This simple 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 carefully filled with sifted, sandy loam. The purpose of this arrangement was to afford sharp drainage to the crowns of the plants while allowing the roots to colonize the moist earth behind the wall. The north-facing vertical aspect is a haven for plants that require bright light but would suffer from direct sun. A surprising number of plants thrive under these conditions.
After twenty five years, many of the original Saxifraga, Campanula and Androsace that were teased into the crevices have continued to thrive and many other plants have seeded and spored in as well. These include a few delightful surprises such as Dicentra eximia, Asarum europeum, Athyrium niponicum var. pictum, Polystichum braunii, Asplenium tricomanes and Adiantum pedatum. As the result of selective weeding, the wall has become primarily a fern garden.