Verbascum bombyciferum
white felted mullein
Turkey (Bursa/Bithynia region, northwestern Turkey); rocky hillsides and disturbed ground
Overview
Verbascum bombyciferum is white felted mullein (silver mullein), a biennial. Year 1: a large silvery-white woolly basal rosette 12-18 inches (30-45 cm) tall and 18-36 inches (45-90 cm) wide of broadly elliptic leaves 12-18 inches (30-45 cm) entirely coated in thick felted silky-white wool. Year 2: a towering woolly white flower spike 60-96 inches (150-240 cm / 5-8 feet) bearing sulfur-yellow flat-faced 5-petaled flowers 1 inch (2.5 cm) in dense clusters from June through August. The species name 'bombyciferum' means 'silk-bearing' (Latin bombyx spp. + ferre spp.), referencing the silky wool. The woolly indumentum is the densest of any commonly cultivated biennial. In the figwort family (Scrophulariaceae spp.). 'Polarsommer' (syn. 'Arctic Summer') is a compact selected cultivar. RHS Award of Garden Merit. Monocarpic: dies after flowering. Self-seeds freely on bare disturbed ground — allow seedlings to establish for continuity. Lean poor soil produces the densest silver wool; rich moist soil reduces the white covering and promotes green floppy growth. Tolerates alkaline and chalky soil (pH to 8.0). Native to rocky hillsides in northwestern Turkey (Bursa/Bithynia region). Non-toxic. Deer-resistant (woolly). Drought-tolerant. Full sun. Zones 5-9. Growth rate is moderate.
Native Range
Native to northwestern Turkey (Bursa/Bithynia region), growing on rocky hillsides and disturbed ground.Suggested Uses
Planted in gravel gardens, dry borders, and cottage gardens in zones 5-9. The silvery-white woolly rosette (year 1) and the towering spike (year 2). Lean soil for dense silver wool. Self-seeds. Non-toxic. Deer-resistant.How to Identify
Appearance
Size & Dimensions
Height1' - 8'
Width/Spread1'6" - 3'
Reaches mature size in approximately 2 years
Bloom Information
Summer (June-August), lasting 8-10 weeks. Sulfur-yellow flowers 1 inch (2.5 cm) on a towering woolly spike 5-8 feet (150-240 cm). Monocarpic — dies after flowering. Self-seeds on bare ground.
Detailed Descriptions
Flower Description
Sulfur-yellow, flat-faced, 5-petaled, 1 inch (2.5 cm), in dense clusters on a towering woolly white spikeFoliage Description
Silvery-white; broadly elliptic to ovate, 12-18 inches (30-45 cm), entirely coated in thick felted silky-white wool — the densest woolly covering of any common biennialGrowing Conditions
Sun Requirements
Requires 6-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Full sun. Lean poor well-drained soil — rich soil reduces the white wool. Tolerates alkaline and chalky soil (pH to 8.0). Biennial — allow self-sowing on bare ground. 'Polarsommer' for compact form. Non-toxic. Deer-resistant. Drought-tolerant. Zones 5-9.Pruning
Leave the spike standing to self-seed (August-September). Cut the dead spike to the ground after seeds disperse. Remove the dead rosette crown. Self-sown seedlings appear the following spring.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
summerfall