Wednesday, January 20, 2010

Serving Up Rhubarb

Photo by Evan Amos

Rhubarb is a favorite for many folks, but to others it's practically unknown.  Garrison Keillor, creator of A Prairie Home Companion radio show, sang his famous lines, "Mama's little baby loves rhubarb, rhubarb, Beebopareebop Rhubarb Pie", and made us feel nostalgic for it even if we'd never eaten it.

Rhubarb has an interesting history.  Native to Asia, it has been used as medicine there for a very long time.  The plants grew wild along the Volga River.  It is said that some early Americans consumed the leaves, but paid for it with their lives because they didn't know that the leaves and roots of rhubarb were toxic to humans.  How they came by it is unclear.  Only the leaf stem or petiole is edible.  Not surprisingly the use of rhubarb for culinary purposes was apparently abandoned until someone discovered many years later that they had eaten the wrong part of the plant.  On the other hand, historians tell us that rhubarb was so highly regarded as medicine by Chinese that they considered it too valuable to share with the common rabble in Europe.

Rhubarb is a versatile and beautiful perennial plant that does well in ornamental and vegetable gardens from USDA climate zone 8 and upward.  The large leaves are bold in appearance, and the colorful petioles (red, pink or light green) are very attractive.  Even if not eaten, it would be worth growing in the landscape or containers for beauty alone.

Choose a site in full sun with rich, well-drained soil where the plants can be left to grow for decades.  In the south, rhubarb can suffer from the sun's heat, so planting in partial shade is helpful.  Soil pH should range between 5.8 and 6.8.  I recommend taking a soil sample to your local Cooperative Agricultural Extension Service for testing.  Call them first for instructions and fees.

When the soil has warmed and danger of frost is past, cultivate the soil deeply and well.  Add lots of composted organic matter and any other soil amendments that the soil test result indicates.  Once planted, you won't have an opportunity to cultivate the soil so well again.  Do it right the first time.

Though the roots you purchase commercially may seem small (usually no more than one and a half inches long), they will grow large if well-maintained.  Plant them about three feet apart.  Dig a hole large enough in the soft soil to accommodate the roots without crowding.  You may make a cone-shaped mound in the bottom of the hole and spread the roots over it.  The buds, or "eyes", should be two to four inches below the soil surface.  Gently press the soil over the plant and water well, taking care not to wash the soil away from the crown.

When new growth appears, begin adding composted mulch or straw around the plants.  This will help to conserve moisture, prevent erosion and suppress weeds.  Weeds compete for nutrients and moisture.   Even without weed competition rhubarb needs watering, so provide at least one inch of water per week during the growing season if rainfall is not adequate.  Remove seed stalks when they appear for the maturing seeds diminish the vitality of the plants.

When the plants die back in the fall, gardeners in the north may add composted mulch.  Southern gardeners, however, should remove mulch because rhubarb benefits from cold winter temperatures.  Composted mulch should be replaced in the spring.  Repeat the process every year.

Resist the temptation to sample your rhubarb the first year.  The plants need to become well-established.  They are prevented from doing so if the leaves and stalks are removed.  You may harvest a few petioles the second year if you must.  Take more the next year and thereafter.  Petioles are ready for harvesting when they are about three fourths of an inch to one inch wide.  The amount you may harvest depends upon the vigor of the plants.  If the plants are not vigorous, removing too many leaves will weaken the plants further.  So it's very important to maintain healthy plants.

Rhubarb is not seriously bothered by insects and diseases, though aphids, borers and beetles may appear.  Insecticidal soap is effective enough against aphids.  Beetles may be removed by hand.  Little can be done about borers, but they are rare.  As with many species, selected companion plants can repel insects.  Rhubarb does well when grown near garlic and onions.  They also respond well when grown near roses and columbine.

Leaf spot may occasionally appear, but it can be controlled by gathering and destroying dead foliage in the fall.  If the planting site is not well-drained, crown and root rot may cause a problem.  But this can be prevented by choosing a proper site in the beginning.

Rhubarb has a pleasingly tart taste, especially when sweetened.  It should be noted that rhubarb became more popular in North America when sugar became readily available and cheap.

Its called "pie plant" for good reason as it ends up in pies more often than not.  But rhubarb can also be used in breads and other baked goods, drinks, and as vegetable entrees or side dishes along with various meats.  Rhubarb can be canned or frozen for later use.  Remember:  only the leaf petiole is edible; the leaves and roots contain oxalic acid, so are toxic to humans.

Give rhubarb a try.  You'll enjoy its beauty, flavor, and the pleasure of growing a bit of history in your own backyard.

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