What is Tufa?
Lime tolerant plants can be grown in and around tufa, a porous calcium carbonate-based rock prized by alpine enthusiasts. In this low nutrient environment, alpines are slow growing and maintain a tight, compact form. Water sensitive plants can be inserted vertically into the rock or even under overhangs where they are shielded from the elements.
At the same time that tufa helps alpines avoid excessive moisture on the foliage and crown, the tufa itself absorbs and holds water like a sponge. Water is released slowly over time allowing plants to remain evenly moist and cooled by the slow, steady evaporation and preventing heat stress at the root zone.