Their fuzzy gray leaves and upright flower stalks suggest these two plants are related, but mullein (Verbascum thapsus) and lamb’s ear (Stachys byzantina) come from different botanical families. Lamb’s ear is in the mint, or Lamiaceae, family and has that family’s characteristic square stems. Mullein is in the Scrophulariaceae family, which includes snapdragons (Antirrhinum spp.) and foxgloves (Digitalis spp.) Both mullein and lamb’s ears are aggressive spreaders.
1. Growth Habit
Lamb’s ear forms a low carpet of silver-gray leaves over a 6-foot area. The only time this plant grows above 1 foot tall is when it shoots up fuzzy, 18-inch spikes of tiny pinkish-purple flowers. Mullein is a biennial that forms a single, basal rosette of woolly gray leaves the first year, from which it sends up a 6-foot flower stalk of yellow blooms the second year. It has a taproot and spreads mainly by reseeding, whereas lamb’s ear spreads by underground runners.
Lamb’s ear grows in U.S. Department of Agriculture plant hardiness zones 4 through 8, thriving best where summers are dry. It doesn’t tolerate high humidity. Mullein thrives in USDA zones 1 through 11. It is found in all states and most Canadian provinces, commonly growing in dry, open areas such as pastures and roadsides. It was brought to North America by early settlers who used it medicinally and made tea from the leaves.
Lamb’s ear is used as a groundcover for dry, sunny spots because it is drought-tolerant once established. In hot climates, it grows better when shaded from the afternoon sun. After planting, soak it when the soil dries out to create a deep root system. Water at the base, not from overhead, because lamb’s ear is susceptible to fungal diseases. Mullein is a sun-lover, too, so plant it in well-drained soil in full sun. It is very drought-tolerant and thrives in dry soils. It can be used as a tall punctuation point in the garden or as a meadow plant.
4. Lamb's Ear Cultivars
Improved forms of lamb’s ear and mullein are more well-behaved than the originals. Because the flower stalks can detract from the groundcover look or lamb’s ear, many people cut them off or choose varieties that rarely flower. Stachys byzantina “Helene Von Stein,” also known as “Big Ears,” has larger, thicker foliage and few flowers. “Silver Carpet” (Stachys byzantina “Silver Carpet”) is another non-flowering form with larger leaves.
5. Mullein Cultivars
Mullein is considered a weed or an invasive plant in some areas because it produces a plethora of seeds that germinate readily on open, dry ground. Cultivars and hybrids of Verbascum, however, are valuable garden plants. Verbascum “Southern Charm” reaches 3 feet tall with coral-pink blooms; it grows in USDA zones 5 through 8. Verbascum phoeniceum produces purple blooms and also thrives in USDA zones 5 through 8.
- U.S. Department of Agriculture: Classification for Kingdom Plantae Down to Family Scrophulariaceae
- Missouri Botanical Garden: Stachys Byzantina
- North Carolina State University Extension: Groundcovers: Stachys Byzantina
- Virginia Tech Department of Plant Pathology, Physiology and Weed Science: Weed Identification Guide: Common Mullein
- Washington State University Clark County Extension: Common Mullein
- Fine Gardening: Genus Verbascum (Mullein)
- Missouri Botanical Garden: Verbascum “Southern Charm”
- U.S. Department of Agriculture: Verbascum Thapsus