Ruellia humilis

Published On: July 2nd, 2021


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A Wisconsin prairie native, Ruellia humilis is listed in Wisconsin as an endangered species in the wild but is easily cultivated in the garden. It gets its common name “Prairie Petunia” from its pale lilac petunia-like blossoms, which are borne on sprawling stems for many weeks in summer. Another common name “Hairy Wild Petunia”, refers to the pubescent (“hairy”) leaves.

This plant is extremely hardy and tolerant of hot, dry growing conditions. As such, it is a good choice as a tallish (12”-18”) groundcover in a site where other plants might suffer. The funnel-shaped flowers are formed individually on the ends of the stems. Each flower lasts just one day and flower production isn’t profuse at any one time but the bloom season is very long-lasting for up to 8 weeks in summer.  The flowers are attractive to many native pollinators and are visited by nectar and pollen-seeking bees and butterflies as well as hummingbirds and hummingbird moths.

The pale lilac-colored flowers are highlighted by dark purple markings in the throat. Brown seedpods form as the flower ages and this plant will self-seed readily on open soil. Over time this seeding will allow the plant to colonize an area, another feature that makes it well suited for use as a groundcover.

Prairie Petunia in a Nutshell:

  • Mature height: 12”-18”
  • Mature spread: 18”-24”
  • Bloom Season: Summer
  • Light requirement: Full sun to partial shade
  • Growth form: Upright mounding habit with somewhat sprawling stems
  • Flowers: Pale lavender/violet bell-shaped flowers with dark purple markings in the throat. The flower is Petunia-like, hence the common name “Prairie Petunia”
  • USDA Hardiness Zone: Zones 4-8
  • Especially valuable as:
    • Excellent mid-height groundcover for a dry, sunny site
    • Native Wisconsin plant that attracts native pollinators
    • Good choice for native plantings, cottage gardens, rock gardens, and mass plantings

Read more about natives in Why Grow Wisconsin Native Plants?

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