Posted: 08/06/2017 at 20:46
Always do this with the alpines I have bought since it is often very difficult to get them to grow out of the rich compost in which they are grown for sale. Amazing number of times when a plant has failed and been taken out, and the roots are still in the original stuff.
Word of warning though. There are some plants (Daphnes for one) which absolutely hate having their roots disturbed like that and would definitely die on you.
Not so sure it is needed with every plant though. More often than not, just disturbing the roots is enough.