Trish, it's too bad you don't have time to write a book called "Gardening with Babies" - It would be a best seller.
We had two December babies so by the following summer, they weren't walking but sitting up well. I had an old galvanized tub my mother used from her wringer washer. If it was hot enough, I would put the tub near where I was working and put some water in it with cups and spoons and they would play in there for what seemed like hours. I'm sure it wasn't that long but it entertained them for a good long while.