Best compost for container shrubs

I must admit I've always used John Innes 3 because it retains water well, and I always figured that that counterbalanced all the disadvantages of weight and clagginess.

But I'd like to know what others have found.

 

I tend to use a general multi purpose (or ericacious depending on shrub) and mix with 20% manure and 10% sand. That works for me in central Scotland.

They do take a bit of looking after though with extra feeding and watering where necessary.

My roses and Rhoddos are in 50l minimum pots and seem to do well.

 

John Innes for me every time.
John innes holds moisture and nutrients better than mpc I think.
However, I adjust according to the plant.
Most Alpines have as much as 50% grit or perlite added for example.
Greedy plants have dried manure, chicken pellets, compost added
Research what every individual plant needs and act accordingly I think Howard