This fall the leaves on both of my rhododendrons are turning from yellow to brown and black with holes in centers. The edges also have gray powder looking stuff on leaves. These plants are about 10 years old and were transplanted a year ago in the fall.
It sounds like a sooty mold problem, brought about by insects. Neem oil is an effective treatment. Here is more information: https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/rhododendron-sooty-mold.htm
I have a four foot tall Rhododendron that is trapped between two trees and has NO width. I want to transplant it to an open space close by where it will have room to fill out. Problem is it did not start to bloom until late last fall and it is still trying to bloom and has most of its leaves now. Once the new spot is prepared, can I dig down and try to get most of the root structure and move it? Thank you very much for your input.
I would move the shrub in early spring when the weather is fairly mild, getting as much of the rootball as possible, or wait until the following fall. This article will help with planting the shrub: https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/rhododendron-care.htm In order to reduce the amount of stress on the plant from moving it, you may want to consider cutting it back. This will likely affect the blooming but will up the shrub's chances of survival and it will always put out new blooms the following season. To help with this and transplanting, here is more info: https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/pruning-rhododendrons.htm, https://www.gardeningknowhow.com/plant-problems/environmental/learn-how-to-avoid-and-repair-transplant-shock-in-plants.htm
The buds are still on but did not open. I did not take them off in the fall. Should I remove now (early spring)?
I would leave it alone. The plant will shed them when it is ready to and removing them will unnecessarily expose the plant to the potential for disease.
Can you plant rhododendron bushes in heavy clay soil? Don't have anymore to say.
Heavy clay soil would need amendment to grow rhododendrons successfully. This article will help you: https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/rhododendron-care.htm
My rhododendron has lots of buds, but the leaves are all dried and crispy, no green anywhere. What can I do?
It likely is winter burn. Rhododendrons normally will regrow their leaves and recover from it. Here is more information: https://www.gardeningknowhow.com/plant-problems/environmental/winter-burn-in-evergreens.htm
I have a small rhododendron bush. Over the winter, I think my dog urinated on it, especially on one side of it. Now that all the snow is gone, I see half (where he urinated) of the bush seems to be dead... no leaves, bare branches with no growth. The other half has some green leaves and buds as well as some leaves that are partly brown and droopy. First, has the dog's urine damaged the bush, and secondly, what should I do with it now? Should I cut away the bare branches and hope to save the rest of the bush? Help!
The urine may have made the soil too acidic and salty and it will slowly kill the plant. Really, the best thing to do is to flood the area with the hose. This will help wash the urine out of the soil. As for the plant, check the stems to see if they are still alive (https://www.gardeningknowhow.com/plant-problems/environmental/how-to-tell-if-a-plant-is-dead-and-how-to-recover-an-almost-dead-plant.htm). You can remove the stems and branches that are dead.
I have two rhododendrons which I have to move due to a building extension. They are in full flower now (May). The building work will start approx. September. So when shall I move them? As I understand hot weather is not ideal. Also to what kind of spot would suit? I have warm/dry or cooler/damp parts of garden.
I would go ahead and move them if the weather is still fairly mild, so transplant now, getting as much of the rootball as possible, or wait until fall. This article will help with planting the shrub: https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/rhododendron-care.htm In order to reduce the amount of stress on the plant from moving it, you may want to consider cutting it back. This will likely affect the blooming but will up the shrub's chances of survival and it will always put out new blooms the following season. To help with this and transplanting, here is more info: https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/pruning-rhododendrons.htm, https://www.gardeningknowhow.com/plant-problems/environmental/learn-how-to-avoid-and-repair-transplant-shock-in-plants.htm