Cassiope mertensiana is native to sub-alpine to alpine tundra of western North America, from Alaska south to California. It forms a low sub-shrub with dark green, evergreen, scaly leaves arranged in four rows along the stems. Plants reach about 10-20 cm tall but can form mats 30 cm or more across. Flowers are solitary from the upper leaf axils. They are 6-8 mm long, nodding and bell-shaped with white corolla and reddish calyx. In the wild, it generally flowers June through July.
June to July in the wild but as early as May in southern growing regions.
This species requires acidic, organic-rich soil that is free draining so the addition of grit is suggested. The growing site should be cool but in full sun if possible. Hardy in zones 5-7 but dislikes hot, humid weather and performs best with even snow-cover. Placing an evergreen bough over the plants in late autumn can help them better cope with irregular snow-cover.
Primarily by cuttings. Tip cuttings are taken in late summer to early fall, rooted in a shaded frame or under mist. Seeds may be directly sown on a peat-sand mix but germination may be prolonged and the growth of seedlings is quite slow.