Rough, Tough Planters

If you’re overwintering herbs in containers outdoors, you want your hardy plants to be in hardy pots. For those of us who live in areas where winters are harsh, options narrow for plants that will survive outside; so, too, do choices for containers. Terra-cotta often crumbles by spring, and ceramic containers may crack during freezes. Plastic is generally winter hardy, but it may not suit your sense of garden aesthetics. Whiskey barrels work well, but they may be too big and too heavy to move around. If you’re like me, you make do with what you’ve got, but you’re probably on the lookout for alternative ideas for inexpensive outdoor containers.

While visiting Ithaca, New York, last summer, I saw some stalwart plant containers that intrigued me. They looked like stone, rugged and sturdy. They were fashioned in varying sizes and sometimes unusual shapes, from troughs to flaring bowls. They had an odd and rustic charm, and they fit easily and naturally into garden settings. I was told these containers were home-made, constructed from hypertufa—a mixture of portland cement, peat moss, and vermiculite.

When I got home, I had to try my hand at it, and I soon realized that these simple containers have many virtues to recommend them beyond their homemade charm. They’re easy, prac­tical, inexpensive to make in quantity, and because they’re porous, they drain well. You can make them in sizes and shapes to suit your needs, and they are lighter in weight than they look. They’re fun to make, children enjoy helping, and it can be a good project for winter months if you have an area such as a basement where you don’t mind a little mess. Sometimes the finished product is less than elegant, but the style suits me: I’m more interested in tough and enduring containers than in gracious statements. They will last for many years.

The stony texture of hypertufa is pleasing and appropriate for herb plantings and rock gardens. Creeping thymes, for example, will scramble happily over the sides. Soft green or gray foliage and gaily colored flowers are offset beautifully by the rough texture.

The containers age well and take on a weathered look. Should they break or crack (not likely if you reinforce them when you make them), you can patch them with more hypertufa so effectively that the damage is barely noticeable.

Barbara and Robert Cotts have made many of these pots, and they regularly conduct classes on the technique at Cornell Plantations, the arboretum and botanical gardens at Cornell University. They first saw these handcrafted hypertufa containers in 1986 in England, where they are very popular, Barbara says. Traditionally, the hypertufa is shaped into rectangular troughs 2 to 4 feet long. When the Cottses were last in England in 1993, they noticed them in gardens everywhere.

There are many recipes for hyper­tufa. Varying the ratio of ingredients results in varying textures, as does substituting fine-textured masons’ sand for the vermiculite. Some people add strengtheners or colorants, and there are any number of techniques for shaping the pots. I asked Barbara to coach me through my first attempt at making a container, as she has tried many variations.