This is one in a weekly series featuring the UC Davis Community Favorites, 75 can't-fail, easy-care plants well-adapted to our region and recommended by local gardeners.
Size: Under 3 feet tall
Bloom season: Late spring, summer, early fall
Exposure: Full sun to partial shade
Pruning needs: Can be aggressive grower; cut stems back to keep compact
Water needs: Once established, water deeply once a week
Snapshot: This pretty evergreen perennial offers abundant deep blue-purple flowers from spring well into fall. Each tubular bloom lasts only a day, but this plant is rarely out of flower to the delight of butterflies. In Sacramento, it thrives in partial shade and well-drained soil. Eye-catching in borders or beds, ruellia also grows well in containers. Its one drawback: It reseeds easily and can grow aggressively. You can see specimens in the shade of the arboretum's conifer collection on the UC Davis campus.
Why it's a Favorite: "Tall vertical structure, with deep green leaves, maroon stems, and purple petunia-like blooms that last just one day," said Margaret Kralovec, the arboretum's community outreach manager. "Makes a striking impression in a close grouping."
Read more about the Arboretum's 75th anniversary at http://arboretum75th.ucdavis.edu. For more on the Community Favorites and Arboretum All-Stars, click on http://arboretum.ucdavis.edu. Don't miss the arboretum's first public sale of the fall, 11 a.m. to 1 p.m. next Saturday at the arboretum teaching nursery.
See a photo gallery of the Community Favorites online at www.sacbee.com/home_garden.