I used Garden Planner 3 for all my large scale, from-scratch planning. It has a lot of limitations, but it did the job to scale like I needed it to so I knew things would fit together. This year I'm giving it a rest since I don't have huge rearrange-everything plans. I'm just sowing seeds and getting plants and bulbs ready. Whatever comes up I'll find a space and tuck it in. I'm not really a planner. Although I do like to sketch, I'm not good enough at it that it would be that realistic representation of the end result. I like to work these things out in my head and then on the ground. I see plants I like, get them or their seeds, and go from there.
