I wanted to try using rhubarb leaves as a way to imprint concrete stepping stones — so I did! All I needed was a large rhubarb leaf, a bag of inexpensive concrete mix, spray cooking oil, a piece of wire mesh, some sand, a piece of plywood large enough to use as a work surface, and a bucket with water for wetting the concrete mix.
I laid the plywood sheet in a shaded place, and then dampened the sand and gently spread it onto the sheet, taking care to cover a space slightly larger than the selected leaf. I added water to the concrete mix according to the directions. I then laid the leaf face-down on the sand and sprayed the back with cooking oil before covering it with 1 inch of prepared concrete. I patted it down to remove bubbles and then rounded the edges. To give it extra strength, I covered the damp concrete with a piece of 1/4-inch wire mesh before adding a second 1-inch layer of concrete. After patting down the second layer and rounding the edges again, I left the concrete to dry for several days. When it was dry enough, I overturned the stone and removed the rhubarb leaf with a soft wire brush. I also smoothed any remaining sharp edges. I let the stone dry completely before moving it to the yard. I’ve made five of these garden stones now, and they’ve all survived two harsh winters without cracking or breaking.