PJM Rhodo leaves turning yellow/red

9 years ago

The leaves on my PJM rhododendron are turning yellow/red (see picture). I'm not sure what is causing this or what (if anything) I should do to about it. Advice would be greatly appreciated!

The shrub is about three years old. For the first couple of years, it was totally ignored. I transplanted it early this spring to a full sun location (8+ hours of sun per day). I pruned away all the dead branches after it finished flowering and have been giving it a good watering once or twice a week, depending on rain.

The new leaves that grew this year seem to be in good shape. They are still bright green and not at all wilted. Over the past couple weeks, next years flower buds have been growing and also look good and healthy. However, all the older leaves turn yellow, then red and fall off. Is this normal? What should I do?

Comments (3)

gardengal48 (PNW Z8/9)
9 years ago
How much shade was this plant in previously? Full-on sun is not a very good location for most rhodies in a zone 6 climate, especially with what appears to be a large boulder behind that may be reflecting heat. While PJM is considered to be a more sun tolerant variety, I believe the recent move to a more exposed location is causing stress. I would like to tell you the plant will eventually acclimate to the new location but I just don't have that experience for your area.

All you can do now - with the exception of moving it again, which I'm really not sure I advocate either - is to make sure it gets enough water during the heat of the summer. And you could consider rigging up some sort of temporary shade structure during the hottest part of the day.
akamainegrower
9 years ago
A midsummer move from shade to full sun will, as gardengal wrote, stress just about any rhododendron. The older leaves are going through the normal process of senescens - changing color and dropping - earlier than normal. This year's growth also shows the classic signs of insufficient water. This may be due to not enough water or a significantly reduced root system due to the move.

Established PJM's will put up with just about anything in Z6 and most of Z5, including full sun all day long. There's about a zillion of them adorning the parking lots of every MacDonalds, Burger King, Walmart, etc. Here they endure reflected sun, heat and not-so-benign neglect year in and year out and still put on a show every spring.
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rhodyman
9 years ago
I agree with akamainegrower. PJM is fairly unique in that it tolerates sun, shade, heat and cold. It is tough. Right now it is on the dry side due to the transplanting and is shedding old leaves earlier than normal. It is getting ready to put on a good show next year. Keep your eye on it if you get a dry spell. If the new foliage is wilted early in the morning, it is probably too dry and needs water. Wilted foliage in the heat of the day is normal and will recover.