THey say you have to feed them magnesium sulphate, epsom salts. I have kept them going for years but then suddenly they will turn up their toes. They like quite a lot of fertiser as they are gross feeders, but I think the go would be to feed them with a liquid.. Charlie Carp or that yellow soluble one you buy in packets, and do it a bit at a time say each week. It may need repotting with fresh soil as the pot has probably got salted up if it has been there for a while. You could put a pinch of epsom salts in each time. Also they like an acid soil and the potting mix may have got a bit alkaline. That means they can't take up iron. I used dynamic lifter on mine and it died. he nursery person reckons that's what killed it as it is too much nitrogen but DL is not that high really. A little often I would suggest. Pam