jar of blubarb jam with a spoon in it, surrounded by rhubarb

Blubarb Jam

Excerpted from Preserving with Pomona’s Pectin by Allison Carroll Duffy (Fair Winds Press, June 2013)
Allison says: “The combination of blueberries and rhubarb is less common than the typical strawberry-rhubarb pairing, but it really shouldn’t be—this lovely, deep blue jam is a delicious, tangy treat. This recipe was adapted from one by jam-maker Kirsten Jennings, who first tried it at a local restaurant and liked it so much that she figured out how to make it at home.”


Tip: Frozen Ease!
You can substitute frozen berries for the fresh, and if you don’t have a lot of time, this is a good option. Simply defrost the berries, and then mash them as the recipe calls for. After defrosting, the berries will be in a lot of juice, but don’t drain them—simply incorporate all of the juice into the mashed berries.
Servings 5 cups


  • 1 pound blueberries
  • 1 pound trimmed rhubarb stalks
  • ½ cup water
  • ¼ cup lemon juice bottled
  • 2 teaspoons calcium water see step #1
  • cups sugar
  • teaspoons Pomona’s Pectin mixed with sweetener


  • Before you begin, prepare calcium water.
    To do this, combine ½ teaspoon calcium powder (in the small packet in your box of Pomona’s pectin) with ½ cup water in a small, clear jar with a lid. Shake well.
    Extra calcium water should be stored in the refrigerator for future use.
  • Wash your jars, lids, and bands. Place jars in canner, fill canner 2/3 full with water, bring canner to a rolling boil, and boil jars for 10 minutes to sterilize them. (Add 1 extra minute of sterilizing time for every 1000 feet above sea level.) Reduce heat and allow jars to remain in hot canner water until ready to use. Place lids in water in a small sauce pan, heat to a low simmer, and hold until ready to use.
  • Rinse blueberries, remove stems, and mash in a large bowl. Set aside.
  • Rinse rhubarb, slice stalks lengthwise into thin strips, and then dice. Combine diced rhubarb in a saucepan with the ½ cup (of water. Bring to a boil over high heat, reduce heat, and then simmer, covered, for 5 minutes, or until rhubarb is soft, stirring occasionally. Remove from heat and mash rhubarb.
  • Measure out 2 cups of the mashed blueberries and 2 cups of the mashed rhubarb (saving any extra for another use), and combine the measured quantities in a saucepan. Add lemon juice and the calcium water, and mix well.
  • In a separate bowl, combine sugar and pectin powder. Mix thoroughly and set aside.
  • Bring fruit mixture to a full boil over high heat. Slowly add pectin sugar mixture, stirring constantly. Continue to stir vigorously for 1 to 2 minutes to dissolve pectin while the jam comes back up to a boil. Once the jam returns to a full boil, remove it from the heat.
  • Can Your Jam: Remove jars from canner and ladle jam into hot jars, leaving 1/4 inch of headspace. Remove trapped air bubbles, wipe rims with a damp cloth, put on lids and screw bands, and tighten to fingertip tight. Lower filled jars into canner, ensuring jars are not touching each other and are covered with at least 1 to 2 inches of water. Place lid on canner, return to a rolling boil, and process for 10 minutes. (Add 1 extra minute of processing time for every 1000 feet above sea level). Turn off heat and allow canner to sit untouched for 5 minutes, then remove jars and allow to cool undisturbed for 12 to 24 hours. Confirm that jars have sealed, then store properly.

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13 Responses

  1. Kevin Straub
    | Reply

    at what point in the instructions does the lemon juice, calc. water, and fruit portion get added back and mixed with the main batch?

    • Shelby Collings
      | Reply

      5. Measure out 2 cups of the mashed blueberries and 2 cups of the mashed rhubarb (saving any extra for another use), and combine the measured quantities in a saucepan. Add lemon juice and the calcium water, and mix well.

  2. Wendy
    | Reply

    Can you substitute honey for the sugar?

    • Shelby Collings
      | Reply

      You sure can!

  3. Monica Strohhaecker
    | Reply

    could i adjust the sugar to just 1 cup?

    • Shelby Collings
      | Reply


  4. Kristin Anderson
    | Reply

    Can I substitute blackberries for the blueberries?

    • Shelby Collings
      | Reply

      Yes, you sure can, that sounds delicious!

  5. Jolee Tacheny
    | Reply

    Do you have a recipe for mint jelly besides the one for ‘herb jelly” ?
    I always made it with JureGel but that is unavailable now.

    • Shelby Collings
      | Reply

      Hello Jolee,
      We sure do! HERE is our Mint Jelly recipe, if you prefer sugar over honey you can use 1 cup of sugar to mix with the pectin. Once your jelly has come together, give it a taste and if you need more sugar, you may add it at this time. Stir to combine and remove from heat.

      Happy jamming and welcome to the Pomona’s family!

  6. Nicola
    | Reply

    Really lovely flavour to this. Will be making it again.

  7. Connie Tuttle
    | Reply

    can I substitute fresh peaches for blueberries?

    • Shelby Collings
      | Reply

      You sure can! You may wish to increase the pectin by 1/2 to 1 tsp depending on how juicy your peaches are.

      Happy jamming!

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