Recipe yields 9-10 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

• Measure mashed strawberries into a large pot along with 4 teaspoons of the prepared calcium water.
  8 cups strawberries
• In a separate bowl, combine the honey (or sugar) with 4 teaspoons pectin powder (the large envelope) until thoroughly combined.
  1 cup honey, 1 box Pomona brand pectin
• Bring strawberries to a full boil. Add sweetener, stirring vigorously for a couple of minutes to dissolve the pectin. Once returned to a full boil, remove from heat.

Canning strawberry jam

• Ladle hot strawberry jam into half-pint jars. This jam requires a quarter-inch headspace, which means you'll ladle jam to within a 1/4" of the top of the jar. A canning funnel makes this easy.
• Wipe jar rims to remove any jam that may have spilled. A clean rim is essential to a good seal.
• Place lids on the jar rim and screw bands on finger tight.
• Use a jar lifter to gently submerge jars into simmering water in canning pot with a canning rack in the bottom of the pot. Water should cover the top of the jars by an inch. 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. 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 jars of jam in a cool, dry place for up to a year.