Hi Caroline! Have you looked at Wrightman Alpines on-line catalogue? I bought a dwarf, hybrid wallflower from Wrightman Alpines in 2004, planted it in my gravel garden, and it lived and flowered for 6 years. It was Erysimum 'Turkish Delight'. I just checked Harvey Wrightman's current plant list, and he isn't offering 'Turkish Delight' any more, but he does list two alpine Erysimum species with yellow flowers.
