I'm thinking of taking my large rosemary plant up and
putting it in a large pot on my deck. I don't want to mess it up/lose it. Will this work? Can I do it now??
I don't think I'd move a large plant of any kind if I didn't have to. You might be better off buying a new plant already growing in a can for your deck arrangement. Or, if your large Rosemary has started growing roots off one of it's branches you might try cutting it off the mother and transferring it instead.
Of course, some of what I've said depends on one's definition of what is "large."
After seeing how large the plants this gives me the idea of putting mine in a pot. I just bought one a few days ago. I want to make my entire garden for herbs and I have a feeling this plant will take over once I put down the oregano, thyme, sage and basil.