This is a species of concern in Montana, known only from a small population in the NW part of the state. Our plants originally came from divisions from a captive population; no wild plants were disturbed! The species is threatened by development of its prairie habitat and also invasive weeds.
 
It turns out, however, that columbian onion is a great garden plant, with thick succulent evergreen leaves and globe-shaped flowers that bloom very late for a native onion (August!). The flowers are pale to deep pink and are a bumblebee favorite. It grows in a well-behaved compact clump that can be divided in the spring or fall.
 
This species likes full sun. While it doesn't need much water, it will bloom more profusely with a little extra irrigation (just make sure the soil is well draining). In its natural habitat it inhabits swales where extra moisture collects, especially in the spring.