Verbascum or mullein is a biennial or short-lived perennial that is native to Africa, Asia and Europe. According to the USDA, European settlers introduced the seeds of the common mullein (Verbascum thapsis) to America and used them in a crushed form to poison fish for an easy catch. The common mullein is a biennial and has gray foliage and yellow flower spikes that tower over other plants. Cultivated varieties fit a more ornamental niche in the garden and often self-seed to offset their short life span.
Due to its weedy reputation, its height and a lack of commercial availability, the common mullein rarely has a place in the garden. If you like the look of the common mullein's yellow candelabra despite the plant's negative aspects, you can obtain this verbascum by collecting seeds. Most gardeners prefer to plant the shorter, more genteel hybrids such as the grenadine-colored Caribbean Crush and the purple Sugar Plum.
Culture and Care
Verbascums prefer full sun and require excellent drainage as the entire plant will quickly rot from too much moisture. In addition to the drainage, the soil should have average fertility. Verbascums will grow too tall in a rich soil and will fall over. Deadheading the spent flowers of the cultivated varieties will prolong the blooming period and also lengthen a plant's lifespan. The flowers are numerous and the bloom time last several weeks starting in spring. Verbascums are hardy to USDA zones 5 to 8.
Plant the seeds of the common mullein by scattering them on bare soil. Basal foliage appears the first year, followed the next year by the flower spikes. Other verbascums are raised from seed or from plants in nursery containers. Verbascum Southern Charm is an excellent candidate for growing by seed and often flowers the first year. Potted verbascums grow more quickly, and these hybrids offer more color choices. Dig holes twice as wide as the pot and 8 inches deeper, backfill the soil around the plant and water it thoroughly. Do not plant verbascums too deep or overwater the plants.
According to a Fine Gardening's online plant guide, verbascum species will grow well in rock gardens or in dry areas where they can naturalize. Cultivated varieties are a good match for mixed borders or cottage gardens. Verbascum Sugar Plum grows only 15 inches tall and works well in a container.
The National Park Service estimates that the seeds of the common mullein may number 180,000 from a single plant and may be viable for 100 years. Cultivated varieties are not so prolific. Leave the flower stalks on these varieties to encourage seeding. Be aware that seedlings will not be true to the parent plant. Another means of propagation is by root cuttings.This process involves lifting the plant when it's dormant, cutting pieces of the roots and placing them sideways in a planting medium.They will eventually sprout a new plant.
The common mullein is considered "a noxious weed" by the USDA. When deciding whether to sow the seeds of this verbascum in your garden, take into account the plant's invasive nature and dispose of all but a few of the flower spikes.
Verbascums are problem-free, except for hosting caterpillars and spider mites in the hot weather. Powdery mildew and leaf spot can also occur.