Hosta gardeners are clearly obsessed with size and I can understand this from my own gardening experience. A four foot tall Gentle Giant sitting out in, or standing out in, a hosta bed is a tantalizing thought.
Sum and Substance Hosta (32″T x 72″W) and Blue Angel Hosta (32″T x 70″W) were the big two in popularity among the hosta giants for a long time. And they still are popular. No hosta garden should be without them.
The giant hosta Dream Weaver is a personal favorite due to the contrast of the blue-green border and the creamy-white center.
How large a hosta can reach in size is not only determined by the cultivar you choose.
Location has a great deal to do with its ultimate size. Giant hosta plants need unlimited water and a deep rich soil, more so than the smaller cultivars of hosta.