Blueberry-Plum Butter (in the slow-cooker)

Each visit to the market in August finds me with 4-5 pints of blueberries in my basket. I always have high ambitions for jam or pie, muffins or cake, and yet invariably, we always gobble them up in enormous handfuls (and the occasional smoothie) before I can work them into a recipe.

Last week, I had a busy day, but was determined to preserve some of their blueberry goodness in jars before the short season was over. With three kids at home and two separate meetings to attend, my day felt too busy for jam or pie. Fortunately I had a recipe for slow-cooker blueberry butter bookmarked in Marisa’s Food in Jars cookbook, and knew it would be something I could accomplish while highly distracted.

Puree fruit. Simmer in the slow-cooker for the day. Process it in jars in the evening. That’s exactly what I did.The next morning when I cracked open a jar and dipped a spoon inside, I just knew I needed to share the recipe.

This fruit butter receives high scores for simplicity, and is full on delicious; it’s hard to imagine a nicer way to start the morning.

Most days I’ll reach for a fruit butter over a jam for my morning toast, because, well, the fruit (rather than sugar) is the star. Thanks to a long slow cooking time, fruit butters offer an intense flavor and smooth, spreadable texture.

Also, a lot of the water is evaporated out during the simmering process and the natural sugars are concentrated, which means we don’t need to add as much sweetener.

The slow-cooker, as opposed to a heavy-bottomed pot, just means that you can step a little further away from the kitchen, if need be. And believe me, when you’ve got to chase down two boys and scrub their faces for dinner, you don’t want to have to worry about a bubbling pot on the stove.

Where did the plums come in? I was short on blueberries and had four purple plums going soft in my fruit bowl. It seemed like a logical pairing to me and I’ve always been a fan of mixed fruit jams and butters.

Lastly, if you’ve never canned before, don’t let that stop you from making this butter. It will keep for up to two weeks in the refrigerator, or up to 6 months in the freezer. If freezing, be sure to leave a good half-inch of head space at the top of your jars for expansion.

This recipe is adapted from Food in Jars: Preserving in Small Batches Year-Round by Marisa McClellan. In her original recipe, Marisa uses only blueberries (8 cups of puree) and spices things up with cinnamon and nutmeg. I tend to over do the spices, and decided to forgo them this time and let the flavor of the blueberry – and plum – shine through. Lastly, Marisa uses white sugar, but I was very happy with how the spread turned out with organic golden cane sugar as a sweetener.

Update: Here’s Marisa’s original recipe, over on the Food in Jars blog, should you prefer the spiced version.

Slow-Cooker Blueberry-Plum Butter

This Blueberry-Plum Butter receives high scores for simplicity, intense flavour, and thick, yet spreadable consistency.
5 from 1 vote
Print Pin Rate
Course: Preserves
Servings: 6 half-pint jars
Calories: 472kcal
Author: Aimee


  • 5 pints blueberries
  • 4 large plums
  • 2 cups organic golden cane sugar
  • 1 zest and juice of one organic lemon


  • Spread blueberries on a tray or baking sheet and check over quickly for large stems, leaves or bugs.
  • Wash blueberries and plums and drain well. Cut plums in half and remove pit.
  • Combine fruit in a food processor and blend until it is a smooth puree. You should have about 8 cups of puree.
  • Add puree to a slow-cooker, cover and turn to high. After one hour (set a timer!), stir the butter and leave the lid open a crack for the remainder of the cooking time. This will allow for the steam to escape and the butter to reduce and thicken.
  • Cook the butter for 4-5 hours on high or 6-8 on low. Times WILL vary with different slow-cooker brands. Be sure to stir the fruit butter once an hour or so.
  • In the final hour of cooking, add the sugar, lemon zest, and lemon juice. Stir well, and bring to prepare your jars and water bath for canning.
  • Fill a canning pot with 6 half-pint jars or 3-pint jars. Bring to a boil and boil for 10 minutes to sterilize the jars.
  • Place rings and lids in a small sauce pot, cover with water, and bring to a simmer.
  • Once blueberry butter is the consistency of ketchup, it is ready to can.If you want it super smooth, like baby food, you can puree it again with an immersion blender. If not, your butter is ready to can.
  • Working with one jar at a time, remove jars from canner and fill with butter. Wipe the rims with a clean cloth, place a lid and a ring on the top, and return to the canner.
  • Bring canner back up to a boil and process jars for 10 minutes. Carefully remove jars and allow to cool on the counter overnight.
  • Check that all the jars have sealed, then store in a cool place for up to 6 months.


