Yellow archangel: the devil’s in the details
Popular in ornamental gardens and hanging baskets, this invasive escapes easily and spreads quickly
Name: Yellow archangel (Lamiastrum galeobdolon)
How it spreads: Very effectively! By seeds, stem fragments and root nodes
Difficulty to remove: 9 out of 10
With silver-variegated foliage and stunning yellow flowers, gardeners might call this shade-loving perennial groundcover heavenly. Sadly, there is nothing divine about yellow archangel. In fact, it displays rather devilish behavior in the forested habitats of western Washington.
Also known as lamium, yellow archangel is popular in ornamental gardens, containers and hanging baskets. It spreads quickly, generally as a garden escapee, creating dense monocultures that allow for little else to grow. It provides poor food and shelter for native wildlife and suppresses the diversity of native plant species typically found in our forest understories.
It is highly adaptable and grows in a wide range of conditions from full shade to full sun; in sandy and heavy clay soils alike. Though it prefers moist shady sites, it’s even been found on dry sites prone to drought.
A member of the mint family, with square stems, opposite oval-shaped leaves, and whorls of yellow “hooded” flowers, yellow archangel spreads effectively by seed, stem fragments and from root nodes. Though typically a groundcover, it behaves at times vine-like, climbing and smothering understory plants as well as nurse logs. If that weren’t enough—it stinks!
What’s a decent, nature-loving garden geek to do?
Prevention is the first line of defense—avoid planting it in your ornamental gardens or near natural areas. Because yellow archangel spreads by stem cuttings, please avoid dumping your yard waste clippings in parks or natural areas or dispose of in your personal backyard compost pile. Instead, use your city’s “Clean Green” compost bin (a high heat commercial composting facility is necessary to properly kill this evil invasive).
Devil’s in the details
In order to adequately control yellow archangel, patience and attention to detail are required. Plants must be pulled up by the roots, which grow shallow but dense. This is most successful in the spring and fall when soils are moist. It is critical to sift through the soil to catch any remaining fragments. Sheet mulching with cardboard and/or burlap followed by a thick layer of arborist trips is also highly recommended.
For more information on yellow archangel identification and control or to report an infestation in your local park or natural area, contact our friends at the King County Noxious Weed program.