What Is Purple Deadnettle?

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Purple deadnettle (Lamium purpureum), a member of the mint family (Lamiaceae), is a common annual weed found in gardens, lawns, and agricultural fields. Often mistaken for its close relative, henbit (Lamium amplexicaule), purple deadnettle can become a nuisance if not correctly managed. This article provides a comprehensive overview of purple deadnettle, detailing how to identify it, how it differs from henbit, its life cycle, and effective management and control strategies. Reach out to the experts here at Blue Sky Landscaping after reading for more information on combating lawn weeds in Virginia!

Identifying Purple Deadnettle

Purple deadnettle is easily recognizable by several key characteristics:

Leaves

  • Shape and Arrangement: The leaves are triangular to heart-shaped, with prominent veins and a serrated margin. They are arranged oppositely on the stem.
  • Color and Texture: Young leaves at the top of the plant are often purplish, especially in cooler weather, while lower leaves are green. The leaves are covered in fine hairs, giving them a slightly fuzzy texture.

Stems

  • Structure: The stems are square in cross-section, a common trait in the mint family.
  • Growth Habit: Purple deadnettle grows upright, reaching heights of 4 to 12 inches.

Flowers

  • Color and Shape: The pink to purple and tubular flowers emerge from the upper leaf axils in clusters.
  • Blooming Period: It typically blooms in early spring, but in mild climates, it can flower throughout the year.

Differences Between Purple Deadnettle & Henbit

Example of henbit.
Example of purple deadnettle.

Though similar in appearance, purple deadnettle and henbit have distinct differences:

Leaves

  • Purple Deadnettle: Leaves are triangular to heart-shaped with petioles (leaf stalks) on the lower leaves. The upper leaves are more densely packed and have a purplish tint.
  • Henbit: The leaves are rounded with scalloped edges and sessile (without stalks), wrapping directly around the stem.

Growth Habit

  • Purple Deadnettle: Generally more compact with a denser cluster of upper leaves.
  • Henbit: Typically more sprawling and open, with leaves spaced further apart along the stem.

Flower Arrangement

  • Purple Deadnettle: Flowers are clustered at the top of the plant.
  • Henbit: Flowers are more spaced out, arising from the axils of the upper leaves.

Life Cycle Of Purple Deadnettle

Understanding the life cycle of purple deadnettle is crucial for effective management. Here is an overview of its annual life cycle:

Germination

  • Timing: Seeds germinate in late summer to early fall, although some germination can occur in spring.
  • Conditions: Germination is triggered by cooler temperatures and sufficient moisture.

Seedling Stage

  • Development: Seedlings develop rapidly, forming a basal rosette of leaves that helps the plant survive winter conditions.

Vegetative Growth

  • Early Spring: With the onset of warmer temperatures, purple deadnettle transitions to rapid vegetative growth, producing upright stems and additional leaves.

Flowering & Seed Production

  • Bloom Period: Flowers emerge in early spring, continuing for several weeks.
  • Seed Development: After pollination, seeds develop and mature, ready for dispersal by late spring to early summer.

Seed Dispersal

  • Mechanism: Seeds are dispersed primarily by wind and water, as well as through human activities such as soil movement and machinery.

Controlling Purple Deadnettle

Effective management of purple deadnettle involves a combination of cultural, mechanical, and chemical methods:

Cultural Control

  • Proper Lawn and Garden Maintenance: Maintain dense and healthy turf through regular mowing, fertilization, and irrigation to minimize bare soil areas where weeds can establish.
  • Crop Rotation: In agricultural settings, rotating crops and maintaining cover crops can reduce the prevalence of purple deadnettle by disrupting its life cycle.

Mechanical Control

  • Hand Weeding: Hand-pulling can be effective for small infestations, especially when the soil is moist. Ensure the entire root system is removed to prevent regrowth.
  • Mulching: Apply a thick layer of mulch in garden beds to suppress weed growth by blocking light and inhibiting seedling emergence.

Chemical Control

  • Pre-emergent Herbicides: These can prevent seed germination if applied in late summer to early fall before germination begins.
  • Post-emergent Herbicides: Selective broadleaf herbicides can control established purple deadnettle plants. Application is most effective when plants are young and actively growing in early spring.

Management Of Purple Deadnettle

Combining cultural, mechanical, and chemical methods can effectively control purple deadnettle. Regular monitoring and early intervention are key components of a successful management approach, ensuring long-term suppression of this resilient weed.

Purple deadnettle, with its distinctive appearance and invasive nature, can be a challenging weed to manage. By understanding its identification characteristics, differences from similar species like henbit, life cycle, and employing a combination of management strategies, gardeners and landscapers can effectively control and prevent the spread of purple deadnettle. Combining cultural, mechanical, and chemical controls, an integrated approach will ensure the best chance of maintaining a healthy, weed-free environment.