When I think of rhubarb, I always think of my grandmother. Like many gardeners of her time, she grew this large, old-fashioned, perennial vegetable in a sunny corner of the garden. The leaves, which are poisonous, were discarded, but she cut the tender, red stalks to use in pies, jams, and syrups, usually combined with strawberries. As a child, I loved to eat the raw rhubarb stalks. Grandma would cut a few stalks for me and my siblings and send us outside with a cup of sugar. Rhubarb is very acidic and causes a pucker like few other foods, but dipped in sugar, its sweet crunch is addictive.
Even if you think you don’t like rhubarb, it’s worth growing one plant. Rhubarb doesn’t take up a lot of room, and it needs even less maintenance. It serves as an inexpensive filler in berry jams, where it is almost indistinguishable. Some people even make wine from rhubarb. You might find you like it so much that one plant isn’t enough, in which case, rhubarb is easily propagated through division.
Because rhubarb is a perennial vegetable plant, you’ll want to plant it in a back corner of your garden where it won’t be damaged by yearly tilling. Rhubarb needs full sun and deep, well-draining soil. The plant grows three feet tall and wide, with equally large roots, so set aside plenty of room for it. Dig in several shovelfuls of manure and till to a depth of at least eight inches. Rhubarb grows best in slightly acidic soil with a pH level between 5.5 and 6.5. Add moistened peat moss, pine needles, or dried leaves to very alkaline soil.
Rhubarb is generally grown from divisions, but seeds are also available. If you’re lucky enough to have a neighbor with a plant, you can probably take a small start and save yourself some time establishing your plant. Otherwise, buy rhubarb seeds or starts from a nursery or reputable mail-order service.
Plant rhubarb in early spring, as soon as the garden can be worked. Make a trench two feet wide and six inches deep and mix a bit of compost or manure in the bottom of the hole. Place the plant in the hole with its roots spread out. Situate the plant so its crown, which is the area where the roots meet the plant, sits two inches beneath the soil. Gently firm the soil around the roots and water it in well.
Mulch the rhubarb plant with grass clippings or straw and water it at least weekly to keep the soil evenly moist, but not soggy. Poorly draining conditions promote rot. Fertilize rhubarb each spring with a few shovelfuls of manure or a balanced fertilizer.
Like asparagus, rhubarb needs a few years to become established. Don’t pick any stalks the first year, but allow the stalks to develop leaves, which will fuel strong root growth. The second year, you can harvest a few stalks that grow at least one inch thick. In the third year, you can harvest a few more. From the fourth year on, harvest as many stalks as you like, but stop when the stalks become thin. To harvest rhubarb stalks, you can cut them with a knife or twist and yank them.
In midsummer, you’ll notice tall, thick, leafless stalks growing in the middle of your rhubarb patch. These stalks produce white flowers and seeds. From year one, cut these stalks back to the ground before they flower. If allowed to flower, the plant will produce fewer edible stalks. In some cases, the plant might stop producing stalks altogether.
Pests and Disease
Rhubarb suffers from few pests or diseases, but rusty snout beetles cause black spots on the lower portions of the plants. These beetles can be picked off by hand. Rot, caused by damp, shady conditions, is the most common disease to afflict rhubarb. If you notice wilting leaves and blackened or brown roots, dig up the plant and burn it, because there is no cure. Plant future rhubarb crops in a different location. If your soil is very heavy or soggy, try growing rhubarb in a raised bed.
Sometimes the bottom leaves become wilted or brown, but this is usually not a sign of disease. Simply remove the leaves and discard them.
Rhubarb plants grow quickly to their mature size and will benefit from division every three to four years. Left untended, they become unproductive and overgrown after a few years. To divide rhubarb, use a sharp spade to cut through the middle of the plant. Separate the pieces into one or two large divisions or several smaller ones. Replant the divisions, share them with a neighbor, or discard them in the compost heap if you can’t find a space for more rhubarb. (And yes, it is safe to compost rhubarb leaves. Oxalic acid, the toxin present in the leaves, will not affect the microbes in your compost pile, nor will it harm or be absorbed by the plants you later grown in the compost.)
Visit an online nursery and you’ll find several rhubarb varieties. Your local nursery probably carries only one or two. Victoria is an old-fashioned, vigorous plant that produces green stems instead of red. Most people, myself included, prefer the red varieties for their color and tenderness. Common red varieties include Ruby and Valentine, the latter of which is resistant to rot.
Most rhubarb varieties perform best in cool climates and need a winter freezing to break dormancy. A few varieties, including Cherry and Giant Cherry, are suited to milder climates, although even these types probably won’t grow very well south of USDA plant hardiness zone 7 or 8.
Rhubarb is technically a vegetable, but because it is so tart, it is almost always prepared with sugar and used as a fruit. Steaming is one of the simplest ways to prepare rhubarb. Wash and dice the rhubarb stalks and place it in a saucepan with ½ inch water. Cook over medium heat until the rhubarb becomes soft. Add sugar to taste and cook an additional five minutes to melt the sugar.
Rhubarb also freezes well for later use. Select tender stalks in early spring for best texture. To dry pack rhubarb, dice it and place it in plastic freezer bags. Label and freeze. You can also freeze rhubarb with sugar. Combine one part sugar with four parts diced rhubarb and place the rhubarb in freezer bags. Allow the product to sit for five minutes so the sugar dissolves before freezing.
Remember, don’t eat the leaves of this plant! They’re considered toxic.
Below is a recipe I’ve used for years for strawberry rhubarb jam adapted from the Ball Blue Book Guide to Home Canning, Freezing & Dehydration.
Strawberry Rhubarb Jam
- 4 cups crushed strawberries
- 4 stalks diced rhubarb
- ¼ cup lemon juice
- 1 package powdered pectin
- 5 cups sugar
Mix the strawberries, rhubarb, lemon juice and pectin in a large pot and bring to a boil over high heat. Add the sugar all at once and stir to dissolve. Bring back to a boil and boil hard for one minute, stirring constantly. Skim the foam and pour into prepared jars, leaving ¼ inch headspace. Process ten minutes in a boiling water bath or freeze.