Members of the Lewisia genus are small hardy perennials. They have rosette leaves that carry stiff stems.
Atop of these stems Lewisia has cup shaped flowers of white, pink, purple or red; these come into bloom from spring through to the first months of summer.
One of the common names for Lewisia is Bitterroot.
Lewisia rediviva - Bitterroot by Brewbooks.
Common Names: Bitterroot, Lewisia: Cantelow’s; Shortsepal; Columbian
Life Cycle: Hardy perennial.
Height: 2 to 12 inches (5 to 30 cm).
Native: Northern America.
Growing Region: Zones 4 to 8.
Bitteroot can be grown from seeds outdoors by sowing fresh ripe seeds on the surface when available (late autumn/ early winter). They can grow in either sunny or lightly shaded areas of the garden that have a rich, gritty and moist soil. Ideally the pH that Bitterroot grows in will be of pH 5 to 8.
If you first plan to start Bitteroot off indoors, be aware that they are quite hard to grow. The seeds should be first imbibed by placing the seeds (within soil) in a black plastic bag, then placing in the fridge for five weeks. Seeds should then be sown out at a temperature of 10 to 15 degrees Celsius (50 to 59°F). They can take anything from one to two years to germinate. They should be allowed to grow for a further year before transplanting outside.
Small species of Lewisia should be spaced at about 5 cm (2 inches) apart and larger ones up to 20 cm (8 inches) apart. If you require more Lewisia then plant the aerial rosettes that the plant produces in the summer; this is much easier than growing bitterroot from seed.
Once growing Bitterroot and other Lewisia are quite difficult to look after. Plants are susceptible to crown rot, so set the crowns about 3 cm (1 inch) above the soil, and fill the gap between the crown and soil with stone chippings.
It is important to protect the Lewisia plants from overhead water, so try to grow under a crag in the rock garden. Additionally it is important to make sure that they have an adequate supply of water, so water from below to keep the soil around Lewisia moist.