Iris are a genus that do well here in dry east Fife. I grow many of them in a bulb frame that can be covered in winter -  but usually is not. Others like it really dry and I grow these in a deep made up bed in a large greenhouse with alkali soil and a great deal medium coarse grit. They are kept pretty dry year round and not watered at all in winter.

 This is Iris nusairiensis in an alpine bed inside the green house. It has slowly multiplied up but I have given too many away! It is described from the Jebel Nusair in Syria

This is Iris vartanii. This is from a similar area but also including Israel. The species is normally a pale blue but I suspect that this is not currently in cultivation - only this white form. It slowly multiplies in a very sandy bulb frame and was grown from seed.