Lewisia is a genus of flowering succulents endemic (found only in) to Western North America. Because they do best in very well-drained, low fertility soils, they are great additions to rock gardens and scree beds and can also be successfully grown in raised beds and containers. They grow best where humidity is low during the summer and require good air circulation around the plant's crown to prevent fungal disease. The blooming and growing seasons of many Lewisias is prolonged if given some afternoon shade. Although their fleshy leaves make them drought tolerant, they can be watered freely during the growing season. Those that have a dormant period should be kept drier during their dormancies.
We showcase Lewisia cotyedon and hybrids in a large mounded bed near the center of our rock garden. The mound is covered with flowers in spring, creating a living bouquet of color. Some individual plants continue to bloom throughout the hottest summer months, while most have a second bloom in the fall which can last into the winter. The mound receives occaisonal summer water but no supplemental fertilizer.
Lewisias grow on steep slopes and in vertical crevices in nature and we created our Lewisia bed by mounding a mixture of native soil, river sand and 1/4" #10 crushed rock to a height of three feet. Starting at the base of the mound, we partially buried rocks around the perimeter to stabilize the slope and create planting crevices and shelves. The plants were placed with their crowns high to ensure good air circulation. We topdressed the bed with 2-4 inches of crushed rock, working the rock mulch well under the fleshy rosettes to keep their crowns high and dry.
Lewisias in Scree Bed
Lewisia cotyledon with orange flowers at left with two Lewisia nevadensis and a Lewisia columbiana at right. Purple blooming Pasque flower (Pulsatilla vulgaris) at top right. Lewisia species grow best in low fertility environments like those found in their native habitats. These three species of Lewisia are thriving in this extremely rapidly draining, raised scree bed with no garden soil and no supplemental fertilizer. Plants can be very long-lived when grown in scree. The above Lewisia cotyledon is eight years old. This scree bed is filled with 40% 1/4" Crushed Rock, 40% River Sand, 20% Compost.
Lewisias in Containers
Lewisia tweedyi grown in a terra cotta pot.
Pink flowering Lewisia nevadensis in terra cotta pot
Many of our customers prefer to grow Lewisias in containers where growing conditions are easily controlled. Use a free draining potting mix combined with 25% grit by volume and a grit mulch to enhance drainage and air circulation. Add a small amount of time release fertilizer at planting (1/4 the regular amount) and plunge the pots in a weak liquid fertilizer solution only when plants look tired and undernourished. We prefer unglazed containers which are porous, further enhancing drainage.
We water the containers freely when plants are growing and blooming. Deciduous species such as Lewisia nevadensis, Lewisia pygmaea and Lewisia brachycalyx should be allowed to dry out after the foliage dies back. Resume watering when new growth appears. During the winter months, containers are placed under eaves or in a cool, covered space with good light and air circulation. An added advantage to providing winter protection is that it also protects the unglazed containers from repeated freezing and thawing, prolonging their lifespan.
Lewisias in Raised Beds
Lewisia columbiana (photo at left) and Lewisia cotyledon (at right) with blue flowering Globe Daisy (Globularia meridonalis)
Raised beds are typically well drained and are good places to grow Lewisias. If you need to improve drainage in your raised bed, add inorganic soil amendments such as river sand and grit or crushed rock. While our raised beds feature rocks accents, this is not a necessity in order to grow Lewisias. The raised bed needs to receive some sun each day and have well-drained, lean soil.