Prepare a boiling water bath canner and four pint jars.
Pit and roughly chop the plums. Place them in a low, wide, non-reactive pan and add the sugar and ginger.
Place pan over medium-high heat. Bring to a boil and cook, stirring regularly, until the fruit softens and had reduced by about half.
When the sauce is finished cooking, use an immersion blender to puree it smooth.
Funnel jam into prepared jars. Wipe rims, apply lids and rings, and process in a boiling water bath canner for 10 minutes.
When time is up, remove jars from canner and let them cool on a folded kitchen towel.
When jars are cool enough to handle, check the seals. All sealed jars are shelf stable for up to one year. Any unsealed jars should be refrigerated and used promptly.