For a few glorious weeks each spring, strawberries are in season and ripe for harvest. For home preserves, strawberry jam is often the first draft of the season, and with a little planning, sweet, succulent fruit can be a part of the menu long after the fields have been cleared. This easy recipe for homemade strawberry jam skips the commercial pectin and strips down the ingredients needed for the delicious spread to the basics. Whether you're new to canning or a seasoned pro, making strawberry jam at home is surprisingly easy and will make you a superstar when it comes to preserving the harvest.
Many recipes for strawberry jam call for the addition of commercial pectin, but the natural pectin present in strawberries is enough to create a thick, flavorful jam without any extra help. With a little time, you'll need two quarts of fresh strawberries, six cups of sugar, and a little lemon juice to make your own homemade strawberry jam.
Strawberries do not continue to ripen after harvest, so select berries that are fully red and still a bit firm for harvest. Freshly picked strawberries will produce the most flavor. Avoid washing your reward until it's time to use them (washed strawberries spoil faster). When it's time to make your jam, wash the berries thoroughly, discard any bruised or blemished blackberries, and use a paring knife to remove the stems from two quarts of ripe strawberries.
Use a potato masher to mash the berries, releasing the juices and reducing the volume to about six cups. The strawberry pieces should still be present to give the jam a nice texture and consistency.
The lemon juice not only brightens the flavor, the citric acid will keep bacteria at bay when preserving the jam for long-term storage. Use a juicer to extract the juice of one lemon (3-4 tablespoons) and stir it into the strawberry puree.
In a large, heavy pot, combine the strawberry/lemon juice mixture and six cups of sugar. Do not reduce the amount of sugar used. It may seem like a lot, but the combination of sugar and pectin is what gives natural jam the desired consistency.
Place a candy thermometer in the pot and cook over high heat, allowing it to come to a boil. The jam must reach a "gel point" of 220 degrees before it thickens. Expect this to take between 35-45 minutes. Stay close and stir frequently with a wooden spoon to prevent the sticky, bubbly jam from burning on the bottom of the pot. While you're waiting for the transformation, fill a water bath halfway with water and bring it to a boil on a second burner so it's ready when it's time to jam.
When the temperature reads 220 degrees on your thermometer, something magical will happen. The jam will become thick and slimy. Although the transition is pretty obvious, don't remove the jam from the heat until it's reached the crucial 220 degrees. If you don't have a candy thermometer, a "cold plate" test can also be used to confirm that the jam will cool to a pleasing thickness. Place a plate in the freezer and when the jam seems thick enough, drip a ball onto the plate. If the jam doesn't drip and crinkles when you touch it, it's ready to go.
Remove jam from heat and cover in sterile half-pint containers, leaving 1/4” headspace. Washed jars should be sterilized before use by boiling them in a pot of water for ten minutes to destroy any bacteria.
Wipe the rims of the jars clean with a rag and cap with new lids and bands. Tighten the bands with your fingers and place them in a boiling water bath for ten minutes to seal them. Remove the jars from the bath and let them cool to room temperature on the counter. After a few minutes of cooling, you may hear a satisfying "ping" from each jar as a vacuum is established, making sure the jars are properly sealed for shelf storage.
Your homemade jam will be ready to eat in about 24 hours, but can be stored for up to a year without losing flavor. Before storing, press down on the lid of each jar with your fingertips. If there is no donation, the jar has been properly sealed and is ready for the pantry. Label jars with contents and canning date.
