Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Tufa: A quick google search will define Tufa as “a highly porous, sedimentary rock (limestone) composed of calcium carbonate, CaCO3. It is formed by biological and chemical precipitation of Calcite or aragonite from cold, supersaturated surface or ground waters (springs).” You may be wondering “Why are you writing about a porous rock for this month’s tips?” Well, quite simply, tufa is the talk of the town right now in rock gardens and will soon be the featured rock of the new alpine house at Betty Ford Alpine Gardens. In fact, tufa is already being used in the rock garden. So, what is so special about tufa for alpine and rock garden plants? The first thing to know is that tufa is very porous, almost like a sponge, which can mean a few things. 1. It drains freely 2. It allows roots to grow in and around the rock. If you have ever seen alpine plants in their natural habitat in the mountains, you’ve probably seen them growing in and among rocks. This adaptation is quite hard for gardeners to duplicate on any old rock which is where tufa comes in. This delicate rock is quite light in comparison to other denser rocks of comparable size. This makes it Tufa Garden near Woodland Walkway Tufa cliff in an alpine house in Europe – Photo: Mike Kintgen easy to place and work with. Tufa is typically placed partially buried to 1/3 to ½ by soil or other growing media such as sand or peat. This technique allows the rock to absorb water and the plants to grow into the soil. Tufa can contain small to large holes that allow plants to be directly transplanted into it. If there are none, holes are also created by using a mason bit and drill. The plant is then carefully placed into the hole where it will then grow into the rock. Tufa can also be an excellent medium for plants to re-sow themselves in. Smaller tufa is often used in troughs or sometimes used as a small display piece in itself. This is for serious plant collectors and growers who want to try more difficult alpines. The tufa that the gardens will be selecting is coming from a reputable source in South Dakota. Several tons of this stone will be shipped in the spring where it will be placed inside the alpine house. It will be arranged naturally with much thought and care for design. The Tufa boulder in SD design of the bed will look “natural” like a mountain scene, and have several micro growing conditions for unusual plants such as cliffs, overhangs and shady crevices. This will provide habitat for some new, rare and difficult to grow plants. In next month’s issue I will discuss some of the plants that grow in tufa and more on the alpine house. Large tufa rock in Mike Kintgen's high elevation garden