Hi My 3 year old rhododendron Mist Maiden is looking very yellow and looks stressed. I have added peat and food at the beginning of the season. It did not bloom (most of my Rhodos didn’t bloom this year.) but I have new buds coming up. Last September the house south of me took down a huge Linden and now it gets sun from about 11:00-2:30 do you think that is too much sun? Should I move it when it looks so unhappy? I am sending you a picture if that helps.
Rhododendron ‘Mist Maiden’ is described as best grown in part shade, preferring a sun-dappled or high open shade. It is possible that the adjustment to sunnier conditions is responsible for some of the stress your plant may be experiencing, especially as the sun is across the noon hour. It may make sense to monitor it through the summer months, and then make a decision as to whether to move it.
Peat is not generally recommended for rhododendrons, according to the American Rhododendron Society. Here is what they suggest:
A year-round mulch of some type of organic matter is desirable to conserve moisture and eliminate the need for cultivation. Because of their shallow roots, little or no cultivation should be done around rhododendrons. Weeds should be carefully pulled, or in extreme cases shaved off with a sharp hoe. A fairly deep mulch of leaves, pine needles, chips, bark or other organic material will practically eliminate weed growth. (Peat moss should not be used as a mulch because it sheds water when it dries out.) The coarser the mulch the better, as water and air are admitted while the mulch still retards evaporation by providing shade and reducing wind velocity over the roots. A mulch also helps to maintain a moderate soil temperature in the root zone.
Often yellowing leaves are associated with an iron deficiency, or with soil that is too alkaline for rhododendrons. It is worth making certain that your fertilizer is the correct formulation: the American Rhododendron Society recommends a complete fertilizer for acid-loving plants, to be applied in late winter or early spring, and notes that rhododendrons don’t require as much fertilizer as other plants.
Rhododendrons are very shallowly rooted and many of their problems occur because of either excessive irrigation, lack of irrigation, or soil quality: they perform best in well-drained acidic soil with constant root temperatures and consistent irrigation.
The American Rhododendron Society’s website is a great resource; clearly written and informative, and does include a comprehensive discussion on transplanting, if you decide that your rhododendron should be moved to a shadier part of your garden: https://www.rhododendron.org/.
The Missouri Botanical Garden also devotes a page to ‘Mist Maiden’ which is useful: https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=266524&isprofile=0&