How To Grow Rhubarb

A favorite for generations of gardeners, rhubarb is a perennial vegetable that is often used like a fruit. Rhubarb stalks are harvested in the spring and used for pies, desserts and sauces. Its sweet-tart flavor is a wonderful complement to strawberries--and the two are often mixed for pies. While the stalks of the rhubarb plant are eaten, the leaves are toxic and should not be eaten.

Rhubarb can be grown from rhubarb seeds or plants. Rhubarb grows best in well-drained, loamy soil. To improve your soil structure, amend it with compost or soil-free mix. Rhubarb plants are heavy feeders--they require a lot of nutrients and water to produce those large stalks and leaves. Consider doing a soil test before planting and plan to fertilize annually with an all-natural fertilizer.

Where Does Rhubarb Grow Best?

Rhubarb goes well in many areas of the United States, and most rhubarb varieties will grow in zones 3-8. Rhubarb prefers cooler climates and can be a challenge to grow in warmer climates. For it to be grown as a perennial, rhubarb requires about 500 chill hours (when temperatures are below 40 degrees) in the winter.

Gardeners in warmer climates have had success growing rhubarb as annual. To do this, they start rhubarb seeds indoors in late summer and transplant the rhubarb seedlings to the garden in the fall.

Because rhubarb is a perennial plant, many gardeners plant rhubarb at the edge of the vegetable garden, in the flower garden or along a fence. Rhubarb can produce stalks for years and years, so select a spot with this in mind.

Rhubarb Sun Requirements

How much sun does rhubarb need? That depends on where you live. Gardeners in northern climates should grow rhubarb in full sun, or 6-8 hours of direct sunlight daily. For the best garden performance, also make sure that rhubarb receives adequate amounts of water.

For the most part, rhubarb thrives in cooler climates and has few pest and disease problems. In fact, under the right conditions, some northern gardeners are able to harvest rhubarb well into the summer months.

Growing Rhubarb in the Shade

Growing rhubarb in the South can be a bit of a challenge. In warmer climates, rhubarb performs better if it receives afternoon shade. Direct afternoon sun can burn in the leaves. When growing rhubarb in warmer climates, be extra diligent about watering the rhubarb plants.

Also, keep in mind that some rhubarb varieties are better suited for warmer climates. Often, the red varieties perform better. When selecting rhubarb plants for sale, select rhubarb varieties that are better suited for warmer climates.

How Do You Harvest Rhubarb?

Wait to harvest rhubarb the second year after planting if growing from plants or the third year if starting rhubarb from seed. When the stalks reach full length, hold the stalk firmly, twist and pull. Do not harvest rhubarb with a knife. After harvesting the stalks, cut off the leaves with a knife and discard the leaves. Depending on where you live, you may harvest rhubarb until early summer.

Later in the harvest season, rhubarb plants may produce seed stalks. If seed stalks emerge, cut them off.

Rhubarb plants can often be divided about every five years. Division is usually done in early spring.

Expert Advice

Q. We love rhubarb, but many years ago our huge patch died and we were told there was a disease in the soil. Since, then I have tried many times to start new crowns in other spots. The roots go in a deep rich hole and the shoots come up beautiful, but the leaves start to go brown and brittle when they are about 5 inches in size. Soon, the plant withers and dies—but amazingly, comes back the next spring. Can you help? I'm dreaming of rhubarb pie and jam!

---Bob in Springfield, Ohio

A. I have always been fascinated by the oddities of rhubarb: 'the only vegetable we use as a fruit'; and the only garden crop whose leaves are toxic, but whose stalks are safe to eat. (Unless you're highly sensitive to oxalates, as there are low levels of those crystalline-like structures in the stalks as well. Oxalate-sensitive individuals must also avoid spinach and some other foods.) Anyway, we devoted a lot of ink to this popular plant during my time as Editor of ORGANIC GARDENING magazine; and here's a condensation and compilation of our best growing advice:

Rhubarb can be planted Spring or Fall. Unless you're sharing someone else's root divisions, the plant will arrive in the form of a crown with eye-like shoots on top. Dig a deep hole—about the size of a bushel basket—and then mostly fill it back up with rich organic matter—compost, well-aged manure—and some sand or soil-free mix, if your soil is heavy. Place the crown in the center of this richness, so that the buds are a few inches below the soil line, cover with more manure and compost and then mulch over top with compost, manure, shredded leaves or straw.

rhubarb grows best in climates with lots of rain, and has what's known as a 'chilling requirement'; it needs a certain number of nights in the 40's and below to produce well. In naturally cold climates, plant rhubarb in full sun. If you're trying to get it to do well in the South or Hot West, make sure it gets afternoon shade and lots of water.

Although good drainage is essential, rhubarb requires a lot of water. New plantings must be kept moist if rain is scarce; and even established plants need to be watered at least an inch a week anytime it doesn't rain during the growing season.

Most sources say not to harvest any stalks the first year and to only harvest lightly the second year—otherwise the crown will peter out prematurely. When harvesting, try and twist the stalks away from the plant rather than cut them. And, of course, remove and discard every tiny bit of the poisonous leaves.

To produce their best, the plants will need to be dug up and divided every five years or so—ideally in very early Spring, before the new growth begins.

Most sources also agree that rhubarb suffers few to no pest or disease problems. So, my diagnostic guesses for the failure in Ohio are: poorly draining soil, lack of watering attention during dry times, lack of sun and/or not enough food. Rhubarb is a HEAVY feeder that wants to be top dressed with lots of compost and aged manure every season.

And it's no surprise that 'dead plants' came back in Ohio. Although you can stress it, rhubarb is hard to kill in cool climes. In fact, it likes to grow so much that real enthusiasts can sometimes harvest a patch all summer long (not just in Spring) by providing shade in hot times, lots of food and water, and harvesting the stalks promptly.

Q. Do you think I'm too far south for rhubarb to do well? My "USDA Zone" is supposed to be 7, but sometimes I see it listed as 8. (I must be just on the line.)

---Delma in Coastal NC

Can rhubarb be grown here in Central Texas? (We're about 20 miles west of Waco; Zone 8.) We are transplants from South Dakota and really miss fresh rhubarb.

---The Rev. Tom; St. Paul Lutheran Church; Crawford, TX

A. The farther South you get, the more rhubarb needs afternoon shade and lots and lots of water. The varieties known as 'cherry' and 'cherry red' are said to have the best chance of perennializing in the South; but in really hot climes, rhubarb must be grown as an annual crop, planted fresh each year. Hot-weather rhubarb fiends start their seeds indoors (just like tomatoes) in August, transplant the starts outdoors at eight weeks of age into fertile, well-drained soil and harvest stalks December through April—after which the poor plants just burn up in the heat.

Q. My Rhubarb, two years old and growing beautifully, has just developed what look like flowers forming on the top. Should I cut them off to let all the energy go into the fruit stalks (of which I have about 7)?

---Tony, just outside Philadelphia on the Main Line.

A. Yes, cut 'em off. Flowers draw needed energy from the crown and should be removed promptly. (They're also not very pretty, and any seeds they produce probably would not grow usable rhubarb.)

Q. Hi Mike! Love your show and thought you might like this short video on growing rhubarb indoors here in the UK. Enjoy!

---Marc in London

A. Thank you, Marc—the video is wonderful, and it looks like folks who live just about anywhere could utilize this amazingly simple technique to grow premium rhubarb. All you need is a cellar! Check it out.

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