Rhubarb is an herbaceous, cool-weather perennial vegetable that grows from short, thick rhizomes. It produces large, triangular-shaped poisonous leaves, edible stalks and small flowers. The red-green stalks, which are similar to celery in texture, have a tart taste and are used in pies, preserves, and sauces.
The leaves contain the toxic substance oxalic acid, a nephrotoxic which is damaging to the kidneys and may be fatal in large amounts but generally causes shortness of breath, burning sensations in the mouth and throat, coughing, wheezing, laryngitis, and edema. If the leaves have been ingested do not induce vomiting but call the Poison Control Hotline. Oxalic acid will migrate from the leaves to the stalks of plants that have been exposed to freezing conditions, therefore those stalks should not be consumed.
Soil Requirements Rhubarb has a wide range of acceptable pH, from 5.0-6.8 which makes it well-suited for a Connecticut garden. Have a soil test done through the UConn Soil & Nutrient Analysis Lab and follow the recommendations a year before planting if possible. Amending the soil with aged manure or well-rotted compost will increase plant production.
Location Selection & Planting Rhubarb should be planted in an area with full sun or light shade where it will be out of the way, at one end or side of the garden, as it will remain productive for 5 or more years. They should be planted in an area with good drainage or in raised beds.
Rhubarb roots may be planted or divided in the early spring while they are still dormant. Dig up roots that are more than 5 years old to divide them. The appearance of seedstalks or flowers is a sign that the plant needs division. Cut each root into 4-8 pieces ensuring that each section has a new bud and at least 2” of root. Newly divided plants should be put into the ground as soon as possible. The crown bud should be 2” below the surface of the soil. Plants should be spaced 3-4’ apart in rows that are also 3-4’ apart. Remove flower stalks the first year.
Starting rhubarb from seed is not recommended as all cultivars are hybrids and the resulting plant will not be true to the mother plant.
Water Requirements Rhubarb is fairly drought tolerant as plants can store water in their fibrous root systems which run 12-18” below the surface. During extended periods of hot dry weather plants should be watered deeply so that the soil is damp to a minimum depth of 3-6”. Mulch will suppress weeds and retain water but do not cover the crowns.
Fertilizer Rhubarb requires little to no fertilizer although ¾ of a cup of a balanced fertilizer (10-10-10) applied once a year in a ring outside of the stalks will benefit production
Harvesting Harvesting of rhubarb generally starts in mid-June. Do not harvest rhubarb stalks until the second year when stalks may be harvested for 1-2 weeks. After that, the full harvest period is 8-10 weeks. Pull the leafstalks off at the base by using a twisting motion and trim and discard the leaves. Wash the stalks well before using. Freshly harvested stalks can be refrigerated for a few days.
long, thick stalks, extra sweet
rich red inside and out, vigorous
Tall, plump, entirely bright red stalks
Tender skinned with a brilliant red that can fade in the summer heat, resistant to wilt, root rot
long petioles, few seed stalks
cold hardy, vigorous
speckled pink on green stalks
Diseases Fungal Leaf Spots Fungal leaf spots is more of an aesthetic issue as they affect the leaves only. Avoid wetting foliage if possible by watering early in the day so aboveground plant parts will dry as quickly as possible. Do not crowd plants by spacing them to allow air circulation. Eliminate weeds around plants and garden area. Remove and destroy or discard affected plant parts. Rake and dispose of all fallen or diseased leaves and stalks at the end of the season. Phytophthora crown rot This can be a problem in poorly drained soils. Botrytis Botrytis fungus causes leaf, stalk, and crown rot. This disease is common in areas where rhubarb plants do not receive proper air circulation and high humidity is present. Eliminate rotting material near the plants and apply a fungicide at 7 day intervals as soon as you notice the disease.
Young plants and transplants tend to be more susceptible to diseases.
Insect Pests Rhubarb curculio Rhubarb curculio, Lixus concavus, is a snout beetle that bores into the stalks, crowns, and roots of rhubarb plants. Feeding injury appears as notches on the stalks and leaf edges. The adult overwinters in debris near the rhubarb plants. They appear in mid-May to lay eggs in punctures that they make in the stalks of rhubarb as well as the alternate hosts of dock, thistle, and sunflower. The eggs laid in the rhubarb stalks get squeezed by the growing tissues and do not hatch. The removal of the alternate hosts from the area during July will reduce the populations. Adults can be hand-picked and destroyed.
Despite good cultural practices, pests and diseases at times may appear. Chemical control should be used only after all other methods have failed.
For pesticide information or other questions please call toll free: 877-486-6271.
Revised by the UConn Home and Garden Education Center 2017
The information in this material is for educational purposes. The recommendations contained are based on the best available knowledge at the time of printing. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The Cooperative Extension system does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available.All agrochemicals/pesticides listed are registered for suggested uses in accordance with federal and Connecticut state laws and regulations as of the date of printing. If the information does not agree with current labeling, follow the label instructions. The label is the law. Warning! Agrochemicals/pesticides are dangerous. Read and follow all instructions and safety precautions on labels. Carefully handle and store agrochemicals/pesticides in originally labeled containers immediately in a safe manner and place. Contact the Connecticut Department of Environmental Protection for current regulations.The user of this information assumes all risks for personal injury or property damage.Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Gregory J. Weidemann, Director, Cooperative Extension System, The University of Connecticut, Storrs. The Connecticut Cooperative Extension System offers its programs to persons regardless of race, color, national origin, sex, age or disability and is an equal opportunity employer.