Step 1

Before you begin, prepare calcium water.To do this, combine ½ teaspoon calcium powder (in the small packet in your box of Pomona’s pectin) with ½ cup water in a small, clear jar with a lid. Shake well.Extra calcium water should be stored in the refrigerator for future use.

Step 2

Wash and rinse jars, lids, and screw bands. Set screw bands aside until ready to use. Place jars in boiling water bath canner with a rack, fill at least 2/3 of the way full with water, and bring to a boil. Boil jars for 10 minutes to sterilize (add 1 additional minute of sterilizing time for every 1000 feet above sea level), then turn down the heat and let jars stand in hot water until ready to use. Place lids in water in a small pan, bring to a low simmer, and hold there until ready to use.

Step 3

Rinse the blackberries, then place them in a mixing bowl and mash them. (A potato masher works well for this.).

Step 4

Measure out 4 cups of the mashed berries. (If you have any left over, you can use it for something else). Pour the measured mashed berries into a large saucepan. Add finely chopped rosemary, lemon juice, and calcium water, then stir to combine.

Step 5

In a separate bowl, combine the sugar and pectin powder. Mix well and set aside.

Step 6

Bring the berry mixture up to a rolling boil over high heat. Add the sugar-pectin mixture, then stir vigorously for 1 to 2 minutes, still over the highest heat, to dissolve pectin. Return jelly to a boil, then remove from heat.

Step 7

Remove hot jars from canner and fill jars with jam, leaving ¼ inch of headspace. Remove trapped air bubbles, wipe rims with a damp cloth, and put on the lids and screw bands, tightening bands only to “fingertip tight” (until resistance is met, and then just the tiniest bit more).

Step 8

Place jars in the hot water, on the rack inside the canner. (Make sure jars are upright, not touching each other or the sides of the canner, and are covered with at least 1-2 inches of water). Place the lid on the canner, return the canner to a rolling boil, and boil for 10 minutes. (Add 1 minute additional processing time for every 1000 feet above sea level.)

Step 9

Turn off heat and allow canner and jars to sit for 5 minutes. Then, remove jars from canner.

Step 10

Allow jars to cool undisturbed for 12-24 hours. Then, confirm that jars have sealed. Remove screw bands from sealed jars, rinse off outside of jars if necessary, label jars, and store for later use.