As Rita said, it doesn't have to be anything fancy at all. In fact you could just do a rough outline of how your bed looks and then put numbers, maybe left to right with row 1 in the front, etc. And then you could list down below by row and then each number the name or seedling number that is planted there. I get these cheap plastic clipboards in the school supplies section of WalMart and take some printer paper out and sketch/write away to start the process, and I think that's the quickest way to do it. But then I, of course, am totally obsessive about it and try to finalize my maps (would you believe I have over 400 irises now?) and make them look pretty after I get everything planted and settled down in the fall/winter when I have time to play.