Common Name: silver spurflower
Type: Herbaceous perennial
Family: Lamiaceae
Zone: 10 to 11
Height: 2.00 to 2.50 feet
Spread: 2.00 to 2.50 feet
Bloom Time: July to August
Bloom Description: Bluish-white
Sun: Part shade
Water: Medium
Maintenance: Medium
Suggested Use: Annual
Flower: Showy
Leaf: Colorful
Tolerate: Drought
Culture
Winter hardy to USDA Zone 10-11 where it is best grown in rich, humusy, medium moisture, well-drained soils in part shade. Plants are tolerant of heat, humidity and some soil dryness. Plants tolerate full sun in cool summer climates. In St. Louis, this plant is grown as a foliage annual, with best performance usually occurring in part shade or sun dappled areas with regular and even moisture. Avoid poorly-drained clay soils. Plants are intolerant of frost. Flower buds may be pinched as they appear when plants are grown for foliage display. It is easily propagated by cuttings. Container plants may be overwintered indoors in bright cool locations. May be grown as a houseplant.
'Silver Shield' may be grown from seed sown indoors about 4-6 weeks prior to last spring frost date.
Noteworthy Characteristics
Plectranthus argentatus, commonly called silver spurflower, is an upright-spreading, woody-based sub-shrub that is native to Australia. Although its flowers are somewhat showy, this plant is usually grown primarily for its attractive, fuzzy, gray-green foliage. As an annual foliage plant, it typically grows to 2-3' tall and to 3' wide. Ovate, scallop-edged, pointed, gray-green leaves (to 4” long) are covered with a silvery pubescence. Upright flower spikes (terminal racemes to 12" long) with tubular bluish-white flowers (each to 1/2" long) bloom in summer.
Genus name comes from the Greek words plectron meaning "spur" and anthos meaning "flower" in reference to the spur-shaped flowers of some members of the genus.
Specific epithet means silvery.
'Silver Shield' is more compact than the species. It typically grows to 24-30" tall and as wide.
Problems
Watch for mealybugs, scale and mites. Root rot and leaf spot may occur.
Uses
Primarily grown for its attractive foliage. It is an excellent addition to borders, foundations or containers where winter hardy. In St. Louis, grow as an annual for part shade summer gardens or in containers. Good in large patio pots. Interesting houseplant.