Dying Azalea

lynnetindall

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.

steephill

A lack of roots might mean vine weevil grubs have destroyed them. Were there any white grubs in the soil when you removed the plants? Otherwise it might be watering - either too much or too little. If there is no drainage then it could be too wet, drowning the plants.

Fairygirl

I'm guessing drought.
The most common cause of rhodies/azaleas/camellias etc not doing well in pots is lack of water. Factor in all the dry weather last year, and it's the most likely reason, but @steephill is also correct in saying that if the drainage isn't adequate, they can drown.
It's surprising how often we see plants, on the forum, in pots with no drainage at all.
They aren't usually affected by vine weevil, but if the plant is potted, and already weak - it's possible.
   
They need to be in a soil based compost too, and kept in a shady position to limit moisture loss. They also need an adequate size of pot. 
If you don't have soft water, it's also better to collect rainwater for them. 
A photo would help though 

lynnetindall