Clay phacelia has blue to violet flowers and stands 4-14 inches (1-3.6 decimeters (dm)) tall. Germination occurs in late summer and early autumn, and basal rosettes form in October. Clay phacelia was formerly considered a winter annual but new data supports the idea that Clay phacelia is instead a true biennial (Meyer 2011). The life history of a biennial includes seedling emergence in the spring, growth of a rosette in the summer, vernalization during the following winter, and flowering, seed set, and death the second summer (Meyer 2011).