~You can use a blender, Vitamix, or food processor to purée your blueberries.
~I used organic golden cane sugar for this recipe, but white sugar can certainly be substituted. And I'd love to try it with maple syrup.
~Slow-cookers may vary. Marisa recommends cooking the butter for up to 8 hours on low, but I had mine on high the whole time (5 hours) and had no scorching.


Calories: 472kcal | Carbohydrates: 131g | Protein: 3g | Fat: 1g | Saturated Fat: 1g | Sodium: 4mg | Potassium: 420mg | Fiber: 11g | Sugar: 111g | Vitamin A: 365IU | Vitamin C: 52mg | Calcium: 31mg | Iron: 1.3mg

 More Fruit Butter Recipes:

Do you use your slow-cooker for jam, jelly or butters?

About Aimee

Cooking has always been Aimée's preferred recreational activity, creative outlet, and source of relaxation. After nearly ten years in the professional cooking industry, she went from restaurant to RSS by trading her tongs and clogs for cookie cutters and a laptop, serving as editor here at Simple Bites. Her first book, Brown Eggs and Jam Jars - Family Recipes from the Kitchen of Simple Bites, was published in February 2015.

Subscribe For Free!

Like reading this post?
Get more delivered to your email inbox.


  1. I have absolutely never thought to use my slow cooker for jam or butters, what a great idea! And it would definitely be a little easier with the heat than standing over the stove. This recipe looks delicious too. Our wild Maine blueberries are in season right now, and I think they would be perfect for this!

  2. Thanks for adding that it can be frozen for up to 6 months. That makes me much more likely to actually make this very yummy looking recipe.

  3. i sure wish we had blueberries in turkey. this recipe looks yummy. is there any way to make butters/jams without any sugar?

    • Sure! You can leave the sweetener out of fruit butter, just expect that it will be tangy. I pair some fruits with natural sweeteners like honey/pears and maple/apples. That’s another way to avoid white sugar.

  4. Amber | Bluebonnets & Brownies says

    Aimee, you know my feelings on blueberries, but I think you saved it for me with the addition of plums. It looks simply beautiful though, and I can appreciate it visually even if I’m dubious of the flavor. (I’m not a blueberry fan!) I agree with you on fruit butters. I love how they spread, and they’re SO simple to make!

  5. How much butter do you use? Did you forget to list it as one of the ingredients? One more question: Step #5 says to “cook the butter”…do you mean cook the butter and the blueberry puree.
    Sorry to be such a pain. Hope to hear from you soon as it sounds like an amazing recipe that I would like to try.

    • No actual butter in the recipe! When I say cook the butter, I mean the fruit butter…the puree as it heats and begins to cook. Make sense? I hope you try it!

  6. this looks incredible Aimee!! I’ve never made jam, and I think this needs to be my first!

  7. I always use my slow cooker for fruit butters – I’ll often start my apple butter before I go to bed and do a low, slow, no-stir butter that gets pureed when I wake up in the morning. Love the hands-off results!

  8. I love fruit butters and this looks divine; I haven’t yet combined blueberries and plums and after seeing your lovely photos it’s now on my list to do this summer!

  9. I just ordered Marisa’s cookbook – we are giving away one as well – and can’t wait to try this recipe! Time to get the slow cooker out of the pantry! Thanks for sharing!

  10. I have been wanting to go blueberry picking still, and have not made it. Now I really need to, this looks absolutely amazing, beautiful, delicious, and I want it! I love fruit butters, and the concentration of flavors, thank you for sharing this recipe!

  11. Love this! I wish blueberry season wasn’t over around here. And that I had a slow cooker. I’ll be pinning this for next year!

    This is the type of recipe I’d love to see at our Eat Make Grow Blog Hop:

  12. This sounds wonderful, and easy! I’m going to try it.

  13. I was just thumbing through that book the other day wondering if I should add it to my alarmingly huge pile of books I wanted to purchase. Adding it to my wish list!

    That butter looks amazing, I’ve only ever done apple butter before but now I’ll have to get the crock pot out to give this combo a try

  14. I hoped you would share this recipe after readin about your day last week! How do you think honey would do as a substitute for the sugar (forgive me if it’s already been asked)? I’m super sensitive to cane sugar.

  15. I love to make fruit butters, but haven’t done one with my slow cooker. What a genius idea!! I’m definitely trying it with your recipe, since I’ve got a lot of blueberries on my bushes right now. And thanks so much for mentioning my Maple Honey Pumpkin Butter!

  16. This looks delicious! I’m always looking for ways to make breakfast more interesting for the kids! I like that you use golden cane sugar instead.

    Thank you!

