A simple mixture of peat moss, perlite, Portland cement and water — and a dose of creativity — are all that’s needed to fashion artful garden containers that resemble weathered stone.

Hypertufa, as the material is known, was concocted as a lightweight substitute for a natural limestone rock called tufa. It was first used in the 1930s to replicate the stone troughs popular among English gardeners in the late 19th and early 20th centuries, according to DIY doyen Martha Stewart’s website.

You don’t need to be Martha Stewart to make your own hypertufa planters. Diane Moses, community relations specialist at the Honolulu Board of Water Supply, conducts classes at the Halawa Xeriscape Garden on how to make the containers. She said she saves plastic food containers to use as molds. Ice cream tubs, tofu packs, poke bowls — almost anything will do.

“It’s a great way to recycle the containers,” she said. “You can even use the triangle sandwich container for a mold. That’s the fun part, finding all of the different ones to use.” Shallow containers are good for succulents, while deeper pots can be used for other plants, like bromeliads, she added.

The inexpensive ingredients for this beginner-level project are readily available at garden and variety stores. Perlite, a volcanic glass added to potting media for aeration, provides a sandy finish. For a smoother surface, Moses said to substitute vermiculite, a similar soil additive.

A handful of fibermesh, used in masonry work, can be thrown in to strengthen the mixture.

In her classes, Moses uses a method in which hypertufa is sandwiched between two molds. Another method involves packing the material around an overturned plastic bowl or pot. River rocks, gravel, leaves and other objects can be pressed into the surface for added interest, or, once the hypertufa has partially set but is still damp, designs can be carved into it.

Moses stressed the importance of wearing garden gloves covered with plastic gloves when mixing hypertufa because of the caustic nature of the materials. For that same reason a dust mask is advised.

Make sure the molds are ready before the ingredients are mixed. Moses said there’s about a 20-minute window to work with hypertufa before is it starts to harden.

Like any cement product, your planter will need to cure. Moses advises flushing it with water over the course of six weeks to reduce the alkalinity from the lime in the cement, which is toxic to plants.

The same process can be used to make steppingstones and other forms.

Moses will lead her next Hypertufa Planter Workshop on May 7 from 10:30 a.m. to noon. Cost is $15.

INSTRUCTIONS

>> Step 1: Slowly mix 1-1/2 parts each of peat moss and perlite with 1 part Portland cement. Add fibermesh for strength if desired. Add water in increments, mixing each time, until attaining the consistency of cottage cheese.

>> Step 2: Cover outer mold with plastic wrap. Place hypertufa mixture over plastic wrap, about 1/2-inch thick. Pat down to remove air pockets and push into corners. Pack the sides, about a 1/2-inch to 1-inch thick. Insert a smaller container and fill gaps between molds. Gently tap outer mold with mallet to remove air bubbles. If desired, embellish the edges with rocks, aquarium gravel or other materials.

>> Step 3: Use wooden dowel or stick to poke a drainage hole through the molds, and leave dowel in place. (If preferred, a hole can be drilled once pot has dried.) Place pot in a plastic trash or shopping bag in shady place for up to 48 hours.

>> Step 4: Unwrap and gently remove molds and dowel. Smooth edges with wire brush.

>> Step 5: Rewrap pot and place in shade for another two days. Unwrap and flush with water periodically over six weeks to reduce alkalinity before adding plants.

Makes 4 small pots.

The Halawa Xeriscape Garden is at 99-1268 Iwaena St. Visit bit.ly/1MuVI8W for a list of classes.