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Rhubarb Means Spring!

canning rhubarb

Rhubarb is a delicious spring vegetable that has some very unusual qualities.

When its not in season, you can sometimes find it in the frozen section of the supermarket. If you don’t grow it yourself, be sure to grab some when you can.

In this post, I answer the following…

  • What is it exactly? (Don’t believe what the government tells you)
  • What’s the pH level? (Can we really water bath process it?)
  • What’s my favorite recipe for using it up? (Trust me, it’s delicious!)

preserving rhubarb

I love rhubarb, but I don’t grow it myself.

Why? Because it tends to take up quite a bit of real estate in my tiny homestead. Plus, I found that with my warm winters, I do not have the chill factor needed to give it a good depth of flavor. So, I rely on my local farmers to provide it OR I use frozen.

However, up north we grow it at the 1892 farmstead with great results. We have two right now: ‘Valentine’ and ‘Giant Cherry’. Both are beautiful in the garden setting.

So Is Rhubarb a Vegetable or Fruit?

A lot people ask this. Traditionally rhubarb is used in pie and desserts and not too many veggies do THAT.

But even though rhubarb is used for its “fruit like” qualities it is not a fruit. Botanically speaking, it is 100% vegetable.

It has a tangy, bitter taste on its own and requires quite a bit of sugar to bring out its delicious nuances. We are consuming the leafstalk (just as we do with celery) and it has none of the botanical requirements for being a fruit.

AND just to confuse matters, the U.S. Customs Court classified rhubarb as a fruit in order to get lower import duties on it. But don’t let that confuse you.  Scientifically, rhubarb is a vegetable through and through.

rhubarb syrupCan We Water Bath Can Rhubarb?

As a canner, you probably hear over and over that you should never water bath process a vegetable that is not “pickled” or you run the risk of botulism. And if you follow me at all, you know I say this all the time.

So what about rhubarb? People can it as jam, jelly, pie filling ALL the time. Why is that?

Here’s the deal:

The thing that determines if you can or cannot water bath ANYTHING is the pH of that food. That is the bottom line.

In most cases, vegetables fall into the pH level of a low acid food and they cannot be water bath processed unless they are pickled or placed in vinegar so that their pH is safe. In other words, most veggies cannot be water bath canned.

But rhubarb is a special case.

Rhubarb is the only vegetable I know of that is treated as a fruit, has “fruit-like” qualities AND has a pH in the “safe zone” (just like a fruit). I guess rhubarb SO wants to be a fruit, it even has the pH of a fruit!

So the bottom line is that with a pH of 3.1, rhubarb can be safely water bath canned. Lucky us!

Also note that most canned rhubarb recipes also include lemon juice in the recipe. This is for two reasons: First as added security for keeping the acidity in the safe zone and second, to add brightness to the flavor. A little lemon will add zing to balance the sugar needed to offset the rhubarb tang.

Is Rhubarb Toxic?

Well… yes.

But only the LEAVES are toxic because they have very high levels of oxalic acid. Unless you have a very high sensitivity to oxalic acid, the stalks of rhubarb are perfectly safe to eat. This is why you always see the leaves cut off the stalks at the super market. If you grow them yourself, don’t eat the leaves! Only eat the stalk.

Preserving Rhubarb

There are lots of ways to put up rhubarb. You can make a jam, pie filling or combine it with other fruits such as strawberries to create something unique. Keep in mind that rhubarb is not high in pectin, so most jam recipes combine with other fruit (like strawberries) or include a commercial pectin to get the gel.

But by far, my favorite thing to do with rhubarb is make a simple syrup.

Yep. It is fast, easy and makes the most incredible syrup EVER. I use the syrup in cocktails, sweet ice tea and I drizzle it over ice cream or other desserts. It is pure heaven in a bottle, I swear.

Here is a link to my rhubarb syrup recipe (with video!) over at my canning blog for our TV show.

Rhubarb Syrup Recipe


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About the Author:

Theresa Loe is the founder of Living Homegrown® and the Canning Academy®. For 9 years, Theresa was the Co-Executive Producer & Canning Expert on the national PBS gardening series, Growing A Greener World®. Theresa homesteads on just 1/10th of an acre in Los Angeles with her husband, two sons and several disorderly but totally adorable chickens. Learn more about Living Homegrown here and about the Canning Academy here.