jars of blackberry jam with fresh blackberries in front

Seedless Wild Blackberry Jam


5 from 1 vote
Seedless Wild Blackberry Jam is a low-sugar cooked jam made with Pomona’s Universal Pectin. Pomona’s Pectin contains no sugar or preservatives and jells reliably with low amounts of any sweetener. This recipe was created by Allison Carroll Duffy for Pomona’s Pectin. She says: Making seedless jam from wild berries isn’t hard to do, but it does take a little time and persistence . . . the results are absolutely worth it. You’ll be rewarded with a luscious, smooth, spreadable jam.


Many wild blackberries are quite sour, but if you are using the sweeter wild blackberries found on the West Coast, add 2 Tablespoons lemon juice to the berries at the same time that you add the calcium water. You can make this recipe with cultivated blackberries. If they are quite sweet, however, you need to add 1/4 cup lemon juice when you add the calcium water to be sure they are acid enough for safe water bath canning.
Servings 5 cups


  • 3 quarts of blackberries *see note*
  • 2 Tablespoons lemon juice bottled, *see note*
  • 2 teaspoons calcium water see step #1
  • 1 ¼ cups sugar
  • 2 teaspoons Pomona’s Pectin powder 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 and rinse jars, lids, and screw bands. Set screw bands aside until ready to use. Place jars in boiling water bath canner with a rack, fill at least 2/3 of the way full with water, and bring to a boil. Boil jars for 10 minutes to sterilize (add 1 additional minute of sterilizing time for every 1000 feet above sea level), then turn down heat and let jars stand in hot water until ready to use. Place lids in water in a small pan, bring to a low simmer, and hold there until ready to use.
  • Pick through blackberries, discarding any stems. If blackberries look clean, rinsing them is optional.
  • Place berries in a large bowl and mash them thoroughly ( a potato masher works well for this).
  • Place a mesh strainer over a large bowl, and transfer mashed berries into the mesh strainer. Press the mashed berries through the strainer (the back of a wooden spoon, as well as clean fingers, work well for this), so that the blackberry pulp goes through the strainer into the bowl below, while the seeds remain in the strainer.
  • Measure out 4 cups of the blackberry pulp. (If you have any left over, you can use it for something else.) Pour the measured pulp into a large sauce pan. Add calcium water and stir to combine.
  • In a separate bowl, combine the sugar and pectin powder. Mix well and set aside.
  • Bring blackberry pulp to rolling boil over high heat. Add sugar-pectin mixture, then stir vigorously for 1 to 2 minutes, still over the highest heat, to dissolve pectin. Return jam to a boil, then remove from heat.
  • Remove hot jars from canner and fill jars with jam, leaving ¼ inch of headspace. Remove trapped air bubbles, wipe rims with a damp cloth, and put on lids and screw bands, tightening bands only to “fingertip tight” (until resistance is met, and then just the tiniest bit more).
  • Place jars in the hot water, on the rack inside the canner. (Make sure jars are upright, not touching each other or the sides of the canner, and are covered with at least 1-2 inches of water). Place the lid on the canner, return the canner to a rolling boil, and boil for 10 minutes. (Add 1 minute additional processing time for every 1,000 feet above sea level.)
  • Remove jars from canner.
  • Allow jars to cool undisturbed for 12-24 hours. Then, confirm that jars have sealed. Remove screw bands from sealed jars, rinse off outside of jars if necessary, label jars, and store for later use.


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11 Responses

  1. Elana
    | Reply

    Can I use agave powder instead of sugar?

    • Shelby Collings
      | Reply

      You sure can! Be sure to consult the packaging for conversions.

  2. Alecia
    | Reply

    Can I substitute honey granules for sugar and if so, is it 1:1?

    • Shelby Collings
      | Reply

      Hello Alecia,

      We have not worked with honey granules so we cannot say for sure. We would recommend starting with 1/2 of the called for amount of sugar and then adding more once the granules/pectin are dissolved, if you determine that you would like it to be sweeter.

  3. Leigh Cochrane
    | Reply

    How do I make blackberry jam without adding ant sweetener (no sugar, no artificial sweetener, no honey etc). My blackberries are tart and I like them that way.
    I want to use the canning method so that it last up to a year at least. I have already frozen the blackberries and I am not going to remove the seeds.
    Also so the fruit doesn’t turn brown or ugly looking..
    Thank you.

    • Shelby Collings
      | Reply

      Hello Leigh,

      *We don’t recommend making jam or jelly with absolutely no sweetener. The final product is likely to be tart and bland. Sweetener, even in a small amount, brings out the flavor of the fruit.

      If you want to try it, however, this is what you do: For 4 cups of mashed fruit or juice, use either ½ cup water or unsweetened fruit juice (if you’re using 2 or 3 teaspoons of pectin) or ¾ cup water or unsweetened fruit juice (if you’re using 4 teaspoons of pectin).

      Make liquid pectin by measuring the correct amount of water or juice into a small sauce pan and bringing it to a boil. Put boiling liquid in cup for immersion blender, or in food processor, or in blender. Add pectin. It is very important to vent the lid (if there is one) to let steam out. Don’t use an enclosed blender that can’t be vented. Blend for 10 seconds, then stop and scrape down the sides so all pectin clumps are in or on the liquid. Blend for a full minute until all powder is totally dissolved.

      Add the liquid pectin to the boiling fruit or juice mixture, which should already contain the calcium water and lemon juice (or lime juice or vinegar) if called for in the recipe. Stir while mixture returns to a full boil. If you taste your jam before jarring and it isn’t sweet enough, you can add however much sweetener you want at this point. Stir well and return mixture to a boil, remove from heat, jar and process according to the recipe sheet that comes with Pomona’s Pectin.

  4. Kristi
    | Reply

    How do i make TRUE freezer jam, without cooking and canning the berries? The flavor is so much more fresh without being cooked?

  5. Sue
    | Reply

    The recipe says, in 2 places, *See note below* but I cannot find any note on the page. What information is missing?

    • Shelby Collings
      | Reply

      Hello Sue,

      Great question! *see note* refers to the Note section of our recipes, just below the Print button and the recipe description.

  6. DoxieMom57
    | Reply

    Easy recipe.

    Doubled it and used a total of 2cups sugar and a food mill for seeding the berries.. Cleaned out the freezer of 2020’s wild crop of blackberries from the PNW.

    Perfectly tart and fruity

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