Where I live it is 1100 meters above sea level and we even get snow falls in winter. These pictures were taken in my garden in the Spring of 2012. I use very little fertilizer
Sometimes heavy rain during flowering can saturate the flowers and cause them to droop very quickly. With the Rhodos it is also important to note that some years you may get very little or no flowers. I asked my local nursery about this and they said that it is perfectly normal as sometimes the plants just need a rest.