Jennifer Schultz Nelson
Extension Educator, Horticulture
There are certain fruits and vegetables that seem to elicit a very strong positive or negative response depending on the person. Rhubarb appears to me to be one of those vegetables. I mentioned to my husband that I was writing about rhubarb this week and he responded with a resounding "YUCK!" As for me, no one in my immediate or extended family cared for rhubarb, so I grew up never eating it. When I actually had an opportunity to try it as an adult, I found I actually liked it.
Some people think rhubarb is a fruit since the dishes typically made with rhubarb are pies, jams, and desserts. But rhubarb is technically a vegetable. A fruit develops from what once was the female part of a plant's flower. Rhubarb is in fact part of the leaf, the petiole to be exact. This is the stem-like part of a leaf that attaches it to the main plant.
Interestingly enough, legally rhubarb is considered a fruit. In 1947 the U.S. Customs Court in Buffalo, New York ruled that rhubarb should be considered a fruit since it is used typically as a fruit would be. This ruling was a way for businesses to pay less tax on imported rhubarb since the tax rate for vegetables was higher than that for fruit.
Rhubarb has been used for thousands of years as a medicinal plant by the Chinese. It wasn't until the 17th century in England that there is any record of people using rhubarb as food. It is no coincidence that this coincides with the widespread availability of sugar, once a luxury only available to the wealthy.
By itself, rhubarb is incredibly tart. Most people cannot stand to eat it without ample amounts of sugar combined with it. This is why most often rhubarb is combined with other fruits such as berries or apples.
The edible portion of rhubarb most familiar to us is the petiole, commonly referred to as a rhubarb 'stalk'. The unopened flowers are also edible, considered a delicacy in northern Asia. The roots and leaves of rhubarb are poisonous. They contain oxalic acid, which is toxic to the kidneys. But you would need to consume a relatively enormous amount of the leaves—a 140 pound person would have to eat about one ounce of extremely sour leaves to begin to show symptoms of poisoning.
It's also worth noting that rhubarb is not safe to eat if the leaves have experienced a frost. Leaves damaged by frost are very likely to have leached oxalic acid into the rhubarb stalks. Plus stalks that have experienced freezing temperatures are likely to be extremely soft and have poor flavor.
Rhubarb plants grow from short thick rhizomes. Typically these are available in the very early spring while still dormant. Plant with the crown bud about two inches below the surface, and leave three to four feet of space in all directions between rhubarb plants.
If rhubarb leaves and stalks decrease in number and size, it may be time to divide the plant. Division is best done in the early spring, selecting the most vigorous rhizomes to keep for the new planting.
Leaves emerge from the rhizomes and later in the spring and summer, flower stalks and flowers may develop. It is best to remove the flowers to encourage the plant to put its energy towards producing more foliage and edible stalks. Named cultivars, which typically demand a higher price, have been selected to produce fewer flowers than cheaper unnamed cultivars.
Rhubarb stalks may be red, pink or green or some combination. Most people prefer red and pink colored cultivars, although cultivars with green stalks are much more vigorous plants and yield more. Some claim red and pink cultivars have better flavor than green. I would think that one reason some people might shy away from green stalked varieties is appearance when cooked. Somehow mushy green stalks don't sound as appealing as rosy red ones.
Rhubarb stalks should not be harvested at all the first year plants are in the ground. The second year they may be harvested for a week or two, and the third year they can be picked for eight to ten weeks, a full season. In Illinois, typically rhubarb harvesting begins in mid-June and again in August.
When harvesting, pull or cut the stalks from the plant, being careful not to injure the plant's crown. Do not remove more than one third of the leaves from a plant at one time. Immediately remove the poisonous leaves from the stalk. The stalks should be stored in the refrigerator, unwashed and wrapped tightly in plastic wrap. They should keep for at least three weeks.
I haven't planted rhubarb in my garden yet, but hope to in the future. Even if my husband refuses to eat it, it is a beautiful plant for the landscape. The large leaves and colorful stalks are an attractive addition to the perennial garden. This might be the only way I can convince him we need to plant rhubarb!