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Blackberry jam is a classic homemade preserve made with just berries, sugar, and a bit of time at the stove. You don’t need fancy ingredients or store-bought pectin, just fresh berries, a bit of sugar, and some patience at the stove.
Blackberry jam is my husbands very favorite preserves, and it’s the one jam that we make every single summer without fail. With just a few ingredients and a little time at the stove, you can turn fresh summer berries into a thick, flavorful spread that’s good on just about everything.
Blackberries are naturally high in both acid and pectin, which means they gel easily without added thickeners. That makes this one of the best jams for beginners, and one of the easiest to adapt based on your personal taste. Even if you’ve never made jam before, this is a great place to start.
This particular jam works well as a low sugar jam and as a standard preserve, and I’ve included instructions for both variations. You can choose to use more or less, or anywhere in between.
Choosing Blackberries for Jam
Any kind of blackberry works here—wild, cultivated, or even frozen berries.
Wild blackberries tend to have more pectin and firmer fruit. The berries will likely stay whole in the jam, unless you choose to mash them. If you’re foraging wild blackberries like we often do, be sure to pick them fully ripe. Slightly underripe berries can be pretty tart, which is fine in a jam, but they don’t release juice as easily during cooking.
Cultivated blackberries tend to be a bit juicier and sweeter, and will fall apart into a smoother jam. If you’re using sweeter cultivated berries, you may want to add a splash of lemon juice for balance.
Frozen blackberries have a bit less pectin, as freezing breaks down pectin in fruit. Be aware that while it’ll still set with frozen fruit, it may have a less firm set and slightly lower yield than with fresh fruit.
Whatever fruit you choose, this recipe for blackberry jam will help you create a delicious preserve that showcases the luscious flavor of fresh summertime blackberries.
Sugar Options for Blackberry Jam
This recipe works with just about any amount of sugar. Here are a few ratio guidelines to help you choose the right version for your taste:
- Perfect Blackberry Jam: Use 4 cups sugar to 6 cups mashed fruit. This is the amount currently recommended by the National Center for Food Preservation.
- Low Sugar: Use 2 cups to 6 cups mashed fruit. A nice set, but reasonably tart and more fruit forward. The perfect spot for if you like low sugar but still want a high quality jam.
- Old Fashioned High Sugar (Traditional): Equal parts sugar and mashed fruit. Very sweet with a firm set and high yield. This one is too sugary for me, but some people really love those old fashioned candy preserves. This level of sugar was used to preserve the jam hundreds of years ago before canning, but it’s less dependable for preservation than a simple waterbath, and it’s crazy sweet.
You can also use honey or maple syrup instead of sugar—just keep in mind that they’re sweeter by volume. Start with about two-thirds the amount of sugar and taste as you go. (A thermometer helps here, since the visual cues are harder to read with alternative sweeteners.)
No matter how much (or little) sugar you use, the jam will still be safe for water bath canning because blackberries are naturally high in acid.
Making Blackberry Jam Without Pectin
Start by combining your mashed berries and sugar in a jam pot. If you’re using lemon juice, add it now. I like about a tablespoon per quart of berries when I’m working with sweet cultivated blackberries, but skip it if your berries are already on the tart side.
Fresh lemon juice has better flavor than bottled, and since blackberries are already acidic enough for canning, you don’t have to use bottled for safety. Go with fresh if you can get it.
Bring the mixture to a boil over medium-high heat. Blackberry jam tends to foam a lot—keep a close eye and stir frequently. Make sure you’re using a deep pot!
Some people add a little butter (about 1/4 tsp) to reduce foaming, and that’s considered safe even for canning, but I usually don’t. I just stay present and stir, which keeps the foam down naturally.
Stirring continuously helps keep your jam from overflowing, and makes sure you’re right there so you don’t miss set point. Beyond that, the National Center for Food Preservation notes that, “Adding 1/2 teaspoon of butter or margarine with the juice and pectin will reduce foaming. However, these may cause off-flavor in long-term storage of jellies and jams.”
So I skip the butter, unless the foaming is really getting out of hand and I worry the jam will overflow the pot (even with stirring it down).
As the jam cooks, the foam will subside, and the mixture will thicken and turn glossy. This is your cue that you’re getting close to gel stage.
Testing for Gel Stage
I keep a spoon and a small plate in the freezer. When the jam looks thick, I spoon a little onto the cold plate, wait 30 seconds, and run a spoon through it. If it wrinkles slightly and holds a line, it’s ready. If not, give it a few more minutes.
You can also use an instant-read thermometer to check for gel stage. For most jams, that’s around 220°F at sea level. If you’re at higher elevations, subtract 2°F for every 1,000 feet above sea level. Once the jam hits the setting temperature for your elevation, it’s ready to jar.
Canning Instructions
Ladle the hot jam into prepared jars, leaving 1/4-inch headspace. Wipe the rims, apply 2-piece lids, and process in a boiling water bath:
- 10 minutes below 6,000 feet
- 15 minutes above 6,000 feet
Let the jars cool completely and check seals before storing. Properly canned blackberry jam will keep in the pantry for 12–18 months.
