What is the best stuff to plant lillies and stuff?

Unscented cat litter.

Loam? Gravel? What mixture of stuff do I use? Better yet...what the hell
is loam?

Loam:
1 a : a mixture (as for plastering) composed chiefly of moistened clay
b : a coarse molding sand used in founding

2 : SOIL; specifically : a soil consisting of a friable (:easily
crumbled or pulverized) mixture of varying proportions of clay, silt,
and sand