Tufa - The ultimate crevice rock

Tufa is a porous limestone rock useful in growing many alpine and lime loving plants.  Not to be confused with hypertufa, a cement-based imitation used to create troughs and other lightweight containers, authentic tufa is a calcium carbonate mineral precipitate that occurs around lime rich bodies of water.  We recently obtained a supply of tufa from the headwaters of the Columbia River.  The mineral composition and general quality of tufa deposits varies and this particular deposit is quite attractive with high porosity and a golden color.

One of the most important features of tufa is its ability to absorb and hold water like a sponge. This is an advantage when plants are planted near or even in the rock where water is released slowly over time.  Plants remain evenly moist and are cooled by slow, steady evaporation.  Even on a warm day, the surface of the tufa is noticeably cool to the touch.  This prevents heat stress at the root zone of alpine plants and keeps them healthy and growing during warm weather.

The possibilities for using tufa are limited only your imagination.  Tufa can be used in troughs, in specially designed crevice gardens and also in the open rock garden. We recently created a crevice garden exclusively with tufa.  We maximized the tufa surface area by placing the rocks upright and packing them tightly together.  We then planted in the crevices and also in holes drilled directly into the rock.

Tufa can also be planted as specimen rocks.  Using a 3/8” to 1” masonry bit, holes can be drilled into the tufa and small plants can be tucked into the voids.  Over time the roots penetrate into the rock and become firmly established.  The low nutrient environment ensures the plants maintain their characteristic compact forms.

Plants suitable for use with tufa include those from limestone habitats and many others that originate in low fertility, mineral rich soils.  Acid loving plants including Ericaceous and woodland plants will not grow well and should be avoided.

 

Plants that thrive in tufa include many encrusted and cushion saxifrages, Auriculastrum primulas such as Primula marginata, P. allionii, P. auricula and hybrids, certain Campanula and Draba species as well as Ramonda and Mediterranean plants such Aethionema schistosum and Alyssum stribyrni.  We are experimenting with Western alpine plants including Telesonix, Astragalus,  Antennaria, Arenaria, Eriophyllum and Heuchera to determine their suitability for growing in and around tufa. 

We invite you to explore the possibilities for using tufa in alpine gardening.  Tufa of various sizes is now available for sale at the nursery and smaller sizes will be available soon in our mail order catalog.

For more information about working with tufa, we have posted two how-to pages on our website

• Build a Tufa Rock Garden
• How to Plant in Tufa