Troubleshooting
This recipe is pretty foolproof, but still, there are a few things that can go wrong along the way:
The most common reason is undercooking. Without added pectin, this recipe relies on evaporation and temperature to set. Keep cooking until the jam reaches gel stage (220°F at sea level, or 8°F above your local boiling point). You can test for doneness on a cold plate or with an instant-read thermometer.
This could be due to low heat. The jam needs to be cooked on high or medium high to activate the pectin, and it may not set if gently simmered. Try turning the burner up to medium-high as it thickens, and stir constantly to avoid scorching. Often it may not look like it’s thickening when it’s still hot, but it’ll still set when it cools. Check the temperature with an instant read thermometer to monitor progress as it cooks and be sure to cook it all the way until it reaches its set point.
If it’s too thick, stir in a bit of boiling water before using it, or warm the jar to loosen it. It still makes a great glaze for cakes, roasted meats, or drizzled over ice cream. Next time, be sure to check progress with a thermometer and remove it from the heat as soon as it reaches set point so you don’t overcook it.
Blackberry Jam Variations
For a naturally sweetened version, you can substitute all or part of the sugar with honey or maple syrup, using about 2/3 as much as you would with sugar. Just know that lower sugar versions may take a bit longer to reach gel stage.
If you prefer a seedless spread, you can run the berries through a fine mesh strainer or food mill to remove the seeds before making the jam. That way, you still get the pulp to help set the jam, but no seeds.
Or, you can make Blackberry Jelly by cooking the berries with a splash of water and straining through a jelly bag. With jellies, all the pulp is strained out. Measure the juice and proceed with the instructions in my blackberry jelly recipe.
Want to add a flavor twist? Stir in a splash of Chambord or cassis liqueur after cooking, just before jarring. A pinch of cinnamon or cardamom gives a warm, spiced flavor, or mix in raspberries, blueberries, or cherries for a custom blend.
Blackberry Jam Recipe Without Pectin
Ingredients
- 6 cups mashed blackberries, see note
- 4 cups granulated sugar
- 2 tablespoons lemon juice, optional, see notes
Instructions
- Prepare the canning setup: Wash and sterilize 6 to 7 half-pint jars. Place new lids in hot water (not boiling) and prepare your boiling water bath canner. Keep everything hot until ready to fill.
- Crush the berries: Rinse and sort your fresh blackberries, removing any stems or debris. Use a potato masher to crush them in a large mixing bowl or directly in the jam pot. It generally takes 2 cups whole fruit to make 1 cup mashed.
- Combine fruit and sugar: Place the crushed blackberries in a large, deep jam pot. Stir in the sugar and optional lemon juice (if using, see notes). Mix thoroughly to help the sugar dissolve slightly before heating.
- Bring to a boil: Turn the heat to medium-high and bring the mixture to a steady boil, stirring frequently to prevent scorching. Blackberry jam tends to foam quite a bit, so stay nearby and stir often.
- Cook to gel stage: Continue boiling the jam, stirring constantly, until it thickens and reaches gel stage. This typically takes 20 to 30 minutes, but times vary. Test for doneness using one or more of the following methods (see notes).
- Remove from heat and skim foam: Once gel stage is reached, remove the pot from heat and skim off any remaining foam if desired.
- Ladle into jars: Carefully ladle the hot jam into prepared jars, leaving ¼ inch headspace. Wipe the rims with a clean damp cloth, apply lids and screw on bands until fingertip tight.
- Process in a water bath canner: Place the jars in the boiling water bath canner, ensuring they’re fully submerged with at least 1–2 inches of water above the lids.Process both pint and half pint jars for 10 minutes, or 15 minutes if above 6,000 feet in elevation.
- Cool and store: After processing, remove jars and let them sit undisturbed for 12–24 hours. Check seals, label, and store in a cool, dark place for up to 18 months.
Notes
- Plate Test: Place a spoon and plate in the freezer. When you think the jam is ready, spoon a small amount onto the plate. After 30 seconds, run your finger through it. If it wrinkles and holds a line, it’s done.
- Thermometer Test: Jam sets at 220°F at sea level. Subtract 2°F for every 1,000 feet of elevation. Use an instant-read thermometer to check.
- Sheeting Test: Dip a spoon into the jam, hold it sideways over the pot, and watch how the jam falls. If it falls off in a sheet or a slow blob (not individual droplets), it’s likely ready.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
Blackberry Jam FAQ
Yes! Blackberries are naturally high in pectin, so they don’t need any added commercial pectin to gel. With a bit of patience and the right sugar-to-fruit ratio, you can get a perfect set using just blackberries, sugar, and optionally lemon juice.
If your jam isn’t setting, it likely just needs more time on the stove. Continue simmering and stirring until it thickens and begins to look glossy. Keep the heat on low toward the end to prevent scorching, and test for set with a cold plate from the freezer.
Absolutely. You can make a no-sugar-added blackberry jam that’s still safe for canning, as long as you follow proper processing times. The texture may be looser as there’s no sugar to set the pectin, and, of course it’ll be very tart, but the flavor will be bright and intensely fruity.
