In 19th-century England, gardeners discovered that old water troughs carved from stone and used on farms made great planters. Unfortunately, there was a finite supply, so some people started carving planters from tufa rock, a soft, naturally occurring limestone. Then someone came up with what is called "hypertufa," a mixture of Portland cement and various additives, which can make very attractive, organic-looking planters.
Hypertufa planters are porous and lightweight, which makes them ideal for growing plants. They are easy to care for, take only a few hours to make, and an 18-by-18-inch planter costs about $4 in materials.
Most hypertufa recipes call for either perlite or vermiculite. Perlite is popped volcanic rock and does not retain water. Vermiculite is popped mica, and it does retain both water and nutrients. Both come in fine, medium or coarse powders.
Recipe 1: 1 part Portland cement, 1.5 parts perlite, 1.5 parts peat moss. Or replace perlite with vermiculite.
Recipe 2: 3 parts coconut fiber, 2 parts Portland cement, type I or II, 3 parts perlite
Recipe 3: (for heavy-duty) 2 parts cement, 2 parts perlite, 1.5 parts peat moss, 1.2 parts coarse sand plus Fibermesh. This recipe is good for stepping stones or larger items into which you want to impress decorations, such as shells, rocks or glass.
Spraying Pam or using petroleum jelly on the plastic will help a mold to release, but it also leaves grease stains that are impossible to get out.
You can find the coconut fiber and perlite at garden centers and Portland cement at construction or lumber stores. Portland cement comes only in 94-pound sacks, will not keep and becomes hard quickly, so plan to make a lot of hypertufa pots — or have a party.
Jim Clark of Wimer discovered hypertufa on the Internet and decided to try it.
"I'm semi-retired, and I just like to be doing something," he says. "It's basically just an old man playing in the mud."
Clark sells his creations at the Rogue River Sunday Market. He makes stepping stones and birdbaths as well as planters of various shapes and sizes. He makes his own molds and incorporates found items. He finds baskets make particularly attractive planters.
"Hypertufa's so organic," Clark says. "They actually support life — moss and lichens grow on them — and they patina up very pretty in about three years."
Master Gardener Katie Denton of Grants Pass has been teaching people how to make hypertufa planters for about 10 years, after she taught herself.
"I'm not an artist," Denton says, "but it looked like something to do that would be fun and inexpensive."
Her beginning class through Josephine County Master Gardeners lasts about an hour and a half, long enough to make one, basic, 18-by-18-inch project. People can bring their own molds or use one of Denton's cardboard boxes lined with plastic. "Hypertufa is a slow-setting material," Denton says, "so they can take it home and still work with it. It takes about 10 days to really dry."
Early hypertufa pots were reinforced with chicken wire, metal or rebar. Denton doesn't use them because the metal eventually makes rust stains on the pots. Coconut coir also is suggested, but Denton says it gets slimy. Instead, for added strength, she recommends using Fibermesh, a fiberglass reinforcement sold by companies that make concrete.
"I can't emphasize enough how important it is to wear safety equipment," Denton says. "Portland cement contains lime, which can burn your hands or eyes or throat, and it is really bad to inhale. As long as you wear a paint mask and safety glasses and rubber gloves, you'll be fine."
Denton says anything that can be lined with heavy plastic can be used as a mold. Small batches of Portland cement can be mixed in a wheelbarrow or 5-gallon bucket. Denton says to get Portland cement, not concrete that has additives in it. It should be a fine powder.
Start by placing all dry ingredients (see box for recipes) in a bucket and crushing all lumps, as they will not break down when wet. Add water slowly and mix. When ready, it should be the consistency of cookie dough.
Mold the wet hypertufa with your hands into a plastic-lined cardboard box or other container, making the bottom about 2 to 3 inches thick. The walls of the hypertufa container should be at least 3 inches deep. Punch two drain holes in the bottom with your finger or a tool. Clean your mixing tray with a garden hose immediately after finishing.
Smooth, carve or shape to your satisfaction using a garden trowel, wire brush or other metal tool. For a smoother finish, moisten the hypertufa and then coat the outside with dry Portland cement. You can plant in your container about a week after you make it.
Most failures occur when people try to lift the mold before it is properly cured or dried. It usually takes about 10 days indoors in winter and somewhat less time outdoors in summer. Cover the project with one sheet of newspaper and keep it moist in summer heat.
Your finished pot should last for years.
A. Paradiso is a freelance writer living in the Applegate. Reach her at firstname.lastname@example.org.