Docks were popular wild edibles during the Great Depression due to their tart, lemony flavor, their widespread abundance, and the fact that they were free for the taking. Today, most people have forgotten about this common and tasty edible weed.
Docks are perennial plants growing from taproots, and they are most often found in neglected, disturbed ground like open fields and along roadsides. While docks may be happiest and tastiest when they grow with plenty of moisture, the taproot indicates they are drought-tolerant plants. Docks grow as basal rosettes of foliage in early spring; they are often one of the first greens to emerge. By late spring or early summer, dock produces tall flower stalks that bear copious amounts of seed, which are also edible. The seed, however, can be labor-intensive to process and reports on its palatability are highly varied.
The foliage of mature dock plants may be from one to three feet tall, depending on growing conditions, but in early spring, when it's at its most delicious, the smaller plants may be hard to spot. Look for the tall, dark brown, branched flower stalks that produced the prior year's seed crop. These often remain standing over winter and new growth will emerge from the base of the stalk.
Which Docks Are Edible?
There are many edible docks, but curly dock and broad-leaved dock are the most common in the USA and Europe. Other edible docks include R. occidentalis (western dock), R. longifolius (yard dock), and R. stenphyllus (field dock). R. hymenosepalus (wild rhubarb) is common in the desert in the American Southwest. It is larger and more succulent than many other docks. It has been a traditional food and dye source for several Native American tribes.
Patience dock (R. patientia) was once cultivated as a vegetable in both the USA and Europe and is still grown as such by a small number of gardeners. Patience dock may be found as a feral plant. It's larger, more tender, and perhaps more delicious than any other dock plant. Seeds can be found for sale online.
One of the best identification features for docks is the thin sheath that covers the nodes where leaves emerge. This is called the ocrea, and it turns brown as the plant ages. The condition of the ocrea may be a good indicator of how tender and tasty that dock plant is. A second excellent identification feature is the mucilaginous quality of the stems. Know that only young dock leaves are covered with mucilage.
The sour flavor of dock comes from oxalic acid, which, when consumed in large quantities, may cause kidney stones. The same compound is found in spinach. If eating spinach is against physician's orders or for those who are prone to kidney stones, don't eat dock. Now, for those who are generally healthy and don't eat large quantities of dock on a regular basis, it should be fine. For those who are nervous about this, err on the side of caution.
Curly dock may also be called yellow dock, sour dock, or narrowleaf dock, depending on where they are purchased. Common names are tricky for that very reason; they change from place to place. For those who need to know precisely and with absolute certainty which plant they're dealing with, use the botanical Latin name.
How and When to Harvest
Both curly and broad-leaved dock are edible at several stages. The most tender leaves and the best lemon flavored ones come from young docks with flower stalks that have yet to develop. Pick two to six youngest of the leaves at the center of each clump. They may not even have fully unfurled, and they will be very mucilaginous.
From early to mid-spring, young leaves are tasty raw or cooked. If using raw leaves, avoid excessive mucilage by removing the leaf stem (petiole) and using only the actual leaves in salads.
The midribs of large dock leaves can be tough and fibrous, while the leaf blade remains tender. If a plant with tasty foliage but tough midribs is found, remove the midrib from the leaf before cooking. Additionally, larger petioles may be tough but pleasantly sour. Consider chopping the petioles into small pieces, and cooking them as a substitute for rhubarb or Japanese knotweed.
In the Kitchen
Like so many greens, docks reduce in volume when cooked, by about 20 to 25 percent of their original volume.
Boil or saute dock greens to make the most of their flavor. They are excellent in stir-fries, soups, stews, egg dishes, and even cream cheese. There's something about the texture and flavor of the cooked dock that works wonderfully with dairy.
Because dock has a relatively short harvest season, like so many wild greens, harvest as much as you can when it's at its peak, then blanch and freeze for later use. Dock is considered an invasive weed in fifteen states, so foraging probably won't make a dent in the local population. Try vacuum sealing and freezing a bag of dock for winter months when the promise of spring greens seems like a cruel culinary tease.