Volcanic sorrel Oxalis vulcanicola 'Zinfandel' Photo/Illustration: Bill Johnson 1 2 3 4 5 6 7 8 9 10 11 Volcanic sorrel (Oxalis vulcanicola 'Zinfandel') oks-AL-iss vul-kan-IK-oh-lah Genus: Oxalis The old-fashioned shamrock houseplant is now high fashion. Several introductions from Proven Winners push this group to the fore for its elegant foliage; abundant, delicate flowers; and vigor. Only 6 to 10 inches high with a spread to 12 inches, this plant’s tiny, ¾-inch-wide, bronze-colored leaf clusters and bright yellow flowers are massed on trailing stems that spill over the sides of shaded window boxes and containers. Noteworthy Characteristics: Nice houseplant. Care: Though this shamrock is frost tender, it is easy to overwinter indoors. Propagation: Sow fresh seed or divide rhizomes. Problems: Fungal leaf spots, powdery mildew, rust, and seed smut are the most common problems, but also watch for spider mites and leaf miners. Overview Height 6 in. to 12 in. Spread 1 ft. to 3 ft. Growth Habit Clumps Growth Pace Moderate Grower Light Full Sun Only Moisture Medium Moisture Maintenance Low Characteristics Showy Foliage Bloom Time Early Spring, Early Summer, Late Spring, Late Summer, Spring, Summer Flower Color Primrose Yellow Foliage Color Colorful/Burgundy Foliage Uses Beds and Borders, Container, Ground Covers Style Cottage Garden, Woodland Garden Seasonal Interest Summer Interest Type Perennials Oxalis vulcanicola 'Zinfandel'View the discussion thread.