Evaluation of growth, flowering, and cold hardiness of ceanothus in western Oregon.

摘要

Thirty-eight species, cultivars, and hybrid selections of ceanothus (Ceanothus spp.) were evaluated for growth, flowering, and cold hardiness in a landscape trial in Silverton, OR, from 2001 to 2005. Plants were only irrigated for establishment in Summer 2001 and were not pruned or fertilized throughout the trial. Several cultivars showed dieback and leaf damage after 22 degrees F cold events in late October and early Nov. 2002 and 2003, the most severely affected of which were Ceanothus thyrsiflorus var. griseus, C. thyrsiflorus var. griseus 'Yankee Point', Ceanothus hearstiorum, and C. thyrsiflorus 'Snowflurry'. Among the cultivars evaluated, those recommended for early bloom are 'Ray Hartman' and 'Blue Jeans'. Several cultivars are effective drought-tolerant groundcovers, including 'Wheeler Canyon', 'Joyce Coulter', and 'Joan Mirov'. Among the smaller-growing plants, Ceanothus cuneatus var. rigidus 'Snowball' and Ceanothus gloriosus 'Heart's Desire' made effective groundcovers only 0.6 and 0.2 m tall, respectively.