Rhubarb: How to Grow and Harvest

By Guest Author Dayton Kingery

Rhubarb’s deep-red ruby stalks, known as petioles, and massive leaves, bring height and structure to any vegetable or perennial garden. It is a gorgeous plant with stalks that look like red, pink, or green celery, depending on the variety.

As a cold-loving, easy-to-grow perennial, rhubarb is an early bloomer and one of the first veggie harvests of the spring. Botanically, rhubarb is classified as a vegetable, but it’s prepared like a fruit because of its tart and sweet taste. It’s frequently baked into pies, served like applesauce, or canned in jams and jellies.

How to Grow Rhubarb in Your Garden

Tips on planting rhubarb

Rhubarb can be started from seeds indoors during winter or transplanted from crowns bought online or at your local plant nursery. Unlike most vegetables, rhubarb is a perennial. That means once you plant it, it’s going to grow in that area of your garden for many years. So choose a sunny spot where the plants will get at least 6 hours of direct sunlight each day and won’t be disturbed by shady trees or other vegetables. Rhubarb is only hardy in zones 3-8 because it needs a chilly winter with temps consistently below 40 degrees to produce a sweet crop.

To prepare the soil before planting, dig a hole 2 feet wide and 2 feet deep to give the roots plenty of room to spread. Rhubarb prefers a loamy soil that drains well, and it won’t tolerate a waterlogged soil. If you garden where the soil is mostly clay, add compost or peat moss to the soil at planting time and top dress the plant each year with more compost.

Allow 3-feet between plants, but most gardens will only need one plant, as rhubarb produces a plentiful harvest after the first few years. Nonetheless, space the plant 3-feet from its neighbors, as this vegetable spreads vigorously. You needn’t be too concerned about the soil pH as rhubarb is not fussy and will grow nearly anywhere. But for optimum performance, it helps to have a soil slightly on the acidic side.

Caring for Rhubarb

Rhubarb is a large and thirsty plant and in order to reach such substantial growth it needs plenty of nutrients, water, and organic matter. In early spring, add a high nitrogen organic fertilizer to encourage top growth and compost to nourish the crown and roots.

Weekly during the growing season, provide at least 1-inch of water in the absence of rainfall. Insufficient moisture and/or consistent early season heat will cause the rhubarb to become distressed or even bolt, yielding a bitter and inedible harvest. The plants can be encouraged to retain their moisture with a layer of mulch at the base of the plant. When the plant produces flower stalks, remove them as soon as possible as they are an indication of bolting; you want to prevent the plant from hastily setting seed and reproducing.

Rhubarb has very few pest problems

Rhubarb is a hardy plant and stands up well against most garden pests. While slugs and snails might feed on the leaves, the plant typically endures. The best way to keep pests away from rhubarb is to keep the area around the plant free of weeds. 

Harvesting Your Rhubarb Crop

As with Asparagus, allow rhubarb to grow undisturbed for the first 2 seasons before harvesting. In the 3rd year, harvest the stalks for only 3-4 weeks. After the 4th year and thereafter you can harvest stalks for 6-10 weeks. But never harvest more than 2/3rds of the plant or it won’t be able to produce enough top growth and stalks the following season.

Stalks (known as petioles) are ready when they are 10-15 inches long, starting in late winter through late spring. When deciding which rhubarb stalks to harvest, choose those that are firm and crisp. Stalks that are soft, limp, or seem damaged should be removed but not consumed. It isn’t necessary to take the whole crop at once, as the stalks can be cut as you need them. 

The safest method of harvest is by hand: grasp the stalk just below the leaf and pull upwards and to one side. It should snap off. Never cut stalks from the base of the plant as you need to leave about 1/3rd of each stalk to maintain plant health. Additionally, don’t use tools to harvest, as they are notorious for spreading disease. Tools may also encourage you to cut the stalks too close to the base, exposing plant tissue to potential disease. Immediately after harvesting, remove the leaves from the stalks, as these are inedible. Read more about Rhubarb from Utah State University.

Rhubarb can be “forced” to harvest early, producing a paler, sweeter, and less crisp vegetable. Rhubarb plants covered with forcing jars or buckets in late winter will form stalks without any exposure to the sun. This crop can be harvested in early March, weeks ahead of the typical spring harvest. 

How to prepare and use Rhubarb

Warning: Never eat the leaves of Rhubarb, only the stems. The greens contain oxalic acid – a substance poisonous to humans if consumed in quantity. The thick stems—red, pink, or green—is the part that is meant to be eaten. See more from Oregon State University.

Since the rhubarb growing season is so short, and the crop is so plentiful, freezing rhubarb is a great way to preserve the freshness and flavor for a few months. It can also be stored in the refrigerator for 2-4 weeks. Before freezing or cooking fresh rhubarb, wash the stalks carefully to get rid of any grit or dirt. If you want to keep the rhubarb’s bright color, blanch the stalks before freezing. 

The flavor of the rhubarb depends on the particular cultivar: Canada Red generally produces short, lean stalks that are sweet; Cherry Red has long, juicy petioles; Victoria is a spotted green and red rhubarb with strong flavor. Rhubarb is too tart to be enjoyed raw and is usually cooked before it’s eaten. But if you do want to eat raw rhubarb, you should first dip it in sugar or sweet syrup. It can be baked in a pie, boiled in a jam, or blended in a cold drink or smoothie. 

Author’s Bio: Ever since hiking through Connecticut’s portion of the Appalachian Trail as a young boy, Dayton Kingery has been passionate about hikes, plants, gardens and all things related to nature. His passion was fueled by living in a state with so many wonderful national parks, trails, and gardens. Dayton is the founder of BusyBodies365 which is dedicated to the pursuit of a healthy and active lifestyle.

We garden in Pennsylvania, United States, zone 6B. Much of the info we share is based on gardening in our temperate area. But many of the flowers, vegetables, and fruit we write about can be grown in soil other than ours (clay) and significantly different weather conditions and elevations. You might need to choose specific varieties for your region, modify your garden, add soil amendments, or adjust the soil pH to match our results. Please check your local university extension website for specifics for your area.