Rhubarb is hardy perennial vegetable that will be ready for full harvest in the second or third year after planting. Rhubarb is best grown from root divisions planted in spring 4 to 6 weeks before the average last frost date or as soon as the soil is workable.
Description. Rhubarb is a hardy perennial grown for its edible stalks. Rhubarb leaves contain oxalic acid and should not be eaten. Rhubarb grows two 2 to 3 feet tall with large, green leaves on strong reddish stalks. Stalks grow up from a rhizome or underground stem sometimes called a crown. Rhubarb is harvested before flowering; remove flower stalks when they first appear.
Yield. Plant 2 to 3 plants per household member. Each plant will produce about 2 pounds of edible stalks each year.
Site. Rhubarb prefers organically rich, well-worked and well-drained soil with a soil pH of 5.0 to 6.8. Plant rhubarb in full sun or light shade. When preparing the planting bed, work in an inch of well-aged compost.
Planting time. Rhubarb is hardy vegetable that prefers cool weather. Set rhubarb root divisions in the garden 4 to 6 weeks before the average last frost date in spring or as soon as the soil can be worked. Rhubarb will take a year to begin harvest and four years to come to full harvest so planting time need not be exact. Rhubarb can be grown from seed but the plants will not grow true. Where summers are hot, stalks will grow thin and spindly; protect plants with shade cloth.
Planting and spacing. Set rhubarb root divisions or crowns 1 inch below the soil surface in mounds raised 6 to 8 inches. Space mounds 3 feet apart in rows; space row 3 to 4 feet apart. Set the growing tip slightly below the soil surface at planting.
Water and feeding. Keep the soil moist but not wet; do not let the soil dry out during the growing season. Make sure that the soil around rhubarb does not puddle in winter to avoid crown rot. Fertilize rhubarb beds with aged-manure in autumn and with aged-compost in spring. Side dress rhubarb with aged compost at mid season.
Companion plants. Artichokes, asparagus (also perennials) and cabbage family crops: Brussels sprouts, cabbage and kale. Avoid planting rhubarb near root crops.
Care. Keep rhubarb beds well weeded to avoid competition for light, water, and nutrients. To grow rhubarb with longer, thicker leaf stalks; cover the plant with a bottomless box in early spring. Cut flower stalks as soon as they appear. Where winters are cold cover plants with 1 to 2 feet of straw to protect the crowns from freezing; remove the straw in spring when the weather warms. Re-new rhubarb by dividing roots every four years; replant divisions in another part of the garden.
Forcing rhubarb. To force rhubarb to produce out of season, dig up crowns at least two years old and expose them to the first freeze in winter. Place them in pots or boxes filled with sand, and keep them moist in a place where the temperature stays cold but does not freeze. When you are ready to grow stalks for harvest, move the plants to a place where the temperature is about 60°F. Keep plants in the dark or cover them with a 2-foot-high box or pot to keep the light out. The plants will grow tall stalks with pale, folded leaves ready for harvest.
Container growing. Rhubarb is a perennial that requires cold dormancy for best production. Plants grown in containers must be allowed to reach dormancy. Plant in a container at least 12 inches deep.
Pests. Rhubarb has no serious pest problems.
Diseases. Rhubarb has no serious disease problems. Old clumps may develop crown rot if they are not divided every 3 to 4 years.
Harvest. Rhubarb is best harvested in its second or third year of growth after roots have established themselves. A light harvest of one or two stalks can be made the first year. Cut or twist outer stalks at their base when stems are 2 feet tall and plants are about 3 feet in diameter. Allow inner stalks to grow on. Do not harvest more than one-third of a plant’s stalks in one year. Do not eat rhubarb leaves which contain oxalic acid, a toxin.
Varieties. Canada Red; MacDonald’s; Valentine; Victoria (green stalks). Rhubarb will come to harvest about 90 days after plants begin growing in spring.
Storing and preserving. Rhubarb stalks can be stored in the refrigerator for up to two weeks. Blanched rhubarb can be frozen for 3 to 4 months. Rhubarb can be canned or dried.
Common name. Rhubarb, pie plant
Botanical name. Rheum rhaponticum
Origin. Southern Siberia