Lamb’s Ear (Stachys byzantina) is a popular perennial groundcover cherished for its soft, velvety, silver-gray foliage. The common name derives from the appearance and texture of its leaves, which add a unique tactile element and color contrast to garden beds. It is valued in landscaping for its low-maintenance nature and its ability to form a dense mat. However, its height can be confusing because the plant has two very different vertical dimensions throughout the growing season.
Distinction Between Foliage and Flower Spikes
The maximum height of Lamb’s Ear depends entirely on whether the measurement includes the foliage mat or the temporary flower spikes. The basal rosette of leaves, which forms the groundcover, typically reaches only six to eight inches off the ground. This low, dense carpet of woolly leaves is the plant’s permanent structure and main ornamental feature for most of the year.
In early summer, mature plants send up tall, erect stems topped with small purplish-pink flowers. These flower spikes dramatically increase the plant’s height, generally reaching between 12 and 18 inches, and occasionally up to 24 inches. This temporary vertical growth represents the plant’s absolute maximum dimension. Many gardeners choose to remove these spikes to maintain the uniform, low appearance of the silver mat.
Lateral Spread and Ground Cover Growth
While the plant’s height is variable, its horizontal spread is consistent with its function as a groundcover. A single plant can spread laterally, often reaching a width of 12 to 36 inches. This vigorous spreading is achieved through creeping stems that root where they touch the soil, creating a continuous, dense mat over time.
Spacing plants 12 to 18 inches apart is recommended to allow for proper air circulation and to let the plants fill in the space quickly. This growth habit is effective for weed suppression and creating a cohesive textured effect. The dense network of stems and roots also helps to stabilize soil, making it useful in erosion control.
Environmental Factors Affecting Plant Dimensions
The ultimate size a Lamb’s Ear plant achieves is influenced significantly by its growing environment. Plants situated in full sun, receiving at least six hours of direct light daily, tend to remain shorter and produce a denser, more compact foliage mat. Conversely, plants grown in excessive shade may exhibit etiolation, stretching taller but becoming sparser and leggier.
Soil quality also plays a role in determining plant dimensions. While Lamb’s Ear tolerates poor soil, rich or overly moist soil encourages faster growth and a larger overall size. However, excessive moisture increases the plant’s susceptibility to root rot and fungal diseases. Furthermore, specific cultivars are bred for different sizes, such as ‘Silver Carpet,’ which stays short at four to six inches and rarely flowers, or ‘Big Ears,’ which features larger leaves and a potentially wider spread.
Maintenance Practices for Controlling Size
Gardeners can actively manage the plant’s vertical and horizontal growth to suit their aesthetic preferences. The most direct method for controlling the vertical dimension is deadheading, which involves removing the flower spikes entirely. Cutting these stalks back prevents the plant from reaching its full height and redirects energy back into foliage production.
To manage the plant’s lateral spread and maintain health, periodic division of the clumps is necessary. Lamb’s Ear spreads through rhizomes, so dividing the plant every few years prevents overcrowding and helps maintain proper air circulation. Additionally, removing dead or yellowing leaves in late winter or early spring helps tidy the appearance and promote fresh, tighter growth.