curly dock with flower stalk

Now that winter is here, most of us don’t have to mow our lawns. Our flower gardens have probably fizzled out too, but we still have weeds. Curly dock (Rumex crispus) is one of those ugly coarse textured plants that will plague us for the next several months. Crispus is Latin for curly. I bet you figured that out.

Dock is what we call a biennial, meaning it completes its lifecycle in two years. Large elongated leaves grow in a circular pattern. Individual leaves can be two feet long. The lengthy taproot makes this invader hard to pull too. Yellow color of the root flesh is responsible for its often being called yellow dock.

In late spring this rhubarb relative will send out a flower stalk two or three feet tall. It’s edible but a little bitter. Leaves are too astringent to eat at this point too. Tannin content is too high.

When seeds mature they can be ground into flour and used like buckwheat, not surprising since they are in the same family. Seeds also can be roasted and used as a coffee substitute, explaining another common name, coffee-weed. Triangular-shaped winged seeds are dark brown. Each plant can produce 40,000 of them.

People eat leaves raw but they taste better cooked. I don’t like them quite as much as some other common greens like chickweed or lambsquarter, but they are phenomenally high in iron, namely organic iron compounds. Common inorganic iron compounds tend to bind and constipate but the laxative properties of curly dock mean an abundance of iron without constipation. Vitamins A and C are also plentiful. Like all greens curly dock is rich in fiber.

Young leaves are tender but somewhat sour. Oxalic acid among other things causes this, and rinsing the leaves removes some tartness. Foods high in oxalate may contribute to calcium oxalate kidney stone formation. Large doses of oxalates also increase inflammation, pain, and irritate tissues and mucous membranes.

Since dock is not a major human food source, overconsumption poses no problem. Nausea and diarrhea are possible if we eat too much, but we can get those symptoms from many foods.

Livestock frequently struggle with it though, as dock can be abundant in pastures. At certain times of the year it can comprise much of their diet. Sheep, in particular are very sensitive to oxalate poisoning and large quantities can be fatal. Consequently, livestock farmers try to eliminate it from grazing areas.

Curly Dock is difficult to control using cultural weed control methods. It withstands mowing and large variances in soil moisture. Even if roots are pulled, seeds still can live for more than 50 years. The most effective weed-killers are systemic ones that kill the whole plant. Several selective chemicals for broadleaf weeds will suffice. Pre-emergent herbicides prevent germination.

Historically, dock has been used to treat skin irritations, infections, hemorrhoids, anemia and menstrual problems. Improved liver function is also documented. Many commercial herbal extracts are available and formulated from both leaves and roots. Before trying anything consult your doc.

curly dock foliage

Ted Manzer teaches agriculture at Northeastern High School.