This blackberry season try my slow cooker blackberry jam – hands-off jam that tastes great!
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I was inspired to make this recipe after picking loads of delicious blackberries from the local pick your own farm.
Jam is a great way to preserve and enjoy late summer fruit later in the year.
Using the slow cooker method makes jam-making so simple, you don’t need to stand over a pot on the stove stirring and checking the temperature for ages.
Just throw in the ingredients, leave for a while then you’re ready to jar up!
This is great for busy people or if you don’t have the traditional jam-making equipment.
The recipe makes a couple of jars so the small batch is useful too.
Ingredients
Here is what you will need to make this easy slow cooker blackberry jam recipe.
Get the quantites from the detailed recipe card at the bottom of the post.
- blackberries – blackberries you have picked by hand (either on a country walk or from a fruit farm) work really well, but so do blackberries from the supermarket.
- jam sugar – if you don’t have jam sugar (which is normal sugar with pectin pre-added) then you can use normal granulated sugar (regular sugar) and add a sachet of pectin.
When making slow cooker jam, especially using a low-pectin fruit like blackberries, it is best to include pectin for best results. - lemon juice – either from a fresh lemon or from a bottle of lemon juice. Including lemon juice in the recipe is another way to increase the pectin in this slow cooker jam.
Method
Before you start, read my step-by-step instructions, with photos, hints and tips so you can make this blackberry jam recipe perfectly every time.
Scroll down for the recipe card with quantities and more tips at the bottom of the page.
- Wash the blackberries and remove any stalks or leaves.
- Put the blackberries, jam sugar and lemon juice in the slow cooker. Cook on low for 1 hour. After 1 hour, stir to mix the fruit and sugar together, replace the lid and cook for a further 1 hour on low. Here your aim is to ensure the sugar dissolves fully.
- After the two hours, mash the fruit gently using the back of a fork then switch to high. Cook for 2-3 hours.
- You’ll find the jam thickens as it cooks.
- You should find it is possible for the jam to reach the jam setting temperature of 105°C (220°F) even in the slow cooker! I check this after 2 hours of cooking (i.e. 4 hours from the start).
To check if the jam has reached setting point, you can either use a food thermometer as I have done here or you can use the wrinkle test.
For the wrinkle test you will drop a small spoon of the hot jam onto a chilled saucer or small plate (put one into the freezer at the start). Let it cool for a minute, then push with your finger. If it wrinkles on the plate it has reached setting point. If not, leave it on high for another hour.
- When you are sure it has reached setting point (by checking temperature or doing the wrinkle test), pour the jam into sterilised jam jars and seal.
Recipe tips
- To increase the pectin levels in your jam, include some underripe blackberries if you can. They naturally have more pectin than ripe blackberries! Blackberries are a fruit which is naturally quite low in pectin. This will be easier to achieve if you pick the blackberries yourself of course, as you won’t find underripe fruit in stores.
- Slow cooker jam doesn’t come to a rolling boil like jam made the traditional way in a jam pan.
Due to this, slow cooker jam doesn’t reduce in the same way which means it naturally contains more water than traditional jam.
This is why we use jam sugar which contains pectin (instead of just normal sugar) in this recipe to help compensate for that higher proportion of water. The pectin helps to achieve that thicker jam consistency. You will most likely still notice that this jam has a slightly looser set than standard jam. - Caramelisation – when jam is cooked for a long period of time, such as in a slow cooker, you might find that the sugars in the jam start to caramelise. This can usually be seen from the colour of the jam changing, and becoming more of a brown colour. To avoid this, stop cooking as soon as your jam has reached the setting point and don’t leave it to cook too long.
Sterilising jars
I love a shortcut so I use my dishwasher or oven for help with sterilising jars when I make jam.
Putting the jars and metal lids in a hot wash in your dishwasher will sterilise them fully.
Otherwise you can wash them by hand in hot soapy water, leave wet and pop them in the oven (upside down on a clean baking tray) set to 120°C (250°F) for 10-20 minutes until dry.
Variations
Why not try this recipe with different fruit/berries like raspberries, strawberries or cherries to change it up.
My slow cooker blueberry jam is a favourite here too.
Serving
There are so many ways you can use blackberry jam, but spread on bread or toast or between the layers of a cake are my favourites.
It works really well with all kinds of baked goods. Why not fill a blackberry scone with blackberry jam, delicious!
Recipe
Slow Cooker Blackberry Jam
You’ll only need three recipes to make this tasty jam and your slow cooker does most of the work. Perfect to use your foraged blackberries this autumn.
Servings: 30
Calories: 67kcal
Ingredients
- 650 g blackberries
- 450 g jam sugar
- 3 tbsp lemon juice (from 1 and a half lemons)
Instructions
-
Wash the blackberries and remove any stalks or leaves.
650 g blackberries
-
Put the blackberries, jam sugar and lemon juice in the slow cooker. Cook on low for 1 hour. After 1 hour, stir to mix the fruit and sugar together, replace the lid and cook for a further 1 hour on low. Here your aim is to ensure the sugar dissolves fully.
450 g jam sugar, 3 tbsp lemon juice
-
After the two hours, mash the fruit gently using the back of a fork then switch to high. Cook for 2-3 hours.
-
You’ll find the jam thickens as it cooks.
-
You should find it is possible for the jam to reach the jam setting temperature of 105°C (220°F) even in the slow cooker! I check this after 2 hours of cooking (i.e. after 4 total hours).
-
To check if the jam has reached setting point, you can either use a food thermometer as I have done here or you can use the wrinkle test.For the wrinkle test you will drop a small spoon of the hot jam onto a chilled saucer or small plate (put one into the freezer at the start). Let it cool for a minute, then push with your finger. If it wrinkles on the plate it has reached setting point. If not, leave it on high for another hour.
-
When you are sure it has reached setting point, pour the jam into sterilised jam jars and seal.
Notes
- To increase the pectin levels in your jam, include some underripe blackberries if you can. They naturally have more pectin than ripe blackberries! Blackberries are a fruit which is naturally quite low in pectin. This will be easier to achieve if you pick the blackberries yourself of course, as you won’t find underripe fruit in stores.
- Slow cooker jam doesn’t come to a rolling boil like jam made the traditional way in a jam pan.
Due to this, slow cooker jam doesn’t reduce in the same way which means it naturally contains more water than traditional jam.
This is why we use jam sugar which contains pectin (instead of just normal sugar) in this recipe to help compensate for that higher proportion of water. The pectin helps to achieve that thicker jam consistency. You will most likely still notice that this jam has a slightly looser set than standard jam. - Caramelisation – when jam is cooked for a long period of time, such as in a slow cooker, you might find that the sugars in the jam start to caramelise. This can usually be seen from the colour of the jam changing, and becoming more of a brown colour. To avoid this, stop cooking as soon as your jam has reached the setting point and don’t leave it to cook too long.
Sterilising jars
Putting the jars and metal lids in a hot wash in your dishwasher will sterilise them fully.
Otherwise you can wash them by hand in hot soapy water, leave wet and pop them in the oven (upside down on a clean baking tray) set to 120°C (250°F) for 10-20 minutes until dry.
