Ingredients

  • 4 1/4 cups diced rhubarb
  • 4 1/4 cups sliced fresh strawberries
  • 2 tablespoons lemon juice
  • 2 (1.75 ounce) packages powdered fruit pectin
  • 1/2 teaspoon butter (optional)
  • 10 cups white sugar
  • 12 half-pint canning jars with lids and rings

Method

  • Place rhubarb, strawberries, lemon juice, fruit pectin, and butter into a large kettle over medium heat.
  • (Butter is optional but helps keep jam from getting too foamy).
  • Stir the fruit mixture to help the juice start to form, and add sugar, about 1 cup at a time, stirring constantly until sugar is dissolved and the juice is starting to simmer.
  • Turn up heat to medium-high, bring the mixture to a full rolling boil, and cook and stir for 1 minute.
  • Skim off any foam that forms.
  • Sterilize the jars and lids in boiling water for at least 5 minutes.
  • With a jelly funnel and a soup ladle, pack the jam into the hot, sterilized jars, filling the jars to within 1/4 inch of the top.
  • Run a knife or a thin spatula around the insides of the jars after they have been filled to remove any air bubbles.
  • Wipe the rims of the jars with a moist paper towel to remove any food residue.
  • Top with lids, and screw on rings.
  • Place a rack in the bottom of a large stockpot and fill halfway with water.
  • Bring to a boil over high heat, then carefully lower the jars into the pot using a holder.
  • Leave a 2 inch space between the jars.
  • Pour in more boiling water if necessary until the water level is at least 1 inch above the tops of the jars.
  • Bring the water to a full boil, cover the pot, and process for 5 minutes.
  • Remove the jars from the stockpot and place onto a cloth-covered or wood surface, several inches apart, until cool.
  • To help the jam set, don't move or touch the jars until cooled.
  • Once cool, press the top of each lid with a finger, ensuring that the seal is tight (lid does not move up or down at all).
  • Store in a cool, dark area.