Blackberries make the most dramatic jam in the canning cupboard - nearly black in the jar, vivid purple the moment it hits toast, exactly as the photograph shows: an open jar beside a slice spread thickly, the set firm enough to hold its edges and glossy enough to catch the light. This recipe gets that set the old way, with a grated apple cooked in with the berries. Apple is rich in natural pectin, and it is the classic partner for blackberries - the jar in the photograph is a blackberry and apple jam, and the apple all but disappears into the finished flavour.
No boxed pectin means the set is a soft, spoonable jam set rather than a rubbery jelly one, and it depends on two things you control: a true rolling boil held for the full time, and a cold-plate test before the jars are filled, both covered in the steps. The lemon juice is doing double duty - brightening the berries and supporting the set. Newer canners often start with our easy blueberry jam; this one follows the same tested pattern on our Canning & Preserving shelf, with half-pints processed 10 minutes at altitudes up to 1,000 feet.
Seeds are the one honest decision in blackberry jam. This recipe keeps them - they are part of the fruit's character and most home jam-makers leave them. If your household disagrees, the notes explain the seedless route and what it costs you in yield.
The grated apple trick, and the set test
Blackberries alone are only moderate in pectin, and ripe ones run lower still. One tart apple, grated with its peel on and cooked down with the berries, supplies the missing pectin without a packaged product - choose a firm, sharp apple such as a Granny Smith. Judge the set by the cold-plate test rather than the clock: spoon a little jam onto a plate chilled in the freezer, wait 30 seconds, and push it with a finger. The surface should wrinkle and the jam should move reluctantly. If it runs, boil 3 minutes longer and test again on a clean cold spot.
Seedless, if you must
For a seedless jam, crush the berries, simmer them for 5 minutes in a splash of water until soft, then press them through a food mill or a sieve before measuring - you will need about 5 cups (750 g) of the resulting pulp and juice to replace the crushed fruit below, and the yield drops by roughly a jar. The apple goes in after milling, grated as written. Everything else, including the processing time, is unchanged.
Ingredients
- 6 cups fresh blackberries (900 g)
- 1 medium tart apple, grated with peel (180 g)
- 4 cups granulated sugar (800 g)
- 2 tablespoons bottled lemon juice (30 ml)
- 1/2 cup water (120 ml)
- 6 half-pint canning jars with two-piece lids (250 ml)
Amounts are for the yield below. US customary measures first, grams in brackets for scale users.
Step-by-step instructions
- Prep the canner and jars. Fill a water-bath canner and start it heating. Wash the jars and keep them hot; set the lids in warm water. Put two small plates in the freezer for the set test. Rinse the blackberries gently and pick out any soft or mouldy fruit.
- Crush and combine. Put the berries and water in a large, deep pot and crush them with a potato masher to a coarse, juicy pulp - leave plenty of pieces. Stir in the grated apple, lemon juice and sugar until the sugar is moistened throughout.
- Cook to the set point. Bring the mixture to a full rolling boil over medium-high heat, stirring often, then boil hard for 12 to 18 minutes, stirring more toward the end as it thickens and the bubbles turn slow and glossy. Test on a cold plate from minute 12: the jam should wrinkle when pushed. Boil longer and retest if it runs.
- Skim and rest. Take the pot off the heat and skim off any foam with a spoon. Let the jam stand for 2 minutes, stirring once - this brief rest keeps the fruit pieces suspended through the jars instead of floating to the tops.
- Fill the jars. Ladle the hot jam into hot half-pint jars, leaving 1/4 inch (0.6 cm) of headspace. Remove bubbles with a non-metal spatula, re-check the headspace, wipe the rims clean, and apply the lids and bands fingertip-tight.
- Process and cool. Lower the jars into the canner, cover them with at least 1 inch (2.5 cm) of water, and bring to a full rolling boil. Process half-pints for 10 minutes at altitudes up to 1,000 feet; add 5 minutes at 1,001 to 6,000 feet and 10 minutes above 6,000 feet. Rest the jars in the canner 5 minutes after the heat goes off, then cool undisturbed for 12 to 24 hours and check the seals.
Nutrition estimate
| Nutrient | Per serving |
|---|---|
| Calories | 55 kcal |
| Protein | 0 g |
| Carbohydrates | 14 g |
| Fat | 0 g |
| Saturated fat | 0 g |
| Sodium | 0 mg |
| Fiber | 1 g |
| Sugar | 13 g |
Nutrition figures are estimates calculated from standard ingredient data for the yield stated. Your actual values will vary with brands, substitutions and portion sizes — treat them as a guide, not a guarantee.
Storage & reheating
Store sealed jars in a cool, dark place and use within 12 months for the best colour and flavour. Once opened, refrigerate and use within 1 month. If a jar shows mould, fermentation bubbles or an off smell, discard it without tasting. Nutrition values are estimates per tablespoon and will vary with the sweetness of the berries.
Canning safety — read first
Home canning must follow tested processes exactly. The times on this page follow the structure of current USDA guidance for the stated jar size at 0-1,000 feet elevation; always confirm processing times and altitude adjustments in the USDA Complete Guide to Home Canning or the National Center for Home Food Preservation before you start. Never taste food from a jar with a failed seal, bulging lid or off odor — discard it.
Easy Blackberry Jam for Canning
Deep purple blackberry jam with a grated-apple pectin boost and a clean set.
Ingredients
Tick ingredients off as you prep, and tap a step below to mark it done as you cook. Scaling adjusts the listed amounts - seasoning to taste stays your call.
Instructions
- Prep the canner and jars. Fill a water-bath canner and start it heating. Wash the jars and keep them hot; set the lids in warm water. Put two small plates in the freezer for the set test. Rinse the blackberries gently and pick out any soft or mouldy fruit.
- Crush and combine. Put the berries and water in a large, deep pot and crush them with a potato masher to a coarse, juicy pulp - leave plenty of pieces. Stir in the grated apple, lemon juice and sugar until the sugar is moistened throughout.
- Cook to the set point. Bring the mixture to a full rolling boil over medium-high heat, stirring often, then boil hard for 12 to 18 minutes, stirring more toward the end as it thickens and the bubbles turn slow and glossy. Test on a cold plate from minute 12: the jam should wrinkle when pushed. Boil longer and retest if it runs.
- Skim and rest. Take the pot off the heat and skim off any foam with a spoon. Let the jam stand for 2 minutes, stirring once - this brief rest keeps the fruit pieces suspended through the jars instead of floating to the tops.
- Fill the jars. Ladle the hot jam into hot half-pint jars, leaving 1/4 inch (0.6 cm) of headspace. Remove bubbles with a non-metal spatula, re-check the headspace, wipe the rims clean, and apply the lids and bands fingertip-tight.
- Process and cool. Lower the jars into the canner, cover them with at least 1 inch (2.5 cm) of water, and bring to a full rolling boil. Process half-pints for 10 minutes at altitudes up to 1,000 feet; add 5 minutes at 1,001 to 6,000 feet and 10 minutes above 6,000 feet. Rest the jars in the canner 5 minutes after the heat goes off, then cool undisturbed for 12 to 24 hours and check the seals.
Recipe by Ahsan ul Haq · FryDaily. Printing? This card is designed to print cleanly on its own.
