Casting Leaves in Concrete

Why cast leaves in concrete? Well, why not? It’s fun, easy, and relatively inexpensive to do and when you are done you have a piece of garden art, a stepping stone for a path, or a small bird bath. You can use any large leaves like hosta, cabbage, rhubarb, burdock, or what have you. Some plants with huge leaves make dramatic castings and can be used as planters. They can even be painted to appear life like.

A friend told me about this a few months ago, so I thought I’d give it a try. The biggest expense is the bag of concrete, but that is less than $11.00 and you can make several castings with one bag. I use Quickcrete vinyl concrete patch because it dries fast and leaves a smooth finish. Some people also add coloring agents and fortifiers, but each extra item you add adds to the cost. The castings seem strong enough without concrete fortifier.

 

In addition to the concrete mix I used plastic wrap, something to mix in, something to stir with, rubber gloves, a dust mask, water, and a large pile of moist sand. Sand can also be bought in bags if necessary.

 

Here I’m using a hosta leaf. Since the ribs and veins are more prominent on leaf undersides, I put the leaf face up on the sand. To cast a leaf you need to think in reverse; if you want a bowl shape lay the leaf over a mound of sand. For an arched leaf casting, make a depression in the sand, and for a flat casting, level the sand.

 

Once I had the sand molded the way I wanted it, I removed the leaf and put plastic wrap over the sand. This keeps the sand out of the concrete and lets you finish the edges of the leaf.  The leaf should be face down on the plastic wrap before adding the concrete.

 

I mixed the concrete to a toothpaste or brownie mix consistency by adding water slowly so it didn’t become too soupy. Soupy mix will run off of the leaf. When I had the concrete mix at the correct consistency, I put some in the center of the leaf.

 

What is shown in this picture will be the underside of the finished casting. With my hand, I patted down and worked the concrete mix from the center of the leaf out toward the edges as shown. This is where the rubber gloves come in handy. The finished casting should be about 3/8 to 1/2 of an inch thick in the center and slightly thinner at the leaf edges. If it is a little thicker it will just take a little longer to dry. According to what I’ve read, the concrete on very large leaves should be up to about 1 inch thick.

If I wanted a casting you could hang, at this stage I would lay a loop of sturdy wire (like coat hanger wire) into the wet concrete and then cover it with more concrete. If leaves are bigger than 14 inches across it’s a good idea to reinforce them with wallboard tape or chicken wire at this stage so they don’t crack later on. Just lay the wall board tape or wire on top of the wet concrete and cover with more of the mix, smoothing as you go.

 

I gently pull the plastic wrap toward the leaf edges so the concrete mix doesn’t flow out beyond them. Peeking under the leaf as you pull the plastic wrap toward the center shows where the leaf edges are. This makes a nice clean edge. After I’m satisfied, I leave the casting just as it is shown for two days. If it’s supposed to rain, I cover it.

 

Once the concrete is dry, smooth surfaced leaves like hosta will peel away from the dry concrete easily. This picture shows the casting after about half of the leaf was peeled away. Hairy leaves like rhubarb or burdock may need to be scrubbed off with a wire brush after decomposing for a day or two. Some leaves might also stain the concrete slightly.

 

This is my first attempt at painting a concrete leaf that was cast earlier. It’s supposed to resemble a leaf from a green and white hosta variety known as “minuteman,” but for some reason this photo seems to have a bluish tint to it. Oh well-at least it shows what it is possible to do with leaf castings, and that’s the whole point. Next time I’ll use stiffer brushes and flat paint. This was done with foam brushes, which made getting sharp edges difficult. The satin paint also seems a little too shiny for my tastes.