Sterilize 2 1-pint jars, or a collection of smaller jars by submerging into a pot of boiling water. Drain and set aside to dry.

Place rhubarb, sugar, ginger and 1 cup of water in a saucepan and bring to a simmer over medium-low heat. Stir occasionally and skim white foam from top as syrup begins to thicken, about 15 minutes.

Strain rhubarb over a bowl and return syrup and ginger to saucepan. Continue to simmer syrup until very thick, about 7-10 minutes. Remove from heat and discard ginger. Stir rhubarb into syrup and cool for 5-10 minutes.

Pour jam in jars, seal, and let stand at room temperature to set. Store in refrigerator for up to 1 month.