40 days. (Claytonia perfoliata) Annual, reseeds easily USDA zones 6 and warmer. A native wild plant, it makes a delicate, refined salad green rich in vitamin C. This exceptionally easy to grow annual has become a mainstay of market farmers and home gardeners, as it is a cold-hardy, cut- and-come-again green to grow in spring, winter and fall. Samples of wild claytonia were collected in 1735 by botanist John Clayton. The common name miner’s lettuce is a reference to the prospectors in the 1800s California gold rush who would forage this common wild green to fend off scurvy. This light and refreshing green will grow in a variety of soils and thrives in cool and cold weather. It is commonly grown throughout winter in fairly mild climates and can grow over winter in the north with just a bit of protection. It is a supreme choice for temperate and northern permaculture design as it makes a carefree and nutritious edible ground cover, returning each season from dropped seeds.