After the amazing bloom of a large rhododendron, the spent flowers look messy.
According to the American Rhododendron Society (ARS) http://www.rhododendron.org/pruning.htm :
“It is desirable, with the large flowered rhododendrons, to remove the withered flower clusters after the blooming season. This is fairly easily done as the central axis of the cluster, usually called a truss, will break free from the plant with a quick snap of the thumb pushing on the side.”
It’s a simple, although tedious, job. I just snap the spent flower at the brown-ringed collar with my thumb and forefinger. Sometimes deadheading is impossible on a large shrub (without a ladder and arms like a gorilla).
I don’t stress about deadheading and I do as much as I have time to do.
ARS says, “Dead-heading is usually done to make the bush look more attractive, to reduce the prevalence of fungus and to prevent a heavy set of seed. If it is not possible to remove the old flowers, it is usually not too detrimental, but flowering the next year may be reduced.”
So, every time I pass the rhodys I stop and break off as many spent flowers as I can.