I went on a nursery tour this week (more on that here if you're interested:
http://petiolejunction.wordpre...) and they showed us liner-sized plants. In terms of perennials, trees and shrubs liners are the same as plugs are to annuals--tiny little rooted starters.
There's a photo of some annual plugs here (
http://petiolejunction.wordpre...). These are next to 4" pots, so this gives you an idea of how small the plugs are. I expect it's about the same with hostas. If you get liner-sized plants you can expect the plant to take a year or two before it looks like the ones you'd see sold in a nursery.
