Hypertufa and Native Plants

HYPERTUFA AND NATIVE PLANTS

By
Frank W. Porter
Porterbrook Native Plants

Native plants grow in every conceivable type of habitat. From the lowest meadow to the top of the mountains, native plants have adapted successfully to dry shale barrens, acidic bogs, swamps, prairies and deeply shaded woods. Most gardeners do not have this type of diversity in their landscape. Constructing hypertufa containers is one way to grow native plants from these diverse ecosystems.

Originally, these types of containers were made from tufa rock. Tufa is a soft, friable and porous calcite rock that forms by precipitation from evaporating spring and river water. Because of its light weight and porosity, these containers were perfectly suited to grow alpine plants. Unfortunately, tufa became quite scarce and expensive due to excessive collecting.

Hypertufa is a handmade stone. It is simply a combination of cement, peat moss and sand which can be molded to create garden containers. Originally developed as a way to grow difficult alpine plants from around the world by providing the unique growing conditions that these species required, hypertufa offers native plant gardeners a similar means to create the necessary environment of many temperamental native plants. Also, hypertufa containers allow gardeners without a lot of garden space to grow several native plants in a smaller area.

Constructing a hypertufa container is an entertaining way to spend a rainy afternoon. The first step is to select the mold in which you will shape your container. Discarded metal or rubber dishpans and hospital bedpans make excellent molds. The three basic ingredients are portland cement, mason’s sand, and milled peat moss. To create a porous texture like tufa mix one part portland cement, one part mason’s sand, and two parts milled peat moss. You want your mix to be the consistency of bread dough—not too wet and not too dry.

To begin making your hypertufa container, cover your molds with a thin sheet of plastic. You can use plastic garbage bags or supermarket bags. Make sure the entire surface of the mold is covered in order to prevent the mixture from sticking to the sides. Begin filling the bottom of the mold to a depth of one and a half inches. Press the mixture firmly to eliminate any air holes or pockets. After creating a drain hole in the bottom, you can start building the walls making them two inches thick and being sure that you have packed the mixture tightly against the mold.

After you have achieved the desired shape, set the container aside and allow it to dry for forty-eight hours. Once the container is dry enough to handle, gently remove it from the mold. Be sure that all of the plastic has been removed from the surface of the container. To give it a weathered appearance take a wire brush and carefully distress the surface to remove any sheen left from the plastic and also to make sure that any thin edges or protuberances are eliminated. You can also use a gouge or chisel to create signs that the container was sculpted from solid stone.

Set the container aside in a shaded spot and let it finish curing for five weeks. Before planting anything in the hypertufa container, you must thoroughly rinse it to remove any traces of the chemicals released in the cement.

The soil mixture for your hypertufa container consists of screened leaf mold, peat moss, coarse sand, and finely shredded pine bark. To ensure good drainage, place a one-half inch layer of gravel in the bottom of the container. You should also use either turkey grit or small pebbles as mulch around your plants. This will help prevent the soil mixture from drying out.

What can you plant in your hypertufa container? One thing I have done with my smaller containers is to plant individual species, especially ones that are difficult to sustain in a garden situation. Draba ramosissima (Rock Twist) is a beautiful plant that grows on shale barrens. It is truly one of our alpine species from the Allegheny Mountains, and is not well-known among native plant enthusiasts. From a four-inch bun of tight foliage, it produces sprays of tiny white flowers that resemble Gypsy’s Breath. Quite often, the seeds will fall into the soil mixture and produce seedlings the next year.

Native sedums are also excellent choices. Sedum ternatum, with its dark green foliage and bright white flowers, will fill a container and droop nicely over its sides in a shaded spot. Sedum glaucophyllum, which has a lighter green foliage and cream-colored flowers, will perform similarly but can take a little more sun. And Sedum telephioides, with its glaucous leaves and pink starry flowers, will reach a foot in height.

If you construct a container that is a minimum of one foot by two foot in size, you can create a small habitat for several different species. One example would be to plant Aster linarifolius (Stiff Aster) in the center of the container. Its foliage resembles Rosemary, and its blue petals and yellow corona will be a welcome sight in early fall. On one corner, you could plant Campanula rotundifolia (Harebell). Its delicate and dark purple flowers bloom in early summer. On the opposite corner, you can use Antennaria virginica (Shale-barren Pussytoes) with its silvery rosettes of fuzzy leaves. Iris verna (Dwarf Iris) can be planted at another corner. Its purple flowers appear in early spring. And finally Meehania cordata (Meehania), with its one-inch pale blue flowers, could be placed at the last corner and allowed to spread over the sides of the container.

Growing native plants in hypertufa containers will become a new and fascinating gardening experience. You will be able to enjoy the beauty of plants that grow in diverse habitats and are not often seen by gardeners. Your choices of what species to grow is limited only by your enthusiasm and the size of your hypertufa container.

Reprinted with permission from the Marietta Register