Erigeron compositus and Erigeron leiomerus

(Question)

I just purchased these two rock garden plants which understand prefer high altitudes.

Can you advise where I should site them – they are in appropriate soil, but how much sun can they tolerate, and what kind of moisture situations?

(Answer)

Erigeron, commonly known as ‘fleabane’, is a large genus of plants that grow in dry, mountainous and semi-desert areas of western and northeastern North America.  The flowers are “like small asters with narrower and more numerous ray flowers surrounding the yellow disk…. with trim basal foliage, usually rather grayish”. Erigerons generally have a taproot which anchors the plant  in the rocky soil and helps to protect the plant from the extremes of temperature fluctuations.  Being plants that are native to mountain areas at high altitudes, free-draining (sandy, rocky) ‘soil’ is essential – scree-like conditions would be perfect.  These plants cannot tolerate a high moisture situation.

Erigeron compositus has small white or blue flowers above silver fern-like foliage.  It is also known as the cut-leaf daisy.  It grows best in sun to part shade and even though it prefers a granite-based soil, it can tolerate a limestone soil.

Erigeron leiomerus has violet flowers on very short stems above a mat of glabrous (hairless) gray leaves.  [“Leios” is Greek for “smooth”  and “merus” means “parts”, probably referring to stem and leaves].  It is also known as Rock slide Daisy which obviously suggests that its habitat is on rocky slopes.  It will tolerate full sun to partial shade.

In general, these plants will grow in sandy, gravelly conditions, scree, alpine or rock gardens.  They will tolerate full sun and are somewhat drought-resistant.  They will withstand moisture only if the soil is well-drained.

Good luck with your erigerons; if you provide optimal growing conditions, they will reward you with many blooms for years to come.