Recipe yields 10 half-pint jars.

Prepare for Canning

• Prepare the calcium water: Combine ½ teaspoon calcium powder (from the small packet in the box of Pomona’s pectin) with ½ cup water in a small jar. Screw on a lit and shake until well-combined. You'll have more than you need for this recipe. Store the excess in the refrigerator for use in making additional jam or jelly recipes.
• Wash the jars you'll use, making sure each is clean and free of nicks in the rim, which could impede sealing.
• Wash the lids and rings in hot soapy water. (If you're using non-Ball brand lids, prepare as suggested by manufacturer.)
• Place empty jars in a canning pot or large stock pot with enough water to cover by an inch or two, cover pot, and set on high heat. It can take awhile for the water to heat, so get it started before you begin making the recipe.

Make the jam

• Prepare persimmons (see notes); measure 8 cups of pulp into a large pot. Add the prepared calcium water and lemon juice; stir to combine well.
  8 cups persimmon pulp, 8 teaspoons calcium water, 1 cup lemon juice
• In a separate bowl, combine the sugar with the pectin powder (the large envelope) until thoroughly combined. Stir in spices.
  1 1/2 cup sugar, 4 teaspoons pectin powder
• Bring mashed persimmons to a full boil. Add sugar mixture, stirring vigorously for a couple of minutes to dissolve the pectin. Return to a full boil and remove from heat. Stir in flavorings.
  1 teaspoon ground ginger, 1/2 teaspoon ground nutmeg, 1 teaspoon ground cinnamon

Canning persimmon jam

• Remove the empty jars from the canner, draining the water back into the pot.
• Ladle hot jam into half-pint or pint jars to within a quarter inch of the rim. A canning funnel makes this easy. or pint
• Wipe jar rims to remove any jam that may have spilled. A clean rim is essential to a good seal.
• Set jar lids in place. Screw bands on finger tight.
• Use a jar lifter to gently submerge jars into the hot water bath. Be sure to place a wire rack in the bottom of the pot to prevent the jars from sitting directly on the bottom. Water should cover the top of the jars by an inch or two. The water will cool somewhat in reaction to the addition of the jars. Return the water to a low boil and then set the timer.
• Process in a boiling water bath for 10 minutes. For higher altitudes, add a minute to the boiling time for every 1,000' above sea level.
• Check seals. Lids should be solid and pulled down tight. (if they flex and pop, the jar didn’t seal; put unsealed jars in the refrigerator and use those first).
• Remove rings and wash outsides of jars. Store in a cool, dry place.