These are divide into three types, hardy alpine, non hardy alpines and woodland
1 hardy alpine, ideal planting conditions are a sharply well drained soil in full sun, or semi shade. As an additional precaution when planting slant the corm and introduce a bed of sharp sand underneath.
2 Non hardy MUST be kept in a bulb frame or alpine house. During its dormancy it must stay dry.
3 Woodland types require a peaty acid soil and slanting the corm will help in very wet areas. Additionally C Cava will rot if allowed to planted flat, due to its cave like form.
The majority available in garden centres and nurseries are woodlanders. And therefore require good coverage of shade during summer. Many would prefer to be in a well drained moist slightly acid soil. If you can introduce a micro climate where water in the form of ponds or artificial stream this would be ideal.
As a hint I have found that if you incorporate a mister near to the plants this will give them the required climate. And this year (2010) with only 1/2” of rain in three months this has kept the collection alive.
On no account allow the rhizomes to completely dry out because they will shrivel and probably die.
Other herbaceous types will require some shade and so you will need to keep an eye on them especially in mid summer.