I don’t know if anyone can advise me. I have 2 Summer Summit rhodos which are around 8 ft tall and very healthy but they don’t flower and haven’t done so for the last few years. They are in a bed with other rhodos most of which flower every year although the sutchuenese which is next to the Summer Summits only tends to flower well alternate years. They are in partial shade and are fertilized with rhodo food at least once a year, twice if I have time. I do water them but only a couple of times during a dry summer as we are on a well and have to conserve as much water as possible for other parts of the garden. The front of the border where the rhodos bloom well is next to a gravel path, the back of the border where the Summer Summits are is raised 6 landscape ties high and as a result I try to give these more water than the rhodos at the front of the bed. As they are at the back of the border, it would be difficult and very expensive to take them out and replace them with rhodos of a similar size. Does anyone have any suggestions to get these rhodos to flower? I have so far been advised that they get too much fertilizer, not enough fertilizer, too much shade, not enough water.
Lack of summer water and rhododendrons is not a good combination. Are they wilting in summer? You won't have them bud up well if the site does not suit them well. I don't know this cultivar, but we have had some low temperatures in recent years. Maybe the flower buds are being killed.
Many in local plantings are producing a sparse appearance, smaller leaves and fewer flowers due to widespread, virulent powdery mildew.
These Summer Summit rhodos are late flowering. They are healthy and have never shown any signs of wilting due to lack of water nor mildew. All other rhodos in the garden are doing well, some of which receive even less water during the summer dry spells. I had hoped that someone might be familiar with the variety Summer Summit. It continues to be a mystery as to why they don't flower.
http://hirsutum.info/rhododendron/hybrids/detail.php?start=S&id=18332&offset=900 Here is some info on the parentage of Summer Summit, might help. If there is a rhodo group in your area you might try contacting them for advice. I see someone already mentioned too much shade/low bloom count. Could you limb up other trees around them to give them more light? I know some of mine which are in the most shaded areas of my garden do not bloom as well as the ones that get more light or even direct sunlight.
I read some-thing a while ago that reported some Rhodos. are all male and won't flower. They turn male...I can't recall why. I literally have thousands of magazines and reference books, trade journals. If I can find it, I can post it....but this is what I have read.
Rhododendrons produce perfect flowers. "Male", in the context of calling a tree or shrub that is used in reference to kinds that produce imperfect (unisexual) flowers, such as those of hollies and Skimmia japonica. Male forms of these produce pollen-bearing flowers only. A better term for what you appear to be talking about might be sterile.
Re: R. auriculatum? If so it could very well be the fact it does not bloom till July and we are off to a late start this year. 'R. auriculatum' are late bloomers and flower and develop new leaves in the heat of the summer. Are the buds forming and then drying up in the heat? I agree with Ron B in regards to summer water. If it is 'R. auriculatum' it can be hard to find.Did you purchase it yourself? how deep is it planted? Fertilizer may not be needed in you neck of the woods or for this species, mabye just a bit of bark mulch to keep the soil moist. If you really want to fertilize it I recomend peeing on it starting in March and stopping in May.