Leadwort, sometimes called plumbago, is a late summer and fall gem that is easily forgotten the rest of the year. Its green foliage is fairly nondescript until the blue flowers open on red stems in late August. The plant blooms through and beyond light frosts. Frosts only add to its interest in the garden by inducing a rich, red, leaf in the fall.
Though a fall knockout, plumbago is best planted in the spring. It spreads slowly from rhizomes that need time to get established before winter. The upright stems with woody bases grow to 18 inches. The plant is rated hardy to USDA zone 5 for Front Range gardens.
Leadwort is very shade tolerant, blooming in spots that receive only a couple hours of sunlight daily. It also thrives in full sun. Plants prosper in average soils and require only occasional watering once established.
Try planting leadwort in combination with feather reed grass, tufted hair grass, asters, buff-red flowered sedums, purple coneflower, and yellow, red or lavender-pink mums. This plant also goes well with yellow, late-summer blooming Black-eyed Susans and other sunflower relatives.
For more information, see the following Colorado State University Extension fact sheet(s).
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Updated Monday, June 15, 2015