Wall Gardens

Tufa is a naturally occurring, precipitated rock comprised of nearly pure calcium carbonate. It is light weight, porous and is easily colonized by the roots of lime-loving plants. In a traditional rock garden, the plants are grown between the rocks. In a tufa garden, the plants are grown in holes bored into the rock. Alpine plants established in tufa grow very slowly and are as thrifty and compact as they would be in a natural limestone outcropping. The feeling of the tufa garden is at once sparse and charming.

An article by Don Avery entitled “Growing Lime-Loving Ferns in Tufa in Vermont” appeared in the spring 2009 edition of the “Hardy Fern Foundation Quarterly.” To see the full text of that article click here.

Salix reticulata, dwarf form from Newfoundland

Sagifraga ‘Your Success’

Portion of tufa wall built in 2003

Saxifraga oppisitifolia has begun to seed into the tufa

Ferns growing in north-facing tufa rock

Dryopteris fragrans not strictly lime-loving

Cryptogramma stellerii: sterile fronds in the below,

fertile fronds above

Asplenium scolopendrium: American Hart’s Tongue Fern

This north-facing retaining wall was built in 1986 with the idea of growing rock-loving plants in the sharply drained crevices. The stones were laid up and shimmed in the traditional manner, but the spaces between the stones were then filled with sandy loam. This allows the plants to extend their root-run into the moist earth behind the wall. The north-facing vertical aspect affords sharp drainage for the crowns of the plants and is a haven for plants that require bright light but would suffer from direct, hot sun.

After twenty years, many of the original Saxifraga, Campanula and Androsace have continued to thrive and many other pants have seeded and spored into the crevices. These include a few pleasant surprises such as Dicentra eximia, Asarum europeum, Athyrium niponicum var. pictum, Polystichum braunii, Asplenium tricomanes and Adiantum pedatum.

THE WALL GARDEN

Asplenium tricomanes