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Vanilla Rhubarb Jam (Small Batch Canning in a Large Batch Pot)

Vanilla rhubarb jam, right out of the canner

Maybe I’m late to the party, but I just realized this morning that I don’t have to fill my big canning pot with an insane amount of water every time I can. I have been trying out various small batch (3-4 jars) canning solutions, but they are all pretty hacked and inelegant. It’s such a downer to make a quick batch of jam only to wait (and wait and wait) for my canner to come to a rolling boil. Yesterday, I bought cute, squat half-pint jars at our local hardware store and realized that they only take about 6 inches of water to cover properly. Hurray! That will boil so much faster than the 12 inches I need for regular half pints!! I can’t believe I didn’t think of this before. I’ve been crafting racks for smaller pots out of everything I could think of, but they all end up floating to the top and upsetting the jars. Seriously, folks… Lesson learned.

The jars were my second awesome find this weekend. The first was a big handful of rhubarb from the Somerville Winter Farmers Market. Rhubarb is a weird thing, but I love it. It’s treated like a fruit, but it’s really a vegetable. It has been cultivated in China for centuries due to its medicinal qualities. Interesting fact and tie in to our recent trip to Hong Kong – In 1839, China threatened to end the rhubarb (and tea) trade if Queen Victoria continued to allow opium into China. The Rhubarb Compendium has more interesting factoids, if you’re interested.

One cautionary note about rhubarb…Although the leaves look like tasty swiss chard, they’re poisonous, so don’t eat them. This is the one time I fully support tossing out the dark leafy green part.

For this jam, I modified a recipe from Canning for a New Generation to fit what I had on hand, namely vanilla beans rather than oranges. Did I break Unbreakable Rule Number 3? No, and here’s why.

  1. The National Center for Home Food Preservation gives a recipe for stewed rhubarb with only sugar and rhubarb. Since the original jam recipe was only rhubarb, oranges, lemons, and sugar, I’m could take out the oranges AND the lemons without compromising acidity.
  2. The vanilla I added was just a tiny bit, so I am assuming that the lemon juice more than offsets any acidity damage. I have also seen similar recipes from trusted online sources (such as Food in Jars)

On to the recipe! This is a simple one. Just a few ingredients and minimal fussing. There’s just enough sugar to be sweet, but not cloying, and the vanilla smooths out the rhubarb’s tartness. Adding the lemon hulls into the jam towards the end ups the pectin, which results in a firmer jam without having to include commercial pectin. Yum yum yum!

Rhubarb + Sugar = Happiness

Vanilla Rhubarb Jam

About 3 half-pint jars

Amount Ingredient Preparation Where we bought it (SWM = Somerville Winter Market)
1 1/2 pounds Rhubarb Enterprise Farm (SWM)
1 Lemon
1/2 Vanilla bean
1 1/2 cups Sugar


  1. Get your canning gear ready. (Steps 3 and 4) There are two special steps this time. First, because the jam doesn’t process for very long, you need to sterilize the jars. Second, put a couple of small plates in the freezer. We’ll use these to test the jam later.
  2. Wash the rhubarb, remove any bad spots, and cut it into 1/2-inch slices. Toss into your favorite pot.
  3. Juice the lemon. Measure out 2 tablespoons of juice and pour into the pot with the rhubarb. Save the hull and seeds, but you can toss any remaining juice.
  4. Cut the vanilla bean in half lengthwise. Use the tip of your knife to scrape out the seeds and drop them into the pot. Save the pod.

    Cutting the vanilla bean in half

  5. Add the sugar to the pot and cook over medium-high heat until enough juices are released to cover the rhubarb. Stir frequently. At first the pot will be totally dry, but it should only take 10 minutes or so.
  6. While the jam is cooking, put the reserved lemon hull, seeds, and vanilla bean pod into a jelly bag. If you don’t have one, you can tie it up in cheesecloth or even a (clean) stocking. You just want the jam to be able to leach out all the goodness without the lemon seeds ruining things.
  7. Once the rhubarb is covered in its juice, turn up the heat, drop in the bag you just made, and bring everything to a strong boil, stirring constantly. Try to keep the mouth of your bag out of the liquid, so that it doesn’t fill up with jam. I either tie it losely to the pot handle or hold it in my non-stirring hand.
  8. After 5 minutes, turn off the heat and grab one of the plates from the freezer. Put a small dollop of jam on the plate and stick it back in the freezer. After a minute or so, take it out and draw a line through the jam with your finger. If it leaves a trail, it’s done. If the line fills in right away, it needs to be cooked more – bring it back to a boil, boil for 3 minutes, and retest.

    Testing the firmness of the jam

  9. Take out the bag and scrape off as much jam as you can. Bring the jam back to a simmer briefly, just to make sure it’s hot enough to can.
  10. Fill your half-pint jars, leaving 1/4 inch headspace, and process for 5 minutes. (Steps 6 through 22)

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