Start with our step-by-step canning how-to.

Using a vegetable peeler, remove the zest from the lemons in wide strips, leaving the bitter white pith behind. Squeeze the lemon juice through a strainer into a large, wide saucepan.

Add 3 1/2 cups blueberries, the lemon zest, maple syrup and sugar and cook over medium-high heat, stirring, until the sugar dissolves, 6 to 7 minutes. Reduce the heat to medium and cook, stirring occasionally, until a candy or deep-fry thermometer registers 220 degrees F, 30 to 40 minutes (reduce the heat if the mixture is sticking to the pan). Remove from the heat.

Meanwhile, sterilize four 8-ounce canning jars and lids.

Return the blueberry mixture to medium-high heat. Bring to a boil, stirring, then add the remaining 4 1/3cups blueberries. Reduce the heat to medium low and simmer until those berries are tender but still hold their shape, 7 to 10 minutes.

Fill the jars with the blueberry mixture, leaving 1/4 to 1/2 inch headspace, then seal and process.

Photograph by Charles Masters