In England, there is a naturally formed volcanic rock called tufa. It was commonly used to make animal watering troughs. Over the years, it became prohibitively expensive and harder to find. So, hypertufa was invented. Hypertufa is made from Portland cement, peat moss, and vermiculite. This mixture is similar to concrete but much lighter and more porous. It also looks very similar to the traditional tufa rock.

At Renga Arts, we fabricate our hypertufa containers in custom-made forms with modern reinforcing compounds in the mix. This insures a long and stable life for our products. All of our containers are built with an internal steel frame -- they'll never break apart even if cracks do form. Every piece is hand-carved for a natural stone appearance.

It is common for concrete to form surface cracks. This is true for our containers as well -- and is not an matter of concern. In fact, we find the cracking only adds to the natural stone look. This is especially true in outdoor placements. In extreme freeze/thaw environments more severe cracking may develop. This should not be a major problem as the internal steel frame will prevent cleavage.

In the outdoors expect your container to rapidly develop patina. In moist conditions green and brown shadings form -- mostly from algae. Eventually, moss may even appear. On the lower surface of the planter, you may notice a white deposit. This is lime leaching out of the cement. If desired it can be scraped off easily.

In interior situations, the hypertufa surface should remain stable. Keep in mind that hypertufa is somewhat porous -- much like terra cotta. Never put a container directly on carpet, wood, or any other moisture sensitive surface.

The porous nature of the material is great for plants. Keep in mind that hypertufa is made with Portland cement which is rich in lime -- therefore alkaline. Over time, the pH stabilizes but can be heightened, especially in new containers. You may want to compensate your planting with acidic soil amendments for sensitive plants.