My dear fellow gardener Julieh2, I did not mean that I objected to answering a question a hundred times, only that some people don't quite believe you can grow anything in a pot, and as I am a passionate believer in it, I keep banging the drum about it. I would be saddened if you thought I was being harsh to you, that never, ever, entered my mind - and if it happened I sincerely aopolgise.
You are quite right that potted plants do not reach their full potential for growth in a pot, however big that might be, though some certainly try! If you leave a pot with a potential tree in one place for a long while, the roots will find their way out into the ground below, unless you use sauscers or plates inderneath, I never do that so several of my trees are probably rooted far away from where I think they are! There is an acer that canot possibly be growing only in the pot is has been in for the last 15 years, but that's OK, I don't intend to try and move it anyway. The other thing is that it often means you can grow something that if it did grow to full size would be too much for your garden, but in a pot is more manageable - we have a 12 foot oak tree in a huge pot, I know it will never each the size of a woodland oak, but we love it as it is - so do the birds.
please keep asking questions of everyone as much as you like, we all learn something from eah other, and we all had to start somewhere- most of all, enjoy your garening.
Don't forget with hostas, that their natural growth as far as size is concerned, is very variable. I have some that are 2 inches high, and some that are several feet high and across - yours just may be a smaller typpe than that of your friend? Hostas are very satisfactory plants to grow in pots as you can keep the dreaded slugs off with copper tape around each pot, which reduces thae amount of damage those horrid pests do to them otherwise.
Please do keep asking questions, as much as you like, we all learn something new from these posts, and we all had to start somehwere, and were/are very glad of tips and help. Most of all, enjoy your gardening, 'tis the best thing ever!