Hello, I've recently moved to a new house with a rhododendron that I just pruned last week after it flowered. I suspect it's about 18 yrs old. It was about 6 ft high and I pruned it to about 4ft. I would still like to take it down another 1 ft. at least but am not sure if that is advisable now. It would take off a lot of the leaves and would leave a lot of bare old wood exposed. It's quite leggy all over. Should I prune it further now (early June) to promote new growth during this summer/fall or wait a year? How aggressive can I be now? I realize it may not bloom as much next year but I just don't want to kill it! Thanks for the advice. (I live in the Woodburn Oregon area.)
Marion County Oregon
Thank you for contacting us about your rhododendron.
If you have already taken the plant down by 2-feet, you are right in being careful about further pruning. In most cases, no more than one-third of the foliage should be pruned off a shrub in any single year.
That being said, rhodies have been known to withstand severe renovation pruning and sprout back. From your photos, some longest stems appear to be bare except for a few leaves at the terminal end. Prune these all the way back to the source branch. (This is referred to as a thinning cut as opposed to a heading cut which merely shortens the stems.) This will allow more light and air in the center of the plant while also reducing the size.
This article should provide some useful information about pruning rhodies. If you have questions after reading it, please feel free to respond to this email.