Blackberry jam tends to foam heavily as it cooks, especially in the early stages. Stirring frequently and maintaining a steady boil will help manage the foam. Some people add a small amount of butter (1/4 to 1/2 tsp) to reduce foaming, though this is optional.
Lemon juice isn’t necessary for safe canning with blackberries, but it helps brighten the flavor and balance sweetness—especially in low sugar versions. It also adds a bit of extra pectin, which can be help the jam set.
Process both half-pint and pint jars in a boiling water bath canner for 10 minutes at elevations up to 6,000 feet. If you’re above 6,000 feet, increase the processing time to 15 minutes.
It’s important to stick to small batches with no added pectin jams, as they don’t cook evenly in big batches, which can impact set. This recipe can be doubled easily without issue, but I wouldn’t recommend increasing it beyond that.
Preserving Blackberries
Looking for more ways to preserve blackberries?
Hi! Thank you so much for the recipe. What are the preservation times of this low sugar jam? If I seal it, Would it last 5 months? Thank you
If sealed in a waterbath canner, low sugar jams last just as long as full sugar jams. The canning is what’s doing the preservation, not the sugar. That’s so long as they’re sealed. Once opened, however, low sugar jams spoil in the fridge much faster than full sugar. Expect to eat a low sugar jam in 2-3 weeks, where as higher sugar jams can last months in the refrigerator.
Oh, my! What an excellent and easy recipe! My most favorite jam in the whole world is boysenberry, and I picked some fresh ones up at a local farmers market and used this recipe. Used 6 cups berries, 2/3 cups maple syrup, 2 tablespoons of granulated sugar, 2 tablespoons of lemon juice, half a teaspoon of refined (so no flavor) coconut oil, and at the very end before filling the jars, I added half a tablespoon of Chambord (black raspberry liquor). Totally mind blowingly delicious. I don’t mind the seeds, but some of my gift recipients do, so I’ll consider sieving them out the next time I make this jam. Thank you, Ashley!
You’re quite welcome!
Absolutely delicious and great consistency. LOVE IT.
So glad you liked it!
How long does this recipe roughly keep, unopened or opened, in the fridge?
It should keep several weeks in the fridge once opened, assuming you keep it free of contamination. What really gets jam is when you use a dirty spoon (with crumbs or butter, etc) to serve it. If you use a clean spoon to serve it lasts a lot longer. Unopened, they should last a really long time in the fridge. The only thing to watch out for is visible mold on the top, and that’s when you know to throw it out. Absent that, it’s probably still good. Enjoy!
This sounds deceptively easy, can’t wait to try. But is there a way to get the seeds out?
If you want to get the seeds out, briefly cook the blackberries while mashing them, and then pass it through a fine mesh strainer or food mill to remove the seeds. Or, alternately, you can make blackberry jelly instead which is seedless: https://practicalselfreliance.com/blackberry-jelly/
This receipe was wonderfully simple and absolutely delicious! My mom loves blackberry jam. She grew up in the south and grew up eating this. We used less sugar and it was still devine.Thank you!
So glad you enjoyed it!
Thank you for such a simple but delicious recipe. I appreciate your explanation about the amount of sugar or no sugar suggestions. I am very pleased with the results. Yummy!!!!
I’ve made the equal parts sugar/ blackberries and your low sugar recipe and yours is by far the best recipe ive come across. This is the first review I’ve ever left for any recipe that I’ve ever cooked! It’s that good ! 😎
That’s wonderful. We’re so glad you liked it.
Hi Ashley I made this blackberry jam last night using 10 c. blackberries, 6 c. sugar and 5-6 Tbsp. lemon juice.
It turned out good and had a semi-firm set. I cooked it for about 45-60 minutes (I wasn’t really paying attention to the time). We tried some today on bread and peanut butter and it’s delicious! Thank you for sharing a recipe that doesn’t require pectin. I have been really missing the availability of Certo Light (pectin for low sugar jams). Jean
You’re very welcome. We’re so glad you enjoyed the recipe.
Jam turned out fantastic with just one cup of sugar.
Is it possible to add jalapenos safely to the jam recipe?
It’s not a good idea to just add jalapenos to the blackberry jam since the jalapenos are a non-acidic food and can affect the acidity of the recipe. You might be able to find a recipe that has been tested for safety.
Sorry for my stupid question, but what would be the weight ( ounces or grams) of your 5 cups of blackberries.
Thanks so much 🙂
It’s not a stupid question at all but I’m not sure exactly what the weight would be. I did do a quick internet search and it looks like 1 cup of blackberries weighs roughly 5 ounces. So you could start out around 25 ounces and see how that works.
I would like to make a blackberry Pear Jam but I am definitely a beginner and not sure on my ratios, plus with adding the pear, Do I have to use pectin or does it still gel because of the blackberries?
Pears are also a high pectin fruit. We actually have a recipe for pear jam with no pectin as well. You should definitely be able to incorporate the pears into this recipe with no problem.
If you make this recipe the way it was written by Ashley you cannot go wrong. And the taste with less sugar is absolutely fabulous! I love that you don’t even need pectin with the rising costs of it. Thank you Ashley!