Rinse six 1-cup plastic containers and lids with boiling water. Dry thoroughly. In a large bowl, thoroughly crush all of the berries. Stir in sugar; let stand 10 minutes, stirring occasionally.
Combine pectin and lemon juice; add to fruit, stirring constantly until sugar is dissolved, about 3 minutes.(A few sugar crystals may remain.)
Immediately fill all containers to within 1/2 in. of tops. Wipe off top edges of containers; immediately cover with lids. Let stand at room temperature 24 hours.
Jam is now ready to use. Refrigerate up to 3 weeks or freeze extra containers up to 12 months. Thaw frozen jam in refrigerator before serving.
Editor's Note: If saskatoon berries are not available in your area, add an extra cup of one of the other berries.