How To Grow Rhubarb Like A Pro

Rhubarb is a wonderful cool-season vegetable that mostly shows up in sumptuous desserts! It is easy to grow and supplies nutritious stalks for many years. In this article we will explore how to grow, care for and harvest rhubarb.

Quick Facts

Botanical name: Rheum rhubarb L.
Height: 2.5 to 3 feet (0.76 to 0.9 m.)
Spread: 3 to 3.5 feet (0.9 to 1 m.)
Sun exposure: Full sun to part shade
Soil requirements: Well-drained soil with organic matter
Hardiness zones: 4 to 7
When to plant: Early spring or fall

Rhubarb is a hardy, early spring vegetable that reminds many people of their youth when grandma grew it. Only the stems (petioles) are edible but they are sour if eaten fresh. Most people grow it for use in desserts, often with strawberries and in pies, cakes, sauces, or jellies. It packs a punch of nutrients: Vitamins A and C, thiamin, niacin, riboflavin, and dietary fiber.

Since it is a perennial vegetable that can produce for more than 10 years, plant it on the edge of your vegetable or ornamental gardens so it won’t be in the way of your annual plantings.

A word of warning: The leaves and roots of rhubarb are toxic. They contain high levels of oxalic acid along with anthraquinone glycosides that should not be consumed. However, the edible stalks also contain small amounts of oxalic acid, but you would have to eat large amounts of the stalks to be affected.

Tips for Growing Rhubarb

Here are some tips on how to grow rhubarb, how to care for the plants, and how to harvest juicy home-grown rhubarb.

Light

Rhubarb should be planted in a full sun site but it can tolerate part sun.

Water

Rhubarb plants need 1 inch (2.54 cm.) of water a week during the growing season.

Temperature & Humidity

Rhubarb is a cool-season vegetable that thrives in spring. It needs temperatures less than 75 degrees F (24 C.) to grow well. The leaves will die back with the first hard frost.

Soil

The soil should be well drained with lots of organic matter. Loamy soil is preferred to other types but it can tolerate all soils. Add compost or well-rotted manure to increase the organic matter and fertility so the plant will thrive for years.

Fertilizer

When planting, add a fertilizer labeled 11-15-11 into the soil (2 cups per 100 square feet of space) or add generous amounts of compost. Rotted manure will increase the organic matter.

Each year thereafter, side-dress with 3 ⁄ 4 cups of 11-15-11 fertilizer per plant in early spring when new growth starts. After harvesting, apply a second fertilization of ½ cup of nitrogen only such as 16-0-0 to promote leafy growth during the summer.

Problems, Pests & Diseases

Rhubarb requires little maintenance once established and is not usually bothered by pests and disease. In soil that is not well drained, however, it can succumb to root rot.

Leaf spot diseases may occur. If it does, pull the infected stems and discard them. Also, discard all the foliage after the first hard frost.

Occasionally, rhubarb will show symptoms of a virus – discolored leaves and abnormal growth. It is best to discard a plant suspected of being infected with a virus.

Rhubarb curculio is a snouted beetle that can bore holes into the stalk and crown. Stalk borers also can bore holes into the plant. Be sure to remove grassy weeds as they will attract these insects. Curly dock is a host plant for rhubarb curculio.

Pruning

Pruning is not necessary except to remove damaged leaves, flower buds, and seed stalks. If the plant goes to seed, remove the seed stalk as soon as you notice it. It is a waste of energy for the plant to produce flowers or seeds.

Propagation

You can divide rhubarb every six to 10 years. Using a sharp shovel, cut the clump into halves or thirds. Replant in a new area and share some of the divisions.

Rhubarb can be started from seed about six weeks before the last spring frost. Lightly cover the seed and keep it moist. Harden off the plants before moving outside.

Plant crowns 2 to 3 inches (5 to 7.6 cm.) deep in the soil. Allow about 3 feet by 3 feet (1 by 1 meter) of space for one plant, which is usually sufficient for a family. Mulch around plants to discourage weeds and warm the soil.

Harvesting

Harvest rhubarb stalks in spring when it is established. Do not harvest the first year and only harvest a few stalks the second year. The third year and thereafter, harvest until the stems start to thin in early summer (about 8 to 10 weeks).

Always leave about one-half of the plant unharvested so it can replenish for the next year.

To harvest a stalk, grasp the stem at the base and twist. Store fresh rhubarb in the refrigerator for two to four weeks.

Remove and discard the leaves or add them to the compost pile. Even though the leaves contain oxalic acid, it decomposes rapidly and won’t affect the compost.

Varieties

Varieties vary in color from green to almost red. The redder varieties look more appetizing in desserts than the greener varieties that may turn gray when cooked. Recommended cultivars for USDA zones 4-7 include MacDonald, Crimson Red, Victoria, Canada Red, and Cawood Delight. Cherry, Ruby, and Strawberry varieties are desired for their bright red stalks.

FREQUENTLY ASKED QUESTIONS

Is rhubarb toxic? The leaves and roots are toxic and should never be eaten. The stalks are edible although they, too, contain small amounts of oxalic acid and should not be eaten in large quantities. People with certain conditions may want to avoid rhubarb altogether: Kidney disorders, gout, rheumatoid arthritis,
Does a late freeze force oxalic acid into the stalks? No scientific evidence to prove or disprove that theory is available, but stalks that suffered a late freeze would be frozen and mushy, and likely unappetizing. It is probably wise to err on the side of caution and avoid eating frozen stalks.
Can I harvest stalks in mid summer? Although you need to stop harvesting in early summer so the plant can replenish, it is okay to occasionally harvest during the summer for a special event. It will not harm the plant.
Can rhubarb be frozen? Yes! You can store rhubarb in the freezer while you wait for other fruits and vegetables to ripen to serve with it.