How do I make blackberry jam?

Blackberry jam from a tested recipe is 6 cups crushed, fully ripe blackberries, one package of powdered pectin and 8 1/2 cups of sugar, boiled hard for 1 minute and processed in sterilized jars, for 11 or 12 half-pints. That is the National Center for Home Food Preservation (NCHFP) recipe. Blackberries vary more than most fruit: slightly underripe berries carry enough pectin and acid to set with sugar alone, while fully ripe ones may not. This page shows how ripeness changes your recipe choice, compares jam with jelly from the same bucket, covers seeds and wild berries, and gives processing by elevation.

Ripeness decides the route

NCHFP sorts fruit by how much pectin and acid it brings to the pot. It lists sour blackberries in its "sets on its own" band, fruit with enough of both to gel with sugar alone, and ripe blackberries in its "may need help" band, fruit that may need pectin or acid added [1]. The same berry can fall on either side depending on when you picked it.

Here is how that plays out:

Washington State University Extension advises that blackberries for jam should be "not too ripe" [6]. Pomona's directions for its calcium-set pectin require 1 tablespoon of lemon juice per cup for sweet blackberries and make it optional for sour ones [7]; that rule belongs to Pomona's pectin and does not carry over to NCHFP's recipes, which add no lemon.

The NCHFP blackberry jam with powdered pectin

The recipe in order [4]:

1. Sterilize canning jars and prepare two-piece canning lids according to the manufacturer's directions.
2. Sort and wash fully ripe berries and remove any stems or caps. Crush them. If they are very seedy, put part or all of them through a sieve or food mill.
3. Measure 6 cups of crushed berries into a kettle, add one package of powdered pectin, and stir well.
4. Over high heat, stirring constantly, bring quickly to a full boil with bubbles over the whole surface.
5. Add the 8 1/2 cups of sugar, continue stirring, and heat again to a full bubbling boil.
6. Boil hard for 1 minute, stirring constantly.
7. Remove from heat and skim.
8. Fill hot jam immediately into hot, sterile jars, leaving 1/4 inch headspace. Wipe the rims with a dampened clean paper towel and adjust two-piece metal canning lids.
9. Process in a boiling water canner (chart below).

Seed removal in this recipe is optional and done before measuring [4]. If you sieve, you will need more than 6 cups of crushed berries to end up with 6 cups of pulp.

Jam or jelly from the same berries

Blackberry jelly is just as well documented as the jam, and NCHFP has three versions. Jelly takes more fruit for fewer jars because you keep only the juice.

For the no-pectin jelly, NCHFP's method calls for about 3/4 ripe and 1/4 underripe fruit, no more than 6 to 8 cups of juice at a time, and at least 1 cup of clear juice from each pound of fruit [3]. The liquid pectin jelly is the forgiving choice when your berries are all ripe. Extracting clear juice is its own skill, covered on extracting juice for jelly, and the full jelly method is on how to make jelly.

Wild and roadside blackberries

WSU describes three common wild blackberries in the Northwest: the Himalayan, sweet when eaten fresh, though some find it too seedy for cooking; the evergreen, a favorite for pies, jellies and jams; and the native trailing blackberry, which WSU calls outstanding and highly prized [6]. If your Himalayan berries seem seedy, that is a good reason to sieve some or all of the crushed fruit.

Two practical cautions for wild fruit:

• Know where it grew. Roadside and ditch-bank plants may have been sprayed. WSU warns against using rose hips from sprayed roses [6], and the same reasoning applies to any wild fruit you cannot vouch for.
• Check before you sell. Food rules commonly require ingredients from an approved source. One California county's cottage food rules state that no fruit picked or grown in the wild is allowed [8]. Ask your regulating agency before you sell wild blackberry jam, and see preserves cottage food laws often exclude.

For selling under the standard name, blackberry is a federal Group I fruit, so the jam needs at least 47 parts fruit to 55 parts sugar [9]. Dewberry is listed separately in the same group [9].

Processing blackberry jam and jelly

NCHFP's blackberry jam and jelly recipes with pectin give this chart, in sterilized jars [4] [5], and NCHFP's no-pectin jams and jellies use the same 5, 10 and 15 minute steps [11]:

NCHFP says jars must be pre-sterilized for any process shorter than 10 minutes [10]. If you skip sterilizing, follow the unsterilized-jar chart on how long to process jam, which starts at 10 minutes and steps up with altitude.

Blackberries in the off season

If you picked more than you can cook this week, freeze them. WSU's method is to wash a small amount at a time in cold water, drain, freeze on a cookie sheet, then pack in moisture- and vapor-proof containers [6]. Remember that frozen berries behave like fully ripe fruit, so plan on a pectin recipe. How to buy, pick and freeze fruit for jam is on choosing and buying fruit for jam, and the sister berry is on raspberry jam.

References

1. National Center for Home Food Preservation, Jellied Product Ingredients, accessed October 2026. https://nchfp.uga.edu/how/make-jam-jelly/jams-jellies-general-information/jellied-product-ingredients/
2. NC State Extension (copy of NCHFP recipes), Preserving Blueberries: Recipes from NCHFP (Berry Jam without added pectin), 2015. https://foodsafety.ces.ncsu.edu/wp-content/uploads/2015/09/Preserving-Blueberries-Recipes-from-NCFHP.pdf
3. National Center for Home Food Preservation, Making Jelly without Added Pectin (Table 2), accessed October 2026. https://nchfp.uga.edu/how/make-jam-jelly/jams-jellies-general-information/making-jelly-without-added-pectin/
4. National Center for Home Food Preservation, Blackberry Jam with Powdered Pectin, June 2005, adapted from USDA Home and Garden Bulletin No. 56 (1982). https://nchfp.uga.edu/how/make-jam-jelly/jams/blackberry-jam-pectin/
5. National Center for Home Food Preservation, Blackberry Jelly with Liquid Pectin, June 2005. https://nchfp.uga.edu/how/make-jam-jelly/jellies/blackberry-jelly-liquid-pectin/
6. Washington State University Extension, Lewis County, Preserving Washington's Wild Berries, undated. https://wpcdn.web.wsu.edu/wp-extension/uploads/sites/2057/2021/04/Preserving-Washingtons-Wild-Berries-1.pdf
7. Pomona's Universal Pectin, Create Your Own Recipe: Developing or Converting Recipes for Cooked Jam or Jelly Using Pomona's Pectin, modified August 24, 2023. https://pomonapectin.com/?p=21164
8. Plumas County (California) Environmental Health, Cottage Food Operations: Requirements for Fruit Butters, Jams, Jellies and Preserves, rev. January 25, 2016. https://ca-plumascounty.civicplus.com/DocumentCenter/View/44685/CFO-Jams-and-jellies-Part-150-Self-certification-11-7-13
9. U.S. Code of Federal Regulations, 21 CFR 150.160, Canned fruit preserves and jams (Cornell LII text, current). https://www.law.cornell.edu/cfr/text/21/150.160
10. National Center for Home Food Preservation, Do I Need to Pre-Sterilize My Jars before Canning?, May 21, 2014. https://nchfp.uga.edu/blog/do-i-need-to-pre-sterilize-my-jars-before-canning
11. USDA, Complete Guide to Home Canning, Guide 7: Preparing and Canning Jams and Jellies, rev. 2015. https://nchfp.uga.edu/papers/guide/GUIDE07_HomeCan_rev0715.pdf