Slow Cooker Blueberry Plum Butter

Blueberry Plum Butter | Rosemarried

Canning in the summertime presents a funny conundrum.

On the one hand, this is the best time of year to preserve fruits and vegetables. We are in the peak of summer and farms and gardens are bursting with an amazing array of fruits, vegetables, and herbs. The fields are plentiful. My fridge and pantry are full of the goodness of summer. This is a wonderful time of year.

On the other hand, there is the issue of warm weather and the unbearable temperature of my kitchen. My kitchen is, by far, the hottest room in my house. So let me tell you,
the idea of firing up the ole canning pot on a hot August afternoon sounds ludicrous to me.
When it’s sweltering outside, I would rather not hang out with boiling pots of water and jam.

Thankfully, there is good news. There’s always the option of the slow cooker. Granted, you cannot actually can or preserve using a slow cooker. You must process jars in boiling water, which requires a large pot and a stovetop. There’s just no getting around it. However, you can make your jam or preserves in a slow cooker, which drastically cuts down the amount of stove time. This, in turn, drastically reduces the sweltering temperatures in my kitchen. And, for that, I’m thankful.

This recipe is incredibly simple and yet, it is so rewarding. The blueberry butter is smooth, luscious, and full of the flavors of summer. And through the simple act of canning, I can enjoy these summery flavors all year long.

Slow Cooker Blueberry Plum Butter


  • 10 cups fresh blueberries
  • 4 large black plums
  • 2 cups white sugar
  • Zest and juice of one lemon


  1. Wash and drain blueberries. Remove any stems, leaves, or debris. Cut the plums in quarters and remove the pits.
  2. Using a food processor, puree the blueberries and plums. Process until smooth. (You should end up with 8 cups or so of puree.)
  3. In a slow cooker, cook the fruit puree on high heat for one hour. After one hour, stir the butter and crack the lid for the remainder of the cooking time. (This allows steam & water to escape so the butter reduces and thickens!).
  4. Cook the butter on low heat for 6 (or more) hours. (Note: slow cookers do vary depending on size, brand, etc.) Stir the butter once an hour.
  5. In the final hour of cooking, add the sugar, lemon juice, and lemon zest. Stir well. Turn the heat up to high and continue to cook with the lid slightly ajar.
  6. Meanwhile, prepare your canning jars and lids. Sterilize jars and lids by boiling in hot water for 10 (or more) minutes. Keep the jars in hot water until ready to use.
  7. Once the butter is thick and creamy (similar in thickness and texture to ketchup), it is ready for canning! (Note: I pureed my butter with an immersion blender at this point in the process, because I wanted it to be super smooth. I highly recommend it!)
  8. Remove jars from the canning pot and fill with butter. Wipe the rims with a clean, dry cloth. Seal jars with lids and rings and place back in the canning pot. Bring the water back to a boil and process the jars for 10 minutes.
  9. Remove jars from the canning pot and place on a dry towel or rack to cool. After the jars have cooled, check to ensure that all jars sealed properly. If properly sealed, jars may be kept on the shelf or in your pantry for 6-12 months. (If they did not seal properly, the jars can be stored in the fridge and will keep for a week or two.)


Slightly adapted from Simple Bites

13 Responses

  1. Heather says:

    This is great! We have a plum tree in the backyard that’s dripping with ripe plums that we didn’t know what to do with! Looks like we do now :)

  2. Maria Tadic says:

    This looks super yummy! I love fruit butters – they’re always so good on my morning toast! I’ve never had blueberry butter and it looks so easy to make!

  3. […] stories, snap photos, sample goodies (thanks to Lindsay of Rosemarried for the fresh batch of Slow Cooker Blueberry Jam & just-pulled-from-the-oven scones!), and assemble a story about the PDX Food Swap to air on […]

  4. […] I finally used up the blueberries making a slow cooker blueberry-plum butter recipe I found online at,¬†cutting a bit of the sugar and switching lime for the […]

  5. stephanie says:

    This sounds delightful; however I do not have a slow cooker.
    How would I do this on my stove?
    Also, what is the yield of this recipe?
    Thank you!!

    • lindsay says:

      Hi Stephanie! You could make this on the stovetop, but the cooking time would change greatly. (I would imagine that this would cook on the stove in about 3 hours). The yield was about 6 half pint jars.

  6. […] love being able to toss stuff into a crock-pot and walk away?) and found one at Food In Jars¬† that looked easy […]

  7. Cat says:

    This recipe looks amazing! Can you freeze the butter instead of canning it?


  8. Rylan says:

    Am I blind?? sometimes I am.. Is there a yield mentioned?
    I’ll guess about 8 half-pint jars based on other similar recipes

  9. Kay Weeks says:

    Last fall a jar of my Slow Cooker Blueberry Plum Butter won a blue ribbon at the Georgia National Fair. Thank you for a blue ribbon recipe!

  10. Bella says:

    I made 2 batches of this last summer and loved it! Im currently making a new batch thanks for the great recipe

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