Redwood sorrel, Oxalis oregana, gets that common name because it grows prolifically under the giant redwoods in northern California. But you don’t have to have redwoods to grow this attractive groundcover. Other common names for this plant are wood sorrel and Oregon oxalis. In the wild its also common in the understory of low-elevation Douglas-fir forests. It is native from British Columbia to California.
Like most groundcovers, redwood sorrel spreads rapidly from underground rhizomes and forms a dense mass. It’s easy to establish in the shade garden by dividing and transplanting pieces of an existing plant. Give it a good organic soil and moderate moisture in a shady spot. In 2-3 years you’ll have a delightful green carpet. Once established it is fairly drought tolerant.
Redwood sorrel blooms sporadically in my experience, usually with just a few blooms scattered about. The flowers, generally white with red lines, can appear any time from spring through early fall. While I like the flowers, this is really a wonderful foliage plant with large clover-like leaves.
Grow redwood sorrel in full or part shade. The leaves are very efficient photosynthesizers. When they’re struck by too much sunlight they’ll fold down as a protective measure, then return to their usual horizontal orientation when shade returns.
In our old garden we had redwood sorrel growing under our rhododendrons. In our new garden I’ve planted it in the shady border next to our driveway, under a variety of shrubs and vines. I think it’s particularly nice along a path, or mixed with ferns and trilliums.