Rhubarb is a staple of the Manitoba garden and beloved in pies, cobblers and muffins throughout the year.
Though it thrives in our cool climate, it’s not native to our soil. Rhubarb is native to central Asia, according to an article from the University of Minnesota, where it was valued for its medicinal qualities. Marco Polo observed it when he travelled to China in 1271, but it wasn’t brought to Europe until the East Indian trade began.
It’s said that Benjamin Franklin introduced it to the Americas in 1770 when he sent a case of rhubarb root from London to his friend John Bartram. The British experimented with varieties of the plants, according to the University of Minnesota, and this eventually produced the tasty cooking varieties we know today.
It first appeared in American seed catalogues in 1829, and has been a garden staple ever since.
Getty Stewart is a professional home economist, speaker, recipe developer and author from Winnipeg. She’s the author of cookbook Rhubarb: Sweet & Savory Recipes and Preserves. She spoke to the Co-operator to answer rhubarb questions. Her answers have been edited for length and clarity.
How can gardeners ensure their rhubarb thrives?
Once rhubarb is established it does really well and it’s quite drought tolerant. It needs the cold and frost and freezing in order to thrive, and so we’re quite lucky that we have the perfect growing conditions for rhubarb.
That said, starting rhubarb can be a little bit tricky. When it’s young and you’re just trying to get it going—so for the first two, maybe three years—it doesn’t tolerate drought very well so you do have to keep it watered and you do have to nurture it a little bit more.
It does like some good compost. I usually do that when I’m putting it to sleep in the winter. I will add some compost around the base of it just before the snow flies. Or I’ll do it early in the spring. If you don’t have compost, then a little all-purpose fertilizer or bone meal will do the trick as well.
Rhubarb does prefer to be split every five to ten years. So if you’ve had a rhubarb plant that is like ‘oh my gosh, I had this when my grandmother was around’ and you’ve never divided it, then it’s actually a good maintenance thing to split and divide your rhubarb at least every ten years so that it revives the root. What you’ll find is that you’ll get more tender stocks. The seed head that comes out, it won’t bolt quite as quickly.
It’s usually best to do… once the ground is workable and the rhubarb hasn’t quite shot out of the ground. What you want is one to three shoots coming up or starting to form just below the surface. Dig a hole around your rhubarb plant. Once you move the soil, you’ll see that there’s these new shoots starting to form. So you want at least two or three of those shoots in every new planting that you have. And you take a spade and just slice the root right through the thick woody part of the root.
You don’t want to put the shoot too deep. You only want to cover it with about an inch of soil, but you do want to have the root be able to establish itself. So you want to dig a nice hole way too big for the size of the root that you have, but it loosens the soil and really give it a good ability to grow without having to force its way through, especially clay soil.
You want to plan for a good square meter around the shoots, and you probably want to put two to three clumpings of roots together in the one hole. And then a little bit of fertilizer or compost or bone meal, making sure to remove all weeds.
Once it’s developed and a tree grows beside it, your rhubarb will continue to go, but when you’re starting a new plant it really does prefer the sun, and it needs good watering.
You can’t harvest it in the first couple of years. It needs all the energy it can get from the stems that do grow. So it will look like you should be able to harvest it. But it really needs those leaves to capture the sun’s energy and to bring nutrients down to the roots.
(You can still harvest from the big, original plant, Getty explains—unless it appears to be struggling).
When is the best time to harvest rhubarb?
Ideally, the best time to harvest is before the seed stalks come out. So when the stalks are about seven inches long and before the seed stalk. Normally end of May to June is when ideal harvest time is for rhubarb.
When people see the [seed stalks] starting to grow on their rhubarb if they want to prolong their rhubarb harvest they should cut that stalk off. Then the rhubarb will continue to be a little bit more tender and they’ll be able to harvest more of it.
You can pick through the summer and you can pick in the fall, but you want to reduce the amount that you pick. On a well-established plant in June, you can pick up to two thirds of the stalks. IN the summer and in the fall, you would only harvest one third of the stalks and leave two thirds of the plant ‘cause it needs more of the greens to really keep itself nourished and strong.
Should you cut your rhubarb or yank it out?
You can do both. If you break off the bottom it’s no better or no worse than cutting it, but if you reach down and tug right at the ground level and get the whole stalk separated from the plant, that is a little bit better for the plant to recover more quickly.
It’s best to pull, but it’s okay to cut.
Is rhubarb nutritious?
There are certain nutrients in rhubarb, so you will get some vitamin C, vitamin A, vitamin K. There’s definitely fiber. There’s some calcium and potassium that we may not get from other vegetables, and rhubarb is technically a vegetable.
But when you think about how we usually use rhubarb—like it’s usually in sweet baking, right? You’re getting some vitamin K, some vitamin A, some vitamin C. Does that make that rhubarb muffin health and nutritious? Well… there’s a lot of sugar, a lot of fat, but sure. It’s a vegetable so we must be doing something good. Certainly, everything in moderation and balance.
(She adds that because of the vitamin K and potassium, people with kidney issues may want to talk to their doctor about eating rhubarb).
Are the leaves really poisonous?
Yes. We should not be eating, we should not be sautéing, using in salads or anything like that. It has higher oxalic acid in the leaf, so we should not eat those. Now, it would take a lot of leaves for you to become extremely sick from eating rhubarb leaves. And they’re just not that tasty and you’d get sores in your mouth before you reach critical levels.
I think there’s rumours that maybe in World War One, because people were starving, somebody may have passed away from eating rhubarb leaves, but as far as I know there have been no reported cases of rhubarb poisoning as cause of death.
If we have, for example a late frost, and rhubarb gets damaged… (she gives the example of a freak snowstorm or cold snap in late May)… so the leaves turn limp, the stems turn limp and it just doesn’t look good. You should not eat the stalks. You should not eat any of that rhubarb at all. Not until there’s new growth that looks fresh and good and healthy. Those oxalates that are in the leaves will move down to the stem, so hard-hit, frost-bitten rhubarb is not safe to eat. If the stalks look bad, don’t eat it.
What is your favourite way to prepare rhubarb?
That changes through the season. The first batch, I love stewed rhubarb and then rhubarb pie and then rhubarb crisp and rhubarb cobbler. Some of the classics are some of the first things I would have. And then, toward the end of the season I’m turning it into barbecue sauce or making juice out of it and making rhubarb lemonade and really fun and interesting recipes.
What are some unexpected ways to use rhubarb?
We don’t think of rhubarb as being juicy, but if you boil it down and squeeze out the juice, it makes great cocktails or ‘mocktails’. You can make lemonade. You can make a breakfast mimosa with a little bit of champagne and orange juice in it.
Last summer I made, I call it “nice cream” with an ‘n’ because it’s mashed bananas and rhubarb basically and you freeze it and you make this delicious dessert with it. I make a focaccia bread with caramelized onions and slightly braised rhubarb. It’s quite nice. I also dehydrate rhubarb into little pieces which I then add into different tea blends.
You can find Getty’s rhubarb cookbook and other recipes at her website gettystewart.com.