Hi Spiderlod and welcome to GoY. You need a compost that is free draining and not too rich, I'd mix one part grit to two parts multi-purpose compost. There are holes in the bottom of your sink I take it.

thanks for the info this old stone sink has a plug hole that should be ok for drainage.....thanks again

If it only has the one hole I'd put a layer of course grit at the bottom to help drainage and have the end of the sink that doesn't have the hole a millimetre or two higher than the end with the drainage hole. Alpine plants, in general, do not like sitting in wet soil.

Definitely need to raise the sink off the ground

Also helps if you can put a piece of aluminium net over the hole. (The stuff they sell for mending car bodywork). This helps keep the hole free and stops worms entering that way.

Hi

I know it sound drastic but most alpines are grown in either peat or multi-purpose compost WHEN YOU BUY THEM , and over the winter holds the water right next to the roots which they hate and either end up killing them or making they look very unhappy with the growing conditions , my brother worked at Kew Gardens and any new plants bought (Alpines) in they would wash the roots clean of any compost and then plant in Johninnes no2 (you can get at the garden center) and this would be mixed with grit , a 50/50 mix of both and then top dressed with a grit once all planted up.

Very rarely they would lose any over the winter

Gg

http://www.growsonyou.com/Owdboggy/blog/19510-planting-up-a-trough
As this shows.

I agree wit GG was all the soil off the plants you buy in pots from nurseries and garden centres and only then plant in your sink.

Don't do it to Daphne or Pulsatilla though, they hate root disturbance like that.

Unlikely to be planted in a sink even with Daphne if it had been grown in almost pure peat I would try to remove as much as possible without disturbing the roots.

I have a sink with a Daphne cneorum in it, drapes beautifully over the edge.