Should you remove old blooms from rhododendrons and, if you should, which is best: to prune or snap them off?
Here is what the American Rhododendron Society says on the subject:
“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, or can be cut off with a hand pruner. With the smaller flowered rhododendrons and azaleas, dead-heading is labor intensive and and generally is not required.
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.”
I have several mature rhododendrons in my own garden, and I deadhead the parts of the shrubs which are easily reachable, leaving the other areas to their own devices. For me, it’s an aesthetic choice, and I would probably do them all if I could reach and if I didn’t get very tired of the task. (It’s hard to do well with gloves since you can’t easily feel the right place to snap off the flower head, but it’s sticky work without the gloves.) I’ve never tried pruning them off, because it seems less precise (leaves a bit of a stub), but if rhododendron experts approve (as indicated above), I may just try it this year.