The Purple Haze of Lamium

The “purple haze” across lawns and roadsides right now is unrelated to Jimi Hendrix. Instead, it is either Purple Deadnettle or Henbit or both. These weeds are common in the southeast, and can be found growing together. They spread readily and plague homeowners who want a pristine lawn. As a child, I loved the purple flowers with tiny freckles, and gathered many a tiny bouquet as a gift to my tolerant mother.  

A close look reveals the differences between the two. Purple Deadnettle (Lamium purpureum) has heart-shaped leaves, slightly hairy, that attach to the stem with a stalk. The topmost leaves have a purple cast.  Henbit (Lamium amplexicaule) has rounded leaves with scalloped edges that wrap around the stem. Leaves are uniformly green, and attach directly to the stem without a stalk. Stems are square for both, indicating they are members of the mint family. 

These two weeds are not native, but a Eurasian import that has made itself right at home here in the US. While I pull them from my flower beds and borders, I leave those in lawn areas alone.  Deadnettle prefers more sun than Henbit, which prefers shade to partial shade. They appear in all soil types.

Deadnettle and Henbit are reported to be edible. (In this case “edible” means non-toxic and does not equate to “palatable.”) Chickens enjoy eating both flowers and foliage. The blooms provide nectar to honeybees when few other flowers are available, and are also popular with hummingbirds, although peak Henbit season is past when our first hummingbirds appear here in upstate South Carolina. Both plants work well to control erosion (yay!) but set thousands of seeds, all of which seem to germinate (boo!). They can overtake a lawn. 

Both prefer cool temperatures of late winter and early spring, and will gradually fade away once weather is consistently warm. Both plants are annual, so don’t waste time and money applying herbicides.  If you don’t want them in your garden next year, apply anti-emergents in late summer or early fall when dormant seeds are starting to germinate. If you simply must rid yourself of these plants, use an herbicide labeled for broad-leaf weeds and follow the application instructions exactly.

Henbit

Purple Deadnettle

Weed of the Week: Bittercress

While most other plants are just awakening from winter hibernation, Bittercress (Cardamine hirsuta) is actively growing and blooming.  It is an annual weed in the mustard family. It reseeds itself so rapidly that it appears to be perennial. The plant forms a basal rosette of lobed leaves and sends up a wiry stalk. The 4-petal white flowers have a lavender tint near the base. The flowers can mature and set seed in less than a week. Once a few plants have seeded, it is almost impossible to eradicate from the lawn or flower beds.

Pulling the weeds while they are small, before they set seed, is the best way to control this invasive demon. They are easy to remove when soil is damp. If you allow them to seed, you will need to employ both pre-emergent and post-emergent herbicides (look for product that controls broadleaf weeds) to tame it.

Even a tiny plant can bloom. See the photo below, with a house key to show size of the blooming plant. The seed pods, called siliques, look like purple toothpicks. The pods will explode at the slightest touch, throwing seed up to 15 feet away from the mother plant. One of its common names is Shotweed. There is a term for this ballistic seed distribution system: ballochory. Touch-me-nots (Impatiens balsamina) also throw their seeds around this way.

In a Master Gardener class I attended some years ago, the instructor showed a photograph of a nursery in which one Bittercress was left alone for nine weeks. It went from a single plant to an entire village. That one plant spread its progeny to the surrounding twenty-four flats of plants — in just nine weeks!

Bittercress leaves are edible. I’m told they taste like arugula. They do support several varieties of butterflies and one obscure bee, but they are also favored by aphids. In the Mary Snoddy garden, this means “Off with their heads!”

Weed early and weed often.

A single, tiny bloom produces a bazillion seeds, all of which will germinate.