Found this. Thought it might be useful to anyone out there about to come into a large number of blackberry plants. You know, if the hit comes through. I liked the simplicity of it – I imagine it’s how they talk in the countree.
You need:
Weight of blackberries and equal weight in raw sugar
A small amount of crushed apple and lemon juice – about one apple and a squeeze of lemon per 2 kg of berries (or you could probably substitute powdered pectin here).
Gently heat in pot (if you have about 10 kg jam it might take 3 hours). Keep heating and check that it’s ready using the spoon method – take a teaspoon of juice out of jam and cool to room temperature, jam is ready if juice doesn’t run off spoon. Bottle in boiled bottles.
EDIT: If you make 10kg of the stuff young lady I expect AT LEAST 3 bottles to be freighted to Brisbane post haste.
Or I could come help you make it and take ’em home myself. Whatever.
Sherdie 
We used to make blackberry jam a lot when I was a kid because our backyard had thousands off the things (they were a bit of a pest and painful if you ran into them). But that was down south. I wonder if blackberries grow in Queensland?
I prefer a Chuck Berry jam meself … with Bo Diddley. God that’s bad.*unplugs computer*
yup. everyone is helping in their own special way!I think the current exchange rate is 1kg blackberry jam to 1 tray of mangoes or equiv semi dried weight…..Havnt seen many mangofarmer mangos ’round these parts lately…….so you will just have to come and help me!hee hee.