Also known as Baja ruellia, this purple-flowering shrub is hardy to 25 degrees F. and can suffer frost damage in winter, but quickly recovers in spring. It has a nicely rounded natural growth habit and should not be sheared into a formal shape. Its pruning needs are minimal when allowed enough room to grow to its mature size of 4 feet tall and 4 to 5 feet wide. Once the danger of freezing temperatures has passed, prune back to ½ their size and then allow it to grow back — no other pruning is required. Every three to four years, prune back severely to 1 foot tall and wide in early spring to rejuvenate and get rid of old, woody growth. No supplemental fertilizer is required.