This is a dead plant I found in a client’s garden, it was in effect trying to grow in a pot sized volume of soil as it’s roots just kept spiralling round.
When choosing a plant hold the pot up and see if roots are coming through the drainage holes. If they are, hold the plant by the stem near the base, and tipping the pot tap it – you will be able to lift out the whole rootball to have a look. If it is obviously grown into a tight whorl reject the plant, it could end up like this one. If it isn’t oo bad – the roots are reaching the edges and maybe beginning to curl, then take it. It is always advisable when you plant to gently tease out some of the roots to break up the pot shape and encourage it to grow outwards into fresh soil.