I have an old rhodo, which is about 5 feet high by 10 feet wide. It's just loaded with gorgeous red blooms right now. However, all the blooms and leaves are at the ends of the branches, maybe 2 rosettes per branch. The centre of the plant is all bare, thin branches. How can I get this plant to fill in the centre? I don't want it to get much taller, and would like to see some new growth in the centre.
If it is infested with powdery mildew that will account for the gauntness and specimen should be sprayed instead of pruned. If it is too heavily shaded specimen should be given more light, if possible. Cutting back will not be likely to produce improvement if either of these occurrences are the dominant reasons for its current state.
There is no mildew or any other disease that I can see. It gets lots of light, east facing garden, with sun until early afternoon. I've read that you should look for dormant buds on the branches and cut back to just above those, but not sure what they look like.
Powdery mildew now pandemic down here. During years after 1990 winter it appeared many thought their plants were gaunt due to cold injury, apparently not having noticed the mildew at all. http://ipmnet.org/plant-disease/disease.cfm?RecordID=969 Leaves die and drop prematurely, causing specimens to be bare on inside. Most susceptible kinds may be defoliated nearly to the ends of the branches and die, while other kinds live on for years with a thinner than normal outer shell. If a planting site is too dark growth will reach for light and become quite open as well. Again, whacking back will assist with neither problem. In the first instance new shoots growing from stem buds may become heavily infested and die, leaving the specimen with dead branches. In the second instance cut-back branches will be made to be farther from the light source than they were before; re-growth will continue to produce same appearance as before if source of shade not reduced or eliminated.
