In a large saucepan, combine the rhubarb, sugar, lemon juice, and grated ginger.
Place the saucepan over medium heat and stir until the sugar has dissolved.
Bring the mixture to a boil, then reduce the heat and let it simmer for about 30-40 minutes, stirring occasionally, until the rhubarb has softened and the jam has thickened.
Remove the saucepan from the heat and let the jam cool for a few minutes.
Transfer the jam into sterilized jars and seal them tightly.
Before placing the jam in the refrigerator, let it cool completely.