Growing Rhubarb in the Home Garden
By Joan Allen, UConn Home & Garden Education Center
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Purdue University |
If you enjoy the tangy, tart flavor of pies and sauces made from rhubarb, it is an easy to grow and attractive addition to the home garden. Rhubarb (Rheum rhabarbarum) is a cool season perennial vegetable grown for its leaf stalks. The best time to plant rhubarb is in early spring while the crowns are still dormant or just beginning to leaf out. Crowns can be purchased from seed catalogs or local nursery and garden centers. Some suitable varieties for Connecticut include MacDonald and Victoria. They should be planted as soon as possible after purchase. If storage is necessary, place them in the refrigerator. Rehydrate the crowns by soaking in water for two hours or overnight before planting.
Rhubarb prefers full sun but will tolerate partial shade. It can be planted in vegetable gardens or ornamental beds. Because it is a perennial, placing it at the end of the vegetable garden will avoid having it in the way when planting and caring for annual vegetables. Rhubarb plants get quite large and require a space about 3' x 3' to 4' x 4' in size. Loosen the soil to a depth of 10 inches and for each plant, mix in 3-4" of compost or well aged manure. A small amount of fertilizer high in phosphorus and potassium such as 5-10-10 or similar can be added as well. Refill the hole partway and place the crown so that it will be covered by 1 inch of soil. Pack the soil firmly around the roots and water well. Once the plants are growing, adding a layer of mulch will help control weeds and conserve soil moisture. Plants will benefit from the addition of fertilizer each spring.
To allow the plant to become well established, do not harvest any leaf stalks the first season. During the second season, harvest lightly. Beginning in the third season rhubarb can be harvested heavily. Harvest the largest stalks first. Stalks are ready to harvest when they are about as wide as your thumb. Pull the stalks from the plant by grasping the stalk near the base and pulling it slightly to one side. Mature rhubarb plants (beginning in the third season) can be harvested for a four to six week period. After this, the plants should be allowed to grow throughout the summer to replenish the carbohydrate reserves in the crown. The stalks can be harvested again just before the first frost but the quality will not be as good as that of the spring crop.
When a rhubarb crown is 6-10 years old, the stalks may be crowded and skinny. This indicates that the crown needs to be divided. Remove the crown from the ground with a shovel and divide with a spade, hatchet or other sharp tool. Each division should have at least one visible bud and be about the size of a fist. Follow the same planting procedure described for new crowns.
Rhubarb leaves are toxic because they contain oxalic acid and they should not be eaten. They can be safely added to your compost pile. The oxalic acid rapidly decomposes and does not affect the compost quality. Do not eat stalks that are injured by frost as cold injury can cause the oxalic acid crystals to move from the leaves into the stalks. This will be evident as soft mushy areas on the stalks.
Rhubarb plants produce flower stalks which are not good to eat. It is best to remove the flower stalks as soon as they appear because they deplete reserves in the crown that support vegetative growth. If you do decide to allow the showy white flowers to form, cut them off before they go to seed to minimize the depletion of the storage reserves.
Pests are not usually a problem on rhubarb in the home garden. In some locations, crown rot caused by soil-borne fungi can occur. If plants fail to leaf out in spring or the plant wilts, this may be the cause. Crowns with brown and rotted areas should be removed. Replant in a different location using disease free crowns from a reliable supplier. Insects and other pests that feed on rhubarb include the rhubarb curculio, mites, white flies and slugs. The rhubarb curculio is a yellow-orange colored snout beetle about 3/4" long that occasionally causes serious damage to the leaf stalks. Curly dock and sunflower are other hosts for this insect so these should be removed from the area if the curculio is a problem.
Historically, rhubarb has been used medicinally and also for the control of some garden problems. Medicinal uses have included treatment for diarrhea, constipation and fever.
In gardens, sticks of rhubarb have been used to prevent clubroot of cabbage and rhubarb tea was recommended to eliminate many insects. Modern gardeners still use tea from rhubarb soaked or boiled in water to control aphids, leafminers and red spider mites but its effects have not been verified by scientific study.
For more information about gardening, visit the UConn Home and Garden Center at www.ladybug.uconn.edu.
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