Rhubarb, Rhubarb

Rhubarb

In spite of my busy summer in 2014 I continued with plans to make a new garden for perennial vegetables. I had earlier decided that trying to mix perennial beds with annual crop plants wasn’t working well so it seemed a good idea to make new gardens and keep the annual and perennial crop plants separate.

There are several plants for the northern perennial vegetable garden that are essential to its completeness. Rhubarb is one of the essentials. In Minnesota (where I live) many people in rural towns and even cities have a plant or two, often overgrown and untended, in their yards. In several places across the state there are annual local rhubarb festivals featuring pies, muffins, jams, jellies, and wines made from rhubarb’s sour stems. And then there is Beebopareebop.

Rhubarb (aka “pie plant”) is grown for its red or green sour leaf petioles (the leaf blades are toxic and the roots purgative, so don’t eat either of them) and is easy to grow and very prolific. It is also a very healthful food, too, providing generous amounts of potassium, vitamin C, and anti-oxidants. The roots, and to a lesser extent the leaf petioles, are storehouses of compounds with potential medical uses. Its roots can also be used to produce many types of colors for dyeing fiber. As a perennial it fits in well with a permaculture arrangement.

Biogeography and Natural History of Rhubarb
Before it was cultivated rhubarb was a wild plant. Rhubarb, including the cultivated species Rheum rhabarbarum, R. rhaponticum, and Rheum x hybridum (the name for cultivated hybrid varieties), is a genus of long-lived perennials in the buckwheat family (Polygonaceae). There are about 60 described species of Rheum occuring from western Russia and the Volga River, east to Kamchatka and northern China, and south to the Himalayan region.

As in any large genus of plants there are species that live in habitats that would make for poor gardening. For example Rheum compactum, a wild rhubarb, grows in open forests, shrub thickets, and in stony soils in mountainous areas from western Siberia to northern China. Another wild rhubarb, Rheum tataricum, grows in poor soils in dry areas of Zavolzhsky to the Aral-Caspian and Pribalhashsky regions. Both are edible and are used for food. They are also used in hybrid crossings to develop new hardy varieties of cultivated rhubarb.

History and Medicinal Uses
Species of rhubarb have been used and cultivated in China for thousands of years. The earliest written reference to rhubarb dates to about 300 BC in “The Divine Farmer’s Materia Medica” also known as “Shen Nong’s Herbal”. Very likely its use was even earlier as the primary source for the book, Shen Nong (“Divine Farmer”), is said to have lived around 2,800 BC. Known as da huang in Shen Nong’s Herbal, rhubarb (Rheum palmatum) is a medicinal plant useful for its purgative properties. Traditional Chinese Medicine also uses rhubarb for treatment of skin sores, burns, bleeding, menses problems, and in anthelmintic preparations.

Another reference to rhubarb, though later than Shen Nong, is by Dioscorides of Anazarbus (40 – 90 AD). Dioscorides was a Greek physician who wrote of a plant called “rha-pontic” that is apparently a species of rhubarb from Thrace near the Black Sea. His description of rhubarb and its medicinal properties as a laxative and an astringent is in his five volume work “De Materia Medica” which describes the medical properties of many herbs and an important document detailing medicinal plants known to the Greeks, Romans and other peoples of the Mediterranean region. If don’t read ancient Greek or Latin a summary of Dioscorides and others’ knowledge of rhubarb (besides many other things herbal and chemical) can be found “Therapeutics and Materia Medica, Volume 2” by Alfred Stillé written in 1864.

Rhubarb roots were a trade item between parts of northwest China (Tanduc), where it was cultivated, and Europe beginning sometime around the 14th century. The roots were used for their purgative properties and were more costly than spices like cinnamon. The purgative compounds in rhubarb roots are the anthraquinones emodin and rhein. New research has shown some promise in rhubarb compounds for treating diabetes and some types of cancer.

Rhubarb as Food
The use of rhubarb species as food, at least in Europe, was late coming. The first written recipe from England is from 1760 in the “Compleat Confectioner” by Hannah Glasse. An even earlier mention of rhubarb’s use as food is in the September 1739 correspondence between English merchant Peter Collinson and American botanist John Bartram where he writes that rhubarb stems may be cooked with sugar and cinnamon into a tart (“Rhubarb: More Than Just Pies” by Sandi Vitt, 2000). Collinson says of rhubarb to Bartram, “It is much admired here, and has none of the effects that the roots have. It eats most like gooseberry pie.” It may be that this use of rhubarb in Europe as a food coincided with the increase in the availability of table sugar which tamed its sour taste. Rhubarb has been eaten by peoples of south-central Asia for millenia. In Iranian cuisine it is used in meat dishes like Khoresht Rivas and in desserts like Sharbat-e rivas.

Many people eat rhubarb with sugar or some other sweetener or fruit like strawberries to offset the sour taste. I’ve grown to like its sour taste and mix a few spoons of cooked rhubarb with cinnamon and ginger over wild rice for breakfast. It is also good cooked in crisp using oatmeal as the crust with apple slices or sauce, some brown sugar, chopped walnuts, vanilla, cinnamon, and ginger.

Homegrown rhubarb over a dish of locally grown hand-parched wild rice. With the addition of apple sauce and wild plum sauce (both from fruit on trees I grow) this is a meal that supplies a serving of a high protein grain, two fruit servings and one vegetable (the rhubarb) serving.
Homegrown rhubarb over a dish of locally grown hand-parched wild rice. With the addition of apple sauce and wild plum sauce (both from fruit on trees I grow) this is a meal that supplies a serving of a high protein grain, two fruit servings and one vegetable (the rhubarb) serving. A good way to start the day.

