How to Make a Hypertufa Garden Trough

English farmers of the 1800s used to chisel feeding troughs for their animals out of local granite and sandstone. Years later, creative gardeners adopted these old containers, covered in moss and worn by decades of exposure to the elements, as decorative planters. Few of these sought-after antique troughs are still available—and even if you could find one, chances are it would be too heavy (and expensive) for you to transport it across the Atlantic. But there’s a quick and easy way to replicate the weathered look of these hand-hewn vessels yourself.

The key is a material called hypertufa, a mix of cement, peat moss, and perlite, products readily available at any home or garden center. The name comes from tufa, a natural porous rock that looks much like weathered stone. Combine the ingredients, add water, pack the mixture into a handmade mold, and set it aside to cure for a couple of days. When you pop off the mold, you’ll have created a bit of the Old World, right in your own backyard.

You can build a hypertufa garden trough in a weekend and enjoy its beauty for years to come. In fact, the older and more weathered it gets, the better it looks. Here, garden expert Ken Druse takes us through the process, from casting to planting.

Step 1

Building the Form

Building the Form

Trough forms can be made from plywood, rigid foam insulation, or two cardboard boxes, one inside the other. We used pine shelf board because it is sturdy and can be used again and again. To create the decorative recess, we glued beveled panels to the insides of the exterior form.

Our trough measured 17 inches wide by 24 inches long by 10 inches high. You can use the same method to build any size trough. For best results, the walls should be a minimum of 2¼ inches thick, and the trough should be at least 7½ inches deep.

RECIPE

The amount of hypertufa mix you will need depends on the size of the trough you’re making. You can stretch or shrink the recipe if you stick to these basic proportions:

• 3 parts cement

• 4 parts peat

• 4 parts perlite

• Water sufficient to make a firm, moldable mixture, plus a splash of liquid acrylic (about ¼ the amount of total liquid)

• A handful of nylon reinforcing fibers

Step 2

Apply Release Agent

To keep the hypertufa from sticking to the form, the wood must first be coated with a release agent. (For instructions on making the form, see the overview page.) You can use petroleum jelly or a piece of plastic sheeting. We brushed on a layer of melted paraffin. Later, any paraffin residue on the trough can be easily removed with a wire brush or flat putty knife.

Step 3

Create Drainage

To ensure proper drainage, you’ll need to create holes in the bottom of the planter. Do this with a paper-towel spool or lengths of PVC pipe, cut into four 2½-inch-tall pieces and spaced evenly toward the corners of the outside form. Use some of the melted paraffin to secure them.

Step 4

Mix Hypertufa Ingredients

Wearing gloves, dust mask, and goggles, mix the cement, peat, and perlite in a large tub or trough. (For quantities of all ingredients, see “The Recipe” on the overview page.) Add the water and acrylic fortifier a bit at a time, turning the mix thoroughly so it sticks together but is not runny. Fluff up the nylon reinforcing fibers and add them to the mix. You should be able to form the fiber-reinforced mix into a solid ball that doesn’t fall apart.

Step 5

Pack Hypertufa Into Form

When packing the hypertufa mix into the form, take care not to knock the drainage molds out of place. Pack the mix tightly, starting with the bottom. When you’ve packed the bottom to a thickness of at least 2½ inches, insert the inner form and begin packing tightly up the sides. Shovel the mixture in with a garden trowel. Remember, the tighter you pack, the stronger your trough will be.

Step 6

Tamp Down Hypertufa

As you pack the hypertufa mixture up the sides, periodically tamp it down with a flat piece of wood to get rid of any air pockets. Continue adding and tamping until the mixture is flush with the top of the outer box.

Step 7

Remove Trough from Form

The trough will need at least 24 hours to cure enough to unmold. When you can’t scratch the surface with a fingernail, it’s ready. Remove all the fasteners and take off the bottom panel. Then remove the outside walls, popping the boards free of the paraffin with a garden trowel. Push the walls of the inside form toward the center so they collapse inward on themselves.

Step 8

Finish and Wrap

When first unmolded, the trough can be textured. By going over the surface with a coarse wire brush and knocking down any sharp corners, you can add hundreds of years of “weathering” and impart an aged look. Once you’ve distressed the trough, wrap it in plastic and leave it in a cool place to cure for about four weeks, when it will have reached maximum strength. Then it’s ready for planting.

Step 9

Start Planting

You can fill your trough with just about any growing thing. Traditionally, they’re used for rugged alpine plants, which thrive in the porous containers. Small and slow-growing, yet with beautiful flowers, alpines are well-suited for the limited confines of a trough garden. Good choices are herbaceous perennials and dwarf shrubs and conifers. The important thing when choosing plants is to consider scale and growing habits; you don’t want aggressive spreaders that will take over the trough.

The best planting mixture for alpines is organic soil with sand, grit, and small stones. A layer of gravel at the bottom of the trough is optional but will improve drainage. Before filling the trough, put a small piece of wire mesh over each drainage hole to keep it clear. And be sure to leave space in the trough for some native rocks—in addition to looking nice, they imitate the alpine environment, protecting plants from the ravages of wind and extreme temperature swings.

Speaking of temperature swings, try to keep the trough shaded in winter to limit repeated freeze/thaw cycles, which can do damage to plants and also shorten the life of the trough.