Winter Weeding: Hairy Bittercress

Cardamine hirsuta
Hairy Bittercress
By Emma Erler, The Alice and J. Liddon Pennock, Jr. Endowed Horticulture Intern

This time of year there isn’t too much happening in the garden. Most plants have gone dormant for the winter. However, as the snow melts you may notice a low growing plant with a basal rosette of leaves. This is a common weed in the mustard family called hairy bittercress (Cardamine hirsuta).  Hairy bittercress is a winter annual, which means its seeds usually germinate in cool, moist weather. Seedlings emerge mainly in late summer or fall. They are frost hardy and will remain dormant through the winter until temperatures warm up. In early to mid-spring, hairy bittercress will resume growth, produce flowers, and go to seed. Plants die back as soon as hot weather arrives in late spring and summer.
As a seedling, hairy bittercress has simple kidney-shaped leaves. Mature plants have prominent basal rosettes of hairy, compound leaves with shallowly lobed kidney-shaped leaflets. Flowering stems emerge from the rosette and have only a few small leaves. Hairy bittercress flowers are very small (2-3 mm) in diameter with four white petals. The subsequent fruits are 1-2 cm long capsules that explosively disperse their seeds up to 3 meters from the plant.

The best way to control hairy bittercress in the garden is to remove it before it sets seed. Each plant is capable of producing many thousands of seeds, hence removing the plants before seeds are set will greatly control the population. Small populations can be easily hand pulled from the garden. In large areas, regular hoeing will prevent plants from flowering and going to seed.
 For the adventurous gardener, hairy bittercress is an edible green. Tender leaves collected in early spring or late fall can add a peppery taste to salads.

As the winter progresses, keep an eye out for hairy bittercress and get ready to weed as the weather warms up!

Photos: Emma Erler

An Unwanted Garden Invader

Phytolacca americana

Over the past couple months you may have noticed a large, shrubby plant with reddish stems and beautiful purple-black berries. What you are seeing is Common Pokeweed, Phytolacca americana. Although I often find it attractive, pokeweed is generally considered an unwanted garden invader.

Pokeweed is a native herbaceous perennial. It can grow one to three meters tall and resembles a small tree. The large, thick stems are smooth and upright, while the leaves are alternate, egg-shaped and pale green. Pokeweed is supported by a large fleshy taproot that persists through the winter after the succulent stems have died back.  Pokeweed flowers are small and white and give way to conspicuous green berries that ripen to a deep purple-black color. Even though the fruit may look tempting, don’t eat it! All parts of the pokeweed plant are poisonous, including the berries.

In natural areas, pokeweed is an important wildlife plant. Berry-eating birds, such as Northern Mockingbirds, American Robins and Cedar Waxwings, load up on pokeweed berries. Many mammals including gray fox, raccoons, and white-footed mice enjoy the fall fruit as well. Both birds and mammals are directly responsible for the spread of pokeweed seeds. Despite pokeweed’s wildlife benefits, it is generally considered a weed in the cultivated landscape. Pokeweed grows very quickly and will shade out desirable bedding plants if it is allowed to grow. In many cases, pokeweed is not an aesthetically pleasing addition to a garden bed.

Pokeweed is fairly easy to control once you have identified it. The plant can be destroyed simply by digging up the taproot with a spade or soil knife. If possible, try to remove plants before they form fruit. Otherwise, the animals in your area will help spread this weed throughout your yard. Although it is probably too late to stop the spread of seeds this year, keep an eye out for new plants in the spring. In the meantime, happy weeding!

Photos by Emma Erler