This is a neat idea if you have a 3 piece picnic table. stack the benches, add some boards to the sides and you have a nice potting bench.
This old house has over 20 smart home solutions like this all together in a slide show. I like the benches acting as shelves on the potting bench a lot.
Turn a Picnic Table into a Potting Bench
Potting Bench: Downloadable Woodworking Plan
Cedar Potting Bench with Soil Box