Blackberry bushes are tenacious plants that produce sweet little fruits in summer. If you have some of these bushes in your yard, you'll likely wind up with tons of delicious wild blackberries. Gather up the ripe berries to make some jam, which you can keep in the pantry for up to a year.
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Picking and Preparing Wild Blackberries
When the wild blackberries are evenly black, they're ripe and ready to pick. Take care to avoid the sharp thorny prickles on some blackberry plant varieties and wear gloves to help protect your hands from scratches. Remove the stems and leaves. Check the berries for insects and their larvae. If you notice any larvae, soak the blackberries in a salt solution made with 1/4 cup of salt per quart of water for 15 minutes to draw the larvae out, recommends the Rutgers New Jersey Agricultural Experiment Station. Discard any bruised, moldy or soft berries. Rinse the berries under running water and drain them in a colander.
Mashing and Deseeding the Blackberries
Add the blackberries in layers to a pot. Crush each layer with a potato masher. Blackberries have seeds and wild types may have more seeds than those from the store. If you don't like the crunchy seeds, you can remove them from the mashed berries using a food mill or metal mesh sieve. Boiling the mashed berries with water or apple juice, about 1/4 cup per pound of berries, for a minute in a large pot can further soften them to make removing the seeds easier.
Making the Jam
Combine the mashed, deseeded blackberries with an equal quantity of sugar. Don't skimp on sugar because it's what makes the jam gel properly. Add pectin according to the package directions. Blackberries don't have much natural pectin, and this helps the jam thicken without having to cook it for a long time and constantly check it to see if it will gel when cooled. While you can add lemon or lime juice to add tart flavor to the jam, it isn't necessary for proper gelling. Bring the jam mixture to a rolling boil over medium-high heat, stirring it regularly. Boil the jam for one minute. Skim off and discard the foam from the hot jam.
Canning Blackberry Jam
Submerge the canning jars in boiling water for 10 minutes to sterilize them. Wash the lids and rings in hot water. Ladle the blackberry jam into the jars, allowing about for about 1/4 inch of head space at the top of each jar. Wipe away any jam from the mouths of the jars. Attach the lids and rings. Process the jam jars in a boiling-water canner for 10 minutes or 15 minutes in altitudes above 6,000 feet. Remove the jars and allow them to cool for 24 hours. Reprocess improperly sealed jars. Store the jars in the pantry for up to one year. Once opened, refrigerate the jam at 40 degrees Fahrenheit or below. Refrigerated jam will last for at least a month. If the jam has visible mold or smells bad, throw it out.