Plant of the Month: May 2013

Purple Robe, Nierembergia scoparia

Purple Robe, aka Cup Flower, Nierembergia scoparia

Purple Robe, Cup Flower

Nierembergia scoparia


  • Plant Form: Perennial Flower
  • Water Use: Low – Moderate
  • Mature Size: 6-10 inches tall, 12 inches wide
  • Exposure: Full Sun – Part Shade
  • Bloom Time: May – October (or first frost)
  • Native to: South America
  • Hardiness: Cold Hardy to 25° F


Purple Robe forms a much-branched, spreading mound with inch-long, purple, bell-shaped flowers that literally cover the whole plant all summer. Even in heat, Purple Robe flowers hold their deep, rich color. The foliage on this long-blooming, easy-care perennial has a fern-like appearance. Trim the whole plant back after flowering to lengthen life. Plant in fall or winter for flowers in summer. Mulch in summer to retain moisture and help keep soils cool. Purple Robe is an excellent plant for rock gardens, as well as for borders, bedding, baskets, window boxes or containers. While this tender perennial normally survives our mild winters, it can be grown as an annual in areas with freezing winters.