I got 2 Rhododendrons from my Mom-in-law 2 years ago and they bloomed beautifully the first year. The second year they stayed green, no blooms. I'm guessing I overfertilized them according to my research. Will they bloom again? Or has the overfertilizing damaged them permanently? They have lots of green buds on them right now, (year 3) so they are very alive, but no flower buds. Might be a bit too early. They were about 3 feet high when I got them from her. She had them behind a fence and they were tall and gangly looking, as if they were reaching for the sun. My next question is... Both the Rhodos are very leggy looking and need a huge pruning because they are getting too tall. There are only leaves covering the top portion of the plants, not the sides or middle at all, so I'm wondering if I can cut them right at the bottom, maybe 6 inches from the ground and have them start a whole new growth for next year? I realize they can't be pruned till June or July, but the main branch is about 3 inches thick in diameter, so it would be a little stumpy looking for a while, but I'm wondering if new growth will still come from that? Thanx!
Sample soil and have it analyzed before fertilizing again. Examine leaves for rhododendron powdery mildew. This is a very common cause of a sparse appearance in this region. Heavily infested leaves are killed and drop prematurely. http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=969
Actually the leaves haven't dropped at all, and I have checked for powdery mildew, bugs, etc. The leaves haven't even dropped from last year yet because we've had such a mild winter. Or do the leaves normally stay on year-round? In any case, there's no sign of disease. All the leaves are a very healthy green and very healthy looking.
I wouldn't prune back more than a third of the plants and yes, do it right after blooming is finished.
Oldest leaves shed in summer or autumn, every year. Pruning tolerance varies with particular variety, some are not very tolerant and will fail to sprout from old wood. Others will come right back even if cut to the ground.
First, I wouldn't prune these untill you are sure they are established -- doesn't sound like they are yet. Second, I would consider Rons advice when you do. Now if you see what looks like buds starting on leggy limbs, then it may respond to trimming ... and may start to fill in without trimming as well. There can be a number of explaination for the budding issue -- check for buds this fall.