Rhubarb can be made into light red wine and this is something I’m going to try this year. There are many recipes but I’m looking for one that doesn’t use almost as much sugar as rhubarb as I prefer a dry wine. It would interesting to make a vinegar from rhubarb wine.

Besides food, drink, and medicine, rhubarb also produces a dye. This can be extracted from the roots to produce red, brown, yellow, gold, and even pink colors depending on the mordant used.

Growing Rhubarb
A hardy plant, rhubarb can live for many years even if neglected. There is a green-stemmed rhubarb plant on my land that was growing when my parents moved here in 1970 (that was a mere 45 years ago). It was large and old then and it is really old now but still healthy. The plant hasn’t been tended to in 25 years and is being surrounded by grass and shrubs yet it keeps coming back each spring attesting to rhubarb’s tenacity. I plan to move some of it to a new location this spring so it can continue. There is a small patch of red-stemmed rhubarb my parents planted in the 1970’s also going strong. I took 12 cuttings from it a few years ago to start a new bed. Just five years later I was able to get 20 more large and vigorous cuttings for my newest rhubarb patch.

Rhubarb is easy to grow but does best on rich soil with good drainage in full sun with no weeds or grass competition. My newest rhubarb patch is for farm market production. I began preparing the site (about 50 by 40 feet) which was sodded with pasture grasses by tilling with a King Cutter rotary tiller in the fall of 2011 to start the process of killing the grasses and other plants. If you already have a prepared garden you don’t need such a drastic machine. A shovel will do. Soon after the ground froze I put down a thin hay mulch to protect the soil for the winter.

The following year in 2012 I started a cycle of tilling followed by cover crops of buckwheat mixed with oats and peas. When these were about six inches tall they were tilled under and new seeds planted. Cover crops add huge quantities of organic matter and capture nutrients that may have leached down. The cost of seeds is negligible. Also, leguminous cover crops like field peas enrich the soil with nitrogen and it only costs the price of bag of peas (about $20 for 50 pounds of peas which can go a long way). I left the last cover crop of buckwheat standing through the winter to protect the soil.

Manure piles in future rhubarb patch
Manure piles in the future rhubarb patch

In May 2013 I began adding manure and bedding from my sheep pen. I put down over 36 cart loads (one load = 16 cubic feet) the first time spreading them out to make a mulch about six inches thick. This was left for about six weeks, tilled under and a new layer of manure and bedding was added to cover the soil. The three seasons of preparation were necessary because my soil is poor, low in organic matter, and full of weed seeds. It needed a lot of improvement before it was ready for perennials of any kind.

In August it was time to plant rhubarb cuttings. Planting rhubarb is an easy task. Root divisions can be taken from mature plants in early May or in early August. To get root divisions it is best to dig up an entire plant and then cut it into pieces with at least one growing point (“crown”) and a few large roots attached. These should be planted immediately into the soil in holes 8 inches deep and wide enough to accommodate the roots and then cover so that the crowns are buried. The crowns should not stick above the soil. After planting they should be watered. Add more soil if any settling occurs. Rhubarb gets large so I made my rows four feet apart and planted the cuttings in the rows three feet apart. This will give them plenty of room to grow before they need to be divided again in about five years.

After planting lightly mulch each plant with clean hay or straw and mulch heavily in between plants and in the rows. New leaves will appear in a week or two and the plants will start growing new roots, too.

Newly emerging rhubarb leaves on April 20, 2014.
Newly emerging rhubarb leaves on April 20, 2014.

The following spring the plants will come out of dormancy and the first leaves (they are very colorful) will start to push through the soil surface. It is best not to harvest any rhubarb the first season. Let them grow all summer, weeding and watering when necessary. Competition from weeds will reduce plant vigor and yields. Also, cut out any flower stalks that form and continue this for the life of the plant as these use up a lot of energy better put to use in making leaf stalks. The second season after planting you will be able to make your first harvest, one that will be followed by many more. To keep the soil healthy apply aged manure or compost and mulch every fall.

One of thirty rhubarb planted in the summer of 2013 on May 16, 2014.
One of thirty rhubarb that were planted in the summer of 2013 on May 16, 2014.

Rhubarb suffers from few insect and disease problems and I have not had any problems. One insect that feeds on rhubarb is the rhubarb curculio beetle (Lixus concavus). The rhubarb curculio attacks the bases of leaf petioles and root crowns. It also feeds on near relatives such as dock (Rumex spp.) so keeping dock plants from growing nearby is a good way to control the beetle. Slugs are another problem for rhubarb and feed on stems and leaves. Slugs can be controlled by keeping the soil near the plants dry. Hand-picking of slugs may be necessary. Flea-beetles and aphids, which feed on a variety of plants, can sometimes feed on rhubarb. Most mildew and fungus diseases are able to infect rhubarb where air circulation and soil drainage are poor so planting in a sunny site with well-drained soil will reduce these problems.

This coming spring I will be putting in more root divisions of my red-stemmed rhubarb and root divisions of two named varieties called Chipman’s Canada Red and Crimson Red. I am also getting another area ready for a large red and green-stemmed variety of rhubarb called Victoria to be planted in early August. And I’m going to rescue that ancient green rhubarb plant, too.

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