I bought an azalea, quite a decent size, last year and it flowered beautifully. I put it in a pot that had previously hadf a rhodadendrum in it which had died, there were hardly any roots on it when I took it out. Now the azalea has died. I have never azaleas or rhodadendrum before and don't know where I am going wrong. I used ericaceous compost and feed. Could it be something in the pot.