I bought gallon sized plants from a local non profit nursery and upon closer examination, I can see that there are at least a dozen plants in one pot. I'd like to break the slips apart and plant them all around an area that I'd like to fill in. How rapidly will this grow and how much/far can I expect it to spread out?

I also have a type of ajuga that will also be mixed into this bed. I am ok with a dense cover when it all gets growing.

any thoughts? suggestions? warnings? :)