Wash and rinse jars in hot water.
Prepare calcium water. Put 1/2 teaspoon calcium powder and 1/2 cup water in a lidded jar. Shake well.
Prepare fruit. Measure 8 cups of chopped rhubarb and 12 cups of destemmed strawberries.
Add the juice and peel of two lemons.
Add strawberries, rhubarb, lemon juice, lemon peel, and calcium mixture into a large pot.
Open pectin packet and add half the packet to 2 cups of sugar and mix together.
Pour sugar mixture into the pot and bring everything to a boil. Stir vigorously until the pectin mixture dissolves.
Fill jars to 1/4″ of top. Wipe rims clean. Screw on 2-piece lids. Put filled jars in boiling water to cover. Boil 10 minutes.
Remove from water and let cool.
Make sure to check seals before storing!!