How Does Rhubarb Grow?

​

​USDA Hardiness Zones 1-13

 

Although best-known as an ingredient in jams and pies, rhubarb is actually not a fruit. It is a perennial vegetable with a tart, edible stalk that is usually sweetened with sugar. Rhubarb plants have poisonous leaves. In fact, the stalk is the only edible part of a rhubarb plant!

 

Rhubarb is a hardy plant that grows in all USDA Hardiness Zones. It prefers full sunlight and fertile soil and does well growing next to asparagus, as it shares the same requirements for nutrient-rich soil and sunlight. The stalks (petioles) vary in color from crimson red to light green. 

​

Seasonal Growth

 

Rhubarb grows year-round in warm climates. In colder weather, however, the aboveground portion of the plant withers at the onset of freezing temperatures.  

 

It takes a rhubarb plant approximately three years for a full, successful harvest needing about two years to develop well-established leaf stalks.  As a result, although it can be harvested in the second year after planting, the yield will be moderate.  

 

Health Benefits

​

Long before it was used as an ingredient in holiday pies, rhubarb was prized for its medicinal qualities. As far back as 5,000 years ago, doctors in ancient China prescribed rhubarb for its purgative qualities, to combat fevers and venereal disease, and to prevent the plague. Modern medical science may prescribe to different philosophies than the ancients, but there is no denying the nutritional benefits of rhubarb.

 

As early as 2700 BCE, rhubarb was prescribed for constipation relief. The high dietary fiber content in rhubarb (1.8g per 100 grams) helps to bulk stool and promote smooth and regular bowel movements. As such, rhubarb provides relief from gastrointestinal discomfort such as bloating and cramping, and plays a role in the prevention of diseases such as colorectal cancer. 

 

Rhubarb is one of the lowest caloric vegetables, and helps to speed the metabolism and burn fat. For this reason, it is often recommended for people struggling to lose weight.

 

Each serving of rhubarb contains 45% the daily value of vitamin K, which supports healthy bone growth. Vitamin K can also limit neuronal damage to the brain, and therefore may be linked to the prevention of Alzheimer’s disease.

 

One cup of cooked rhubarb contains as much of the mineral, calcium, as one cup of milk - and it’s more healthy than milk. At 105 mg of calcium per cup, one cup of rhubarb is approximately 10% the recommended daily value for calcium. Along with spinach and salmon, rhubarb is one of the most calcium-rich foods.

 

Antioxidant vitamins, C and A, are also present in rhubarb. Antioxidants such as lutein and anthocyanins found in rhubarb help promote heart, eye, immune system health, and aid in the prevention of cancer.

 

Rhubarb is rich in a compound called stilbenoid, which helps lower blood sugar levels in diabetics.

 

History

​

This history of rhubarb’s medicinal uses dates back to its native China where records as far back as 2700 BCE note that the plant’s roots were utilized for their laxative properties. Records also indicate that rhubarb was used in China to combat venereal disease, as well as the plague circa the Song dynasty (960 CE - 1127 CE).

 

Rhubarb was most likely exported out of Asia via the Silk Road. By the 1st century CE it was being imported to ancient Rome for medicinal purposes, including relief from inflammation and constipation. In medieval Britain, where rhubarb arrived in the 14th century CE, the vegetable was a pricey apothecary ingredient, lauded for its alleged abilities to purify the blood. During the 1500s, rhubarb was prized so highly for its medicinal properties that in France, it sold for nearly four times the price of saffron, the costliest spice.

 

Rhubarb was not utilized for culinary purposes until the 18th century. It appeared in its first recipe, rhubarb tarts, in 1760. The recipe is attributed to Hannah Glasse, who is also responsible for the first known recipe for Yorkshire pudding. By the 1850s, aided by the falling price of sugar, rhubarb pie was prized as a highly popular dessert in England.

 

In 1947, New York State passed a law classifying rhubarb as a fruit instead of a vegetable.   The legislation was passed in order to lower the tariffs on imported rhubarb, although its a vegetable in every sense of the word.

 

Propagation

 

Rhubarb is propagated by several methods. In home gardens, it is usually grown from seed or propagated by division of the root mass. 

 

Commercially-grown rhubarb is propagated by crown division or by tissue culture, a process that starts with test tube cultures of rhubarb growing tips, which are called meristems. The meristems are dissected out of buds and provided with nutrients and plant hormones that promote rapid multiplication.

 

Harvest

 

Rhubarb is not harvested after its first growing season. It requires at least one full season to establish leaf stalks. Although it can be lightly harvested during its second year, by the third year, leaf stalks are established firmly enough for a full harvest. If the stalks thin out, harvesting is stopped because it is is a sign that the plant’s food reserves are low. At least two stalks per plant are left on the plant to ensure continued production. A well-maintained rhubarb plant will produce harvestable leaf stalks for up to 20 years.

 

Rhubarb stalks are ready to harvest when they are 12 to 18 inches long. The the stalk is gently twisted off at its base, never cut or broken off.

 

Rhubarb leaves are poisonous, and are immediately discarded.

 

In areas that experience freezes, rhubarb stalks are covered with 2 to 4 inches of mulch after harvesting. A nitrogen-rich compost mulch will benefit the plant for its next growing season.

 

In the United States, rhubarb is grown commercially in the Pacific Northwest, California, and Michigan.  It is also grown in England, and has a long history of cultivation in Yorkshire.

 

Storage

 

Fresh rhubarb is stored unwashed in a vegetable crisper in the refrigerator and will last up to one week. 

Chopped stalks of rhubarb can be stored up to four days in the refrigerator.

 

Fun Facts

 

Today, rhubarb is most commonly sweetened with sugar and used as an ingredient in pies, tarts, and other desserts. On occasion, it is pickled, added to juices, or included in savory dishes.

 

Grow it yourself

 

One of the easiest ways to grow rhubarb is to divide the root crown in a process known as root mass division: 

 

1. Rhubarb used for root division should be at least four years old. Dig up the root ball in early spring, when early growth is just beginning, being careful not to nick or otherwise damage the crown. 

2. Use a shovel to divide the crown, cutting carefully through the rhizome between the emerging buds. Discard any divisions that show signs of root decay or rot. 

3. Prepare planting area by removing all weeds. Space rhubarb crowns approximately four feet apart, one to two inches below the soil line.

4. Plant root divisions in full sun, in a well-draining mixture of 50% soil and 50% nutrient-rich organic compost. Rhubarb is a heavy feeder, so do not skimp on the organic matter such as manure or compost.

Do not use chemical fertilizers when planting or during the first year of growth. Direct contact with nitrates may kill a rhubarb plant. 

1. Water rhubarb well during the summer and mulch generously with a heavy layer of cow manure or straw to provide nutrients, prevent weeds and retain moisture. 

2. After the first spring, apply a light sprinkling of high-nitrogen fertilizer to the ground as it thaws.

3. Dig and divide rhubarb root masses every four years. This may be done when plants are dormant in early spring or fall.