Couldn’t resist that huge pallet of late-season berries? Capture their essence by making jam with these tips from Rebecca Courchesne, coauthor of The Art of Preserving (Williams-Sonoma, 2010).

Get the right stuff

Use an extra-large boiling-water canner with a tight lid and a removable rack, allowing for good water circulation. Purchase canning jars with screw bands and rubber-seal lids. All are available in kitchenware stores or markets.

Pick your fruit

A mix of slightly underripe and just-ripe berries makes the perfect balance for flavor and consistency.

Cook gently

In a large nonreactive pot, bring 12 cups mixed organic berries, 3 cups natural cane sugar, and 3/4 cup fresh lemon juice to a gentle boil. Reduce heat to medium and cook, stirring often, until thickened, about 15 minutes. Don’t vigorously boil or overcook the jam, which may cause the natural pectin (thickening agent) to break down.

Prep and fill

Sterilize jars, lids, and screw bands in the dishwasher or wash by hand; keep jars warm and lids in simmering water until ready to use. Ladle hot jam through a funnel into one hot, clean jar, leaving 1/4–1/2 inch of space at the top. Wipe rim clean with a damp towel, top with a dried lid, and screw on band securely but not too tight. Repeat with remaining jars and jam.

Process

Immediately place filled, sealed jars on canner rack in hot water. Cover by at least 2 inches of water. Cover pot, return water to boil, and process for 10 minutes (add 1 minute for every 1,000 feet above sea level). Lift jars out of water and space apart on a towel to cool.

Test seals

When completely cool, test seals by pressing tops; they should be rigid, taut, and slightly indented. (If not, you can still eat the jam; refrigerate for one month.) Store well-sealed jars in a cool, dark place for up to a year. Makes 6 half-pint jars.