Is this the year you grow rhubarb?
Rhubarb is a visually dramatic, edible plant emerging now in the spring garden.
Its ruffled, deep green leaves can be up to 24 inches long and 15 inches wide. Grown for its tart stalks, botanically the leaf petioles of those enormous leaves, it is an heirloom vegetable that can fetch high prices during its brief appearance at local groceries.
Rhubarb ( Rheum rhabarbarum) is long-lived, disease-resistant and easy to grow. It was used in China as a medicinal herb over 3,000 years ago. The British first ate rhubarb leaves, which resemble that of chard, but found that they were poisonous, containing oxalic acid.
The ensuing cramps, nausea and sometimes death suppressed interest in the plant for about 200 years. By the late 18th century, Europeans had discovered that the tart stalks were safe to eat and perfect for tarts, giving rise to the nickname “pieplant.” It was brought to the Americas by settlers before the 1800s.
Rhubarb is a member of the buckwheat family and is technically a vegetable, but the USDA classifies it as a fruit. Classic recipes using the stalks include rhubarb pie, rhubarb crisp and strawberry-rhubarb preserves.
Rhubarb stalks are quite tart and in desserts they are paired with sweet fruits and plenty of sugar. More savory preparations include sauces, chutney and vinegar-based shrubs.
Starts of rhubarb can be purchased in the spring from nurseries or via mail order. Plant them in a sunny spot in rich, organic, well-drained soil. Make sure crowns are planted only 1-2 inches beneath the soil surface.
Rhubarb is typically included in the vegetable garden, but consider using it as an ornamental plant in the mixed border, where its bold foliage will add interest.
Do not harvest stalks the first season after planting, and do so sparingly the second season — about four stalks per plant. After year three, harvest at will, but be sure to allow at least half a dozen stalks in place to keep the plant thriving.
Harvest stems in the morning when they are at peak hydration. You can harvest rhubarb by cutting stalks with a knife or pruning shears, but a tried-and-true technique is to harvest by hand using a sharp twist. Grasp a leaf stem at the base of the plant, give it a quick twist and pull sideways to remove
the stalk. This method prevents injury to the rhizome; cutting can leave stubs prone to rot.
Rhubarb grows prolifically in cooler spring temperatures and slows down with summer heat. Harvest begins in spring and continues through early summer. Once the calendar flips from June to July, stop harvesting, as the petioles become tough and fibrous.
Remove no more than half of the plant at one time. By mid-summer, allow rhubarb to recover and put its energy into growth for the following year.
If a mature rhubarb plant develops a flower, cut it off at the base, keeping the plant’s energy directed toward foliage production. Crowded, overgrown plants suffering from decreased vigor can be dug and divided every 5-8 years.
To divide, dig up the entire plant and slice it into clumps that contain at least one or two buds and a good root system. Inspect divisions for indications of root rot as the crowded crowns may need to be discarded. Replant at the appropriate depth.
After harvest, remove leaves from the top of rhubarb stalks. Compost the leaves, which will break down the oxalic acid.
Stalks hold well under refrigeration for about two weeks. Pack them in plastic bags or sealed containers, and wrap cut ends in a damp paper towel to keep them plump and crisp.
For longer storage, freeze stalks. Wash, trim, and cut into desired size, then pack into freezer-safe containers. Rhubarb also can be canned. Should you choose this method follow only research-methods and recipes. Information: extension.psu.edu/preservingrhubarb
Commercially available rhubarb varieties vary in stalk color from pink to red to speckled to green. Red stalk cultivars include ‘Canada Red,’ ‘Crimson Red,’ ‘McDonald,’ ‘Valentine,’ and ‘Victoria’, a robust, green stalked variety, which is a reliable performer with substantial stalks.
Carol Papas is a Penn State Master Gardener. This volunteer program supports the outreach mission of Penn State Extension and provides research-based information on best practices in sustainable horticulture and environmental stewardship. Information alleghenymg@psu.edu or 412-482-3476.