Makes 8 cups
1/4 cup lemon juice
5 1/2 cups crushed strawberries (about 3 quart boxes strawberries)
1 package powdered pectin
7 1/2 cups sugar
To prepare fruit. Sort and wash fully ripe strawberries; remove stems and caps. Crush berries.
To make jam. Measure crushed strawberries into a kettle. Add pectin and stir well. Place on high heat and, stirring constantly, bring quickly to a full boil with bubbles over the entire surface. Add sugar, continue stirring, and heat again to a full bubbling boil. Boil hard for 1 minute, stirring constantly. Remove from heat; skim.
From USDA #56