't care that much for it's growth habit) and the wonderful 'Ginny Gee' have hung in pretty well. I made the mistake of planting a number of PJM's in fairly shady areas where they have never bloomed. Ditto for 'Baden-Baden'. Not really a dwarf, but I highly recommend 'Golden Genie' if you're in the market for a nice yellow selection.

We've had a Shamrock growing in mostly shade on the northside of our house since 1985. It does well with very limited water and it is wonderful to have the pale green folowers out on St. Patricks Day which happens every few years. It is a prolific bloomer. jwww

I am fond of mine too, it grows next to my waterfall. It doesn't splash so it is really a dry area.

I'm not sure if the photo labeled Baden Baden is really Baden Baden. I had Scarlet Wonder and Elizabeth also. I ripped out one of the reds as a non bloomer and one died after I moved it too close to summer. I don't know which one is left....

Tolerance ranges more likely to be determined by genetic backgrounds than height range categories. In Yunnan dwarf Rhododendendron racemosum grows all around spots of dwarf Rhododendron hippophaeoides. The spots of the latter species are where there is a depression that has moister soil. Same height category, same overall environment but different moisture regimes.