[hubballi]

My rhododendron has been healthily growing in a pot for a few years in ericaceous compost. I potted it on into a larger pot and had a little of the ericaceous compost left in a bag so mixed in some soil and normal compost AND a lot of pine needles to add more acid. Over 2 weeks on and it looks a little yellow and some of the leaves have dropped off. I keep giving it a watering now and again. It isn't vine weevil as the roots were very healthy and completely fitted he shape of the old pot.

[spottymint]

The soil & normal compost will be no doubt, alkaline ( not acid) which rhododendrons need.

Repot it in the correct compost, try feeding with proper rhododendron feed with cheleated iron & if possible, use rain water, not hard tap water.

In the wrong soil, rhodo's can't take up food & iron, hence they go yellow, look sick & eventually die.

[hubballi]

But I did add loads of pine needles to make up the acidity.

[spottymint]

Pine needles will take an age to breakdown & acidify the soil.

Only way to know, is test the soil. kit or tester just a few pound from wilkos/GC.