Although yellow dock is not a plant that most home gardeners would name as their most-dreaded weeds, it is important to keep an eye out for it. Yellow dock is a tall perennial with long, sword-like leaves that have curly edges. Its seed head stands out even during the winter. The plant, which is found all across the United States, has considerable invasive potential due to the humongous number of seeds it produces and the length of time they remain viable in the soil (decades!). Therefore it is crucial that you remove yellow dock from your yard as as soon as you spot it. Many weeds are obscure plants that are easy to miss, but yellow dock is a weed that stands out so identifying it is relatively easy.
Yellow dock is mildly toxic to humans and toxic to pets.
|Common Name||Yellow dock, curly dock, narrowleaf dock, sour dock|
|Botanical Name||Rumex crispus|
|Plant Type||Perennial, herbaceous|
|Mature Size||1.5-4 ft, tall|
|Hardiness Zones||4-8 (USDA)|
|Native Area||Europe, Asia, Africa|
|Toxicity||Toxic to humans. toxic to pets|
Invasiveness of Yellow Dock
Yellow dock has become naturalized across much of the world. In some states of the United States, including California and Oregon, yellow dock is considered an invasive plant.
While the plant's hardiness range is commonly listed as USDA zones 4 through 8, it is found almost anywhere in the United States even in warmer climate zones and in Alaska. This widespread distribution is not surprising, as yellow dock is native to Africa, temperate and tropical Asia, as well as Europe.
Yellow dock often tolerates poor, disturbed soils although it prefers to grow in rich, loamy soils in full sun and with adequate water. It often grows in overwatered soils or areas of standing water and in irrigation ditches. It is equally found along roadsides and in wasteland, on cultivated farmland, and in pastures, creating a problem because yellow dock is not only toxic to pets but also toxic to cattle and sheep.
Each plant produces between 40,000 and 60,000 seeds depending on the source, and they are dispersed from late summer through the winter. This huge number of seeds is combined with their extreme viability—seeds can survive in undisturbed soil for more than 50 years. Where yellow dock spreads, it chokes out crops and native plants, depriving them of nutrients, sunlight, and space.
Another problem of yellow dock is that the plant is an alternate host for several crop diseases caused by viruses, fungi, and nematodes.
What Does Yellow Dock Look Like?
Yellow dock belongs to the buckwheat family, which is identified by the nodes that punctuate the plant's stems. Young seedlings are either entirely green or take a red tinge in cooler months. Mature plants have dark green leaves or bluish-green leaves. The bottom leaves can be quite long, ranging from 1/2 foot to 1 foot in length. Look, in particular, for the sword-like shape and the curled or wavy edges of the foliage. As the leaves age, they become reddish-purple.
The distinct flower head of the plant that remains after the blooms have dried and turned reddish-brown is helpful for the identification of yellow dock. The flowers start out a much less distinctive light-greenish color (they can have a reddish tinge, too). Blooming occurs in clusters in the form of multiple, long, skinny flower stalks at the top of the plant.
Another aid in identifying the plant is its height. The plant reaches as much as 4 feet tall at maturity.
The fleshy, smooth stems with a reddish color die back in the fall. Yellow dock has a large, deep taproot that is yellowish-orange in color.
How to Get Rid of Yellow Dock
As long as the plant is small, you can dig it out with a shovel or a spade. Hand-pulling is not a good option because the long taproot will likely rip and the plant regrows from any root segments.
Removing mature plants with their entire tap root is challenging. Instead of trying to dig it out, cut any vegetative growth repeatedly starting in the spring in order to gradually exhaust the plant’s energy reserves. Once the plant is weakened, it will still need to be treated with an herbicide such as glyphosate, clopyralid, triclopyr, or 2,4-D to eradicate it. If you are dealing with a large infested area, you can also mow it repeatedly.
Yellow dock does not do well when it has to compete against other vigorously growing plants so after you remove it, replant the area promptly. Given the large number of seeds of yellow dock and their long viability, there will likely still be seeds in the soil but the presence of other plants or crops will make the reemergence of yellow dock less likely.
How to Prevent Yellow Dock from Spreading
Cutting down yellow dock before it starts its long flowering period, which can stretch from June into September, is the most important thing you can do to prevent its spread.
Is curly dock and yellow dock the same thing?
Yes, those are two different common names for the same plant, Rumex crispus.
How can I tell yellow dock apart from broadleaf dock?
Broadleaf dock (Rumex obtusifolius) is a related weed that can also grow to be as much as 4 feet tall. It is easy to tell the two apart: True to its name, the broadleaf type has bottom, or "basal" leaves that are very wide (4 inches across, versus 1 inch across for yellow dock plants). Curly dock has basal leaves shaped like swords, the basal leaves of its broadleaf dock are shaped more like shields.
When did yellow dock come to the United States?
The exact time is unknown but it has been on the North American continent since colonial times. The first spotting goes back to the 1700s.
Rumex crispus. North Carolina State University Cooperative Extension
Rumex crispus. North Carolina State University Cooperative Extension.
Curly Dock. Invasive Plant Atlas of the United States.
Curly Dock. Utah State University Extension.
Curly Dock. Washington State University Extension Whitman County.
Curly Dock. Iowa State University Extension and Research.