Rhubarb: How to Grow it and How to Use it

Rhubarb: How to grow it and how to use it

Rhubarb is a hardy perennial that deserves a permanent place of honor in every kitchen garden. Although technically a vegetable, it is used as a fruit — in pies, cakes, preserves, and other sweet dishes.

By Roy Beck

Rhubarb is a plant that I have been in love with for a long time. This hardy perennial deserves a permanent place of honor in every kitchen garden. Though technically a vegetable, it is used as a fruit — in pies, cakes, preserves and other sweet dishes. Rhubarb is not difficult to grow and enjoy if its needs are met.

Planting Rhubarb

Rhubarb likes to grow in full sun or light shade, in a rich sandy loam soil that drains well. Most rhubarb is propagated by division, not by seed, because the seed is not always true to type.

Some books suggest that the division be planted so that its growing tips (buds) are four to five inches below the surface of the soil. Here in the Pacific Northwest where I live, with all the rain that we get, the plants would rot if they were planted that low in the ground. For this reason, I prefer to mound the soil about six inches high and plant the plants so the buds are just below the soil surface. For those of you who live where it is drier and colder, the plants could be planted lower in the ground.

I plant rhubarb divisions three to four feet apart and water them well after planting. The plants need to be kept moist, but not too wet or too dry. If they dry out, they will go dormant, and if they are over-watered, they will rot.

Rhubarb is a heavy feeder, and I find that composted manure is the best fertilizer for it. Do not use fresh manure as this can burn the plants. Each year, just before winter comes, I fertilize the plant with three to four inches of manure compost. If the plants are fertilized too soon in the fall, they will start to grow again and will not be dormant when winter sets in. Over the winter, the compost will be decomposing and will be broken down by the time you are ready to pick the first rhubarb stalks in the spring.

Rhubarb is a plant that usually does not have much trouble with diseases and pests. I remove and compost dead leaves and stalks because diseases can overwinter in them. I don’t put composted rhubarb plants back on the rhubarb patch.

Harvesting Rhubarb

Only the leaf stalks (petioles), which can be pink or red or even green, can be eaten. Rhubarb leaves are poisonous to humans and livestock and should never be eaten.

For the first year after planting your rhubarb plant, don’t pick any stalks. This will allow the plant to focus its energy on developing a strong root system. The following year, you can harvest some stalks. The plants will come into full production in the third year and continue for many years if properly maintained.

Commercial growers go through the fields and cut off all the stalks each time they pick. I do not think this is the right way to pick rhubarb. Weakening and stressing the plants in this way encourages them to go to seed. Seed production uses up a lot of energy that could be used to grow stalks. As with pruning any plant, one should not remove more than a third of the plant at any given time. If you pick only those stalks that are of mature size and fully-grown and let the others continue growing, you can extend the rhubarb harvest over a longer period.

When the stalks start becoming very thin in diameter, it is time to stop picking. Also, as it gets warmer and later into the season, the rhubarb generally will not be as good to eat because it will get stronger in flavour and will have more fibres. There are, however, varieties in Sweden that have high-quality, low-acid stalks that can be picked all season long.

Rhubarb does not grow well when the temperature rises above 80º F and the soil dries out. But if you keep the plants well watered (not over watered) and do not over-pick the plants, they should keep growing all summer. The big rhubarb leaves are very good at cooling the soil, keeping it moist and shading out weeds. If a mulch is to be used, very well composted manure is the best choice.

Dividing Rhubarb

When the plants are 3 to 4 years old, they can be divided. If rhubarb plants are not divided in about 10 to 15 years, most varieties can lose their vigor and slow down — and possibly die.

It should be divided when it is dormant — before the ground is frozen in the fall or after the ground has thawed in the spring. With a shovel, I remove either the whole crown or part of the crown from the rest of the plant. I then divide it into pieces at least the size of a doubled-up fist. Smaller pieces might grow, but the larger the pieces are, the more energy they will have to get a good start. Smaller pieces take a lot of care, so I start with a large division.

Commercial plant growers dig the divisions when the plants are dormant and store them in a cooler until spring to sell them. In the American northwest, rhubarb can be planted in either spring or fall. If you are in a colder climate you will need to wait until you can work the soil.

Using

After picking the rhubarb, wipe the stalks with a moist cloth to clean them. If you put the stalks into water to wash them, they will split before storage, so just wash prior to use.

Clean rhubarb should be stored in a cool dry place like a refrigerator. If the stalks are fully mature when they are picked, they will keep very well for a couple of days. But if they are picked immature, they will wilt and not be useable.

Rhubarb can also be stored in the freezer and used throughout the year. Cut the stalks into one- or two-inch pieces and put them into airtight freezer containers. Then place the containers in the freezer and enjoy them as needed in your favorite recipes, such as my rhubarb crisp, below.

I have been collecting rhubarb and now have some 90 different varieties. I started to look for plants and found that the books listed a lot of different varieties that were not to be found. So like all the other vegetables, rhubarb varieties are disappearing and need to be saved. I need your help in finding those varieties. I know that there are varieties out there that I do not have in the collection because I have read about them. The variety that you have or see might be one that I do not have and that needs to be saved. Please pass on to me any information that you have about any varieties. If the variety is one that I do not have, I could either buy it or trade with you for one that I have. I hope to be able to keep adding to the collection for many years to come.

Roy Beck’s Rhubarb Crisp

3 cups brown sugar
2 cups all-purpose flour
2 cups old fashioned oats
¾ cup softened margarine or butter
2-¼ pounds chopped rhubarb

In a large bowl, mix the brown sugar, flour, oats, and butter together. Heat oven to 375°F. Use an oval pan, 12″×11″×2″. Make a layer of the sugar, flour, oats, and butter mixture into a crust on the bottom and sides of the pan. After filling the pan with the rhubarb, put the rest of the mixture over the rhubarb. Bake for 40 to 50 minutes or until tender. Serve warm with vanilla ice cream or whipped cream.

Roy Beck grows 90 different varieties of rhubarb. He is interested in saving old varieties from disappearance and invites readers with a similar interest to contact him at broadviewfarm@xplornet.ca. This article was first published in Natural Life Magazine in 1999.