Unhappy Rhododendron?

Hi looking for some advice about the Cunningham's White. I bought 2 about a month and the pair are potted in the same soil and compost and had the same watering etc.

Both are placed in morning sun then shaded from early afternoon.

One looks much healthier than the other (pic 1) The other in the 3 pics has much more yellowing around the stems and has had quite a lot of leaf drop and browning.

Is this something to be concerned about? If so any tips what could I try to bring it back?

Any advice appreciated, thank you

 

I wonder if that one has come into contact with some lime either in the potting compost or the watering, maybe even before you bought it.
I'd give it a watering with sequestered iron, and see if it greens up.

 

Are they potted in Ericacious compost?

 

They don't need ericaceous soil or compost. If the soil is not alkaline, and is neutral to acidic that's fine.
Cunnungham's White is a very very large variety, and quite fast growing, so it won't like being in that very small container for long.

 

Most rhododendrons need acid conditions to grow (pH 6.5 to pH 4.5) this is the pH of bought ericaceous compost. If you are not sure about your soil and none of your neighbours grow camellias or rhododendrons, then I would use ericaceous compost from a garden centre.
Where I grew up in Lincolnshire the soil was alkaline and we grew good cabbages. Here my soil is pH 6 to 6.5 so I can grow some camellias and rhododendrons, other ericaceous plants would be happier with me having a slightly lower pH. I mulch with composted pine needles and use both sequestered iron and Epsom salts to keep these happier.
Ericaceous just means soil in which plants of the Ericaceae family grow happily.
As far as I can see Cunningham's White reaches 1.5 to 2 m in about 10 years, but I haven't grown it myself.

 

So basically ericaceous then?

 

The soil level looks very low in that box, so there isn't much to sustain it. compost is no use anyway for a shrub if it's going to be there a long time. You need a loam based mix for shrubs.

Cunninghams White got to 6 feet in a few years from a fairly small plant when I grew it. Easily four feet wide.

 

Thanks for the comments. Yes currently using ericaceous compost but will look into how to sustain further with feeding etc.
I'll top up and add some sequestered iron as suggested too, see if that makes a difference.
Thank for the tips, I'll update when thing change

 

Preferably Rain water too

 

There's variation within neutral soil though. It doesn't have to be terribly acidic soil for rhododendrons to thrive extremely well. It certainly does no harm to add some ericaceous compost, as long as the mix itself isn't just compost. Shrubs will use up the content of compost very quickly.

 

You can get ericaceous JI compost, but I'd still mix it with either peat or a standard ericaceous compost.
I was under the impression that there are a certain group of Rhodos that originate in North America which are lime tolerant.