  17. Good Food Good Friends says

    This looks so yummy. I cant wait to try this and smear it on some biscuits!

  18. sharron orcutt says

    this year i’ve made mostly butters. love my crock for that. used to use the oven with good results. but since i make smaller batches the crock is great. can’t wait to try the maple honey pumpkin butter. my friends get gift bags of my treats.

  19. Blueberry,Strawberry,banana and honey. I love them all. One of my favorite things to do is make coffee and muffin with strawberry jam. Its probably one of my favorite snacks. 🙂

  20. Any recommendations for making a smaller batch, maybe only one pint? I just keep jams in the fridge, not actually canning them, and we’re short on freezer space (thanks to all the berries in there).
    We have two sizes of slow cooker, so the smaller seems like a better choice for this, but would you recommend any changes to the cook times, or should I just keep a closer eye on it?

  21. This looks absolutely divine… I love fruit butters! I was just dreaming of some homemade apple butter earlier today because we have started receiving some apples in our CSA share already!

  22. Aimee, I too was hoping you’d share the recipe after last week’s post. Every summer we spend a morning on our backyard mountain with rakes and pick 10 gallons of wild blueberries. I was thrilled to see this rendition of fruit butter in a slow cooker. Can’t wait to try it . . . plus peaches . . . apples . . . pears . . . the list goes on. And yes, I may try using our home made maple syrup. We’ve got a few gallons put away.

  23. I made this with wild Newfoundland blueberries, and a combination of raw sugar, maple sugar, and a splash of dark maple syrup. I have been making jams, etc, for 25+ years and this was simply the best product in all that time.

  24. 5 stars
    As a first time jam-maker, this recipe was perfect! I had peaches going soft in my house so I used those instead of plums and it’s deee-licious. It was super easy in my slow cooker. I’m going to try the pear-rhubarb one next. Fruit butter: my new favourite thing! Thanks!

  25. hi,
    love this! I want to try it but is there another fruit, besides plums that doesn’t have a pit, that I could substitute for? my daugther is allergic.


    • Is she allergic to all stone fruits? Or just plums? You can make the recipe ALL blueberries, if you like. There’s a link to a recipe for that in the post, just above the printable recipe.

  26. Hi,
    Just wanted to say I love your blog. I found you by accident!
    Making this jam and I have natural demerara sugar. It is golden and claims to have a “bold, rich flavor.” do you think this would be a good sub for white sugar? Maybe more intersting tasting?

    Thanks, aisha

  27. Quick question: just came back from a PYO Guatemalan blueberry farm and am thinking about making this butter. I don’t have plums, but how would a mango be? Also, what about doing this in the oven on low heat, like granola, and topping the pan with foil?

  28. christina mil says

    We just picked blueberries yesterday, and I happen to have some plums, so obviously going to try this, but I have a few questions. First, about how many cups is 5 pints of the blueberries? Second, I’m confused on how to store. Once made do I store in a cool, dry place, or do I have to refrigerate/freeze? I want to give as gifts, but if they have to immediately be refrigerated I don’t know if that will work. I was thinking that had to be refrigerated/frozen once opened? Thanks so much! Can’t wait to try this!

    • Aimee @ Simple Bites says

      All good questions, Christina. A pint is two cups, and it is also the standard square basket or plastic container of berries. If you buy them from the store, it will most likely say ‘pint’ on it.

      The recipe above includes directions for canning in a hot water bath, and once this is done and the jars are cooled, there is no need to freeze/refrigerate. Your butter is good for a year. Happy jammin’!

  29. I have never made any types of butters before but after reading this recipe, I can’t wait!! We have a plum tree and recently picked a big bowl full. If I were to substitute more plums for blueberries (making sure I still ended up with about 8 cups of puree), do you still think it would be just as tasty? Our plums are smaller than those you would purchase at the store, so I’m not sure how much to substitute for either. About how many plums do you think would be equal to a pint of blueberries? Thanks so much!

    • I think it would be good! You may want to increase the amount of sweetener, though, as plums are much more tart.

      • Thanks! I’m going to give it a try this weekend and try the blackberries instead of blueberries! We just picked a bunch more last night!

  30. Another question! How would it be with blackberries. I know a bit seedy but we recently picked a large amount of blackberries and I would love to do something with them!

  31. Pam from Minneapolis says

    I have great maple syrup and wonder how much you would add in place of sugar. I am never sure how to substitute honey, maple syrup to compensate for the liquid. Do you have any helpful hints? thanks so much!

  32. This butter looks amazing! I can’t wait to get it going but would like to use honey instead of sugar. Would I use the same amount as for sugar?

Speak Your Mind

Recipe Rating