Mary Berry Blueberry Jam Recipe

If you love the idea of a homemade jam that tastes like pure summer, this blueberry jam is a lovely one to keep in your back pocket. It sets into a soft, spreadable gel with a glossy finish, bursting with sweet blueberries and a gentle lift from lemon. It’s an easy, beginner-friendly preserve with no complicated equipment, just a little attention while it bubbles. Total time is about 45 minutes, plus cooling.

Ingredients

For the blueberry jam

750g blueberries (fresh, or frozen thawed and well-drained)
750g preserving sugar (or jam sugar)
2 tablespoons lemon juice

Optional (but helpful)

1 teaspoon unsalted butter (reduces foaming)
3 to 4 sterilised jam jars with lids (about 300 to 340g each)

How to Make Mary Berry Blueberry Jam Recipe

Prepare the oven: Preheat the oven to 140°C or 120°C fan. Wash jars and lids in hot soapy water, rinse well, then place the jars (not the rubber seals, if using) on a baking tray and heat for 15 minutes. Keep them warm so the jam doesn’t crack the glass.
Chill a plate for testing: Pop a small plate into the freezer. You’ll use this later to check the setting point quickly and reliably.
Mix the fruit and sugar: Tip the blueberries into a wide, heavy-based pan. Add the preserving sugar and lemon juice. Stir, then leave for 10 minutes so the sugar starts drawing out the juices.
Dissolve the sugar gently: Set the pan over low heat and stir regularly until the sugar has completely dissolved. Take your time here. If you boil before the sugar dissolves, the jam can turn grainy.
Cook to the setting point: Turn the heat up and bring the jam to a full rolling boil. Boil for 8 to 12 minutes, stirring occasionally and scraping the base of the pan to prevent sticking. If there’s a lot of foam, stir in the butter or skim with a spoon.
Test for set: Take the pan off the heat. Spoon a little jam onto the chilled plate, wait 1 minute, then push it with your fingertip. If it wrinkles and feels softly set, it’s ready. If it runs back quickly, boil for 2 more minutes and test again.
Cool briefly, then jar up: Let the jam sit for 5 minutes so the fruit settles evenly. Carefully ladle into warm sterilised jars, leaving a small gap at the top. Wipe rims clean and seal immediately.
Cool and label: Leave the jars undisturbed until fully cold. Label with the date. Once opened, store in the fridge.

Tips

How do I know when blueberry jam is set without a thermometer?

The chilled-plate wrinkle test is the most dependable. If the jam wrinkles when you push it and doesn’t flood back into the line, it’s at a good soft-set. If you prefer it firmer, give it another 1 to 2 minutes at a rolling boil, then test again.

Why is my jam runny?

It usually just needs a little longer at a proper rolling boil. Blueberries vary in natural pectin, so timings are never identical. Reheat the jam, boil for 2 to 4 minutes, then re-test on a chilled plate.

How do I stop my jam from burning on the bottom?

Use a wide, heavy-based pan and keep the heat low while dissolving the sugar. Once boiling, stir occasionally and scrape along the base of the pan, especially around the edges where it can catch.

Can I make this jam less sweet?

Traditional jam needs sugar for set and shelf life. If you reduce the sugar, it will be looser and won’t keep as long. For a lower-sugar version, use a sugar-reduced pectin and follow the packet instructions rather than swapping sugar in a classic recipe.

Serving Suggestions

Spread thickly on warm toast with salted butter
Spoon into porridge or overnight oats
Serve with scones, clotted cream, and fresh berries
Use as a filling for Victoria sponge, jam tarts, or thumbprint biscuits
Swirl into Greek yogurt with a handful of granola

Storage

Room temperature

Store sealed, cooled jars in a dark, cool cupboard for up to 12 months. Keep the jars away from heat and direct sunlight to protect the colour and flavour.

Refrigerator

Once opened, refrigerate and use within 4 to 6 weeks. Always use a clean spoon to prevent mould.

Freezing

Jam freezes well for up to 3 months. Freeze in freezer-safe containers with a little headspace for expansion. Thaw overnight in the fridge and stir well before using.

Nutrition

Calories: 52 kcal
Carbohydrates: 13 g
Protein: 0 g
Fat: 0 g
Saturated Fat: 0 g
Sodium: 1 mg

Disclaimer: Nutrition values are estimates and will vary depending on ingredient brands and portion size.

FAQs

Can I use frozen blueberries for blueberry jam?

Yes. Thaw them first and drain off excess liquid, then cook exactly the same way. Frozen berries can release more water, so you may need an extra 2–5 minutes of boiling to reach the setting point.

Do I need pectin to make blueberry jam?

Not always. Preserving sugar (or jam sugar) contains added pectin, which makes setting easier and more consistent. If you use standard granulated sugar, the jam can still work, but it may take longer to set and the yield can be slightly looser.

Why has my jam crystallised or turned grainy?

This usually happens when the sugar wasn’t fully dissolved before the jam boiled, or if it was stirred too vigorously while boiling. Next time, keep the heat low until the sugar has completely dissolved, then boil hard and stir only occasionally.

How can I fix jam that didn’t set?

Pour the jam back into the pan, bring it to a rolling boil for 2–4 minutes, then test again with the chilled plate. If it still won’t set, add a little extra lemon juice or use a jam-setting (pectin) powder and follow the packet guidance.

How long should I boil blueberry jam?

Once the sugar has dissolved, it typically takes 8–12 minutes at a rolling boil to reach a soft setting point, but it can vary. Use the chilled-plate test rather than relying on the clock alone.