Hiya, lilly bulbs are available now( at most good garden centres--- and b and q). Can buy them for planting later. Lillys actually are water loving flowers--especially large flag lillys, and naturally occur around ponds etc.
Smaller varieties will thrive in dry gardens however, but like with all good things,, they flower brighly and disappear quickly.
Iris is hebrew for "rain bow"----so there you go!!