Rhubarb is one of the first crops of the year. The plant emerges when temperatures rise into the 40s. Rhubarb is a vegetable that requires cold winters to grow. As a result, it’s mainly found in mountainous and temperate regions around the world, especially in Northeast Asia. It’s also a common garden plant in North America and Northern Europe.
Stems harvested in early spring will be the most tender and flavorful. Rhubarb is naturally tart. Do not wait to harvest or buy in the store stalks that are too big around. It is a sign they are mature and they can be pithy and tough especially when hit by hot weather or drought. These thicker stems can be used for stewing, sauces, and jams.
Rhubarb has slender green and red stalks, with large, ruffled green leaves. It is legally classified a fruit, but rhubarb is technically it’s a vegetable.
The sour taste is mainly due to malic acid and oxalic acid and due to its sour taste, it’s rarely eaten raw. It wasn’t until the 18th century, when sugar became cheap and readily available, that rhubarb became a popular food. Before that, it was mainly used medicinally. In fact, its dried roots have been utilized in traditional Chinese medicine for thousands of years.
Every 100-gram serving of rhubarb provides 29.3 micrograms of vitamin K, which supports healthy bone growth and may limit neuronal damage in the brain. It contains infection-fighter vitamin C, along with vitamin A, another powerful natural antioxidant for good skin and mucous membranes, good vision, and possible protection against lung cancer.
Like other fruits and vegetables, it’s also high in fiber, providing similar amounts as oranges, apples, or celery.
A 3.5-ounce serving of cooked rhubarb with added sugar contains:
- Calories: 116
- Carbs: 31.2 grams
- Fiber: 2 grams
- Protein: 0.4 grams
- Vitamin K1: 26% of the DV
- Calcium: 15% of the DV
- Vitamin C: 6% of the DV
- Potassium: 3% of the DV
- Folate: 1% of the DV
Rhubarb has folate, riboflavin, niacin, B vitamins and pantothenic acid. Good mineral sources include 12 milligrams of magnesium per 100-gram serving, along with iron, potassium and phosphorus.
One cup of cooked rhubarb contains 83 milligrams of calcium. Michigan State University lists rhubarb as one of the top “fruits” you can eat to get your regular dose of calcium.
Studies show that rhubarb’s polyphenol content may be even higher than that of kale. The antioxidants in rhubarb include anthocyanins, which are responsible for its red color. Rhubarb is also high in proanthocyanidins, also known as condensed tannins.
Rhubarb may be high in oxalates and should be eaten in moderation but cooking reduces its levels. Make sure to avoid the leaves.
How to Buy
- Harvest (or buy in the store) rhubarb stalks when they are about as thick as your finger and at least 8 inches long.
- Stalks 12 to 18 inches long and longer will be most tasty.
- Color also varies: ‘Victoria’ and ‘Linneaus’ have green stalks that blush a little red near the base; cultivars such as ‘Ruby’, ‘Valentine’, and ‘Canada Red’ have solid red stalks.
- Rhubarb is a perennial plant. A rhubarb clump will be productive for 20 years or more. Do not harvest rhubarb the first year after planting from seed. The second-year harvest a few stalks over a four week period. The third-year after planting and the following years, harvest as many finger-thick-sized stalks at you like over eight to 10 weeks.
How to Store
Cut away the leafy top leaving only the colored stalks. Do not eat raw or cook rhubarb leaves or roots they contain oxalic acid which can cause convulsions, coma, and death (but you have to eat a LOT of them for this to happen). The leaves are safe to compost.
Fresh harvested stalks are best for cooking and freezing.
Store rhubarb in a cold and moist place, 32°- 40°F and 95 percent relative humidity. Cold and moist storage can be a challenge. Refrigerators provide the cold, but they also dry the air. Wrap rhubarb stalks in a damp cloth or paper towel and put them in the vegetable crisper drawer of the refrigerator which will maintain humidity.
Cut stems will keep in the refrigerator for two to four weeks. Refresh stalks kept in the refrigerator by letting them stand in a glass of water before using it.
Chopped stems can be frozen in a silicone freezer bag for later use.
How to Cook
Rhubarb is most often served cooked in some manner because of its incredibly tart flavor when eaten raw. While you can find recipes featuring raw rhubarb, they often involve soaking it in honey or another natural sweetener to make it palatable. As for the sweetener, keeping it as minimal and as organic as possible is always the best.