A few, such as A.candidissimum , are grown in the open garden. In all cases they will benefit from deeper planting in colder areas. Partial shade is very beneficial. Soil or compost should be humus rich and moisture retentive whilst being well-drained. River sand and leafmould are essential soil conditioners.
Some growers like to surround the tubers with sharp sand or Cornish grit.
I do not practise this, as I feel that it all too often creats a sump around the tuber in just those conditions where the plant needs good drainage. I feed regularly. Ignore advice that says bulbs do not need or benefit from Nitrogen, of course they do but it must be given when the leaves are developing . Once the leaves are fully formed then they do not benefit from feeding extra Nitrogen and too much then will indeed be detrimental. They do need plenty when they are forming.