Container grown rhododendrons
I have two 20 year old bushes grown in half barrels (40 cm diameter) which are looking sad this year. Can I cut back roots and pot back in same tubs as I have done with pot bound camellias?
Yes you can. Here's an article with some tips on growing shrubs in containers that might be useful to you. https://www.gardeningknowhow.com/ornamental/shrubs/shgen/potted-shrubs-growing-shrubs-in-containers.htm