There's something about a backyard plum harvest that demands you do something with it. The trees don't ask whether you're ready — they just ripen. This jam is the answer for most of the fruit.
It's a straightforward put-up: plums, sugar, lemon juice, and time. The cinnamon and vanilla are optional but recommended. The result keeps for a year on the shelf, gets better on toast after about two weeks, and — if you hold back a pound or two before the sugar goes in — becomes the base for Plum Simple Syrup and the Plum Bourbon Sour.
- 5.6 lb pitted plums
- 3.75 lb granulated sugar
- Juice of 2 lemons, about 1/4 cup
- 1 cinnamon stick (during cooking)
- 1 tsp vanilla extract (after cooking)
This combination gives you a rich, balanced plum flavor without pushing into candy-sweet. The cinnamon is subtle enough that you won't identify it — you'll just notice the jam tastes a little more like itself.
Step 1 — Prepare the Fruit
- Wash plums thoroughly under cold water.
- Pit and cut into quarters or rough chunks. No need to peel — the skins add body and color.
- Add to a large heavy-bottomed pot or Dutch oven.
Step 2 — Cook the Fruit
- Add lemon juice and cinnamon stick if using.
- Cook over medium heat, stirring occasionally.
- After 15–20 minutes the fruit should be fully soft and beginning to break down. Press gently with your spoon to help it along.
Step 3 — Add Sugar
- Gradually stir in sugar. Take your time — rushing this can cause scorching on the bottom.
- Stir until the sugar is fully dissolved before you increase the heat.
- Bring to a full rolling boil that can't be stirred down.
Step 4 — Cook to Jam Stage
- Boil vigorously, stirring frequently. The mixture will spit — keep the heat managed and stay close.
- Continue cooking 20–35 minutes. The range depends on how much natural moisture your plums had.
- Skim foam from the surface if desired. This is cosmetic — it doesn't affect the flavor or safety of the jam.
Step 5 — Test for Doneness
- Before you start cooking, put a small plate in the freezer.
- When you think the jam might be done, drop a small spoonful onto the cold plate.
- Wait 30 seconds, then push the edge with your finger.
- If the surface wrinkles and holds its shape, it's ready. If it runs, give it another 5 minutes and test again.
Finishing the Jam
- Remove from heat and pull out the cinnamon stick.
- Stir in vanilla extract, almond extract, or bourbon if using. Adding these off-heat preserves more of their flavor.
- Let stand 5 minutes, then stir gently before filling jars. This helps distribute the fruit evenly.
Water-Bath Canning
- Ladle hot jam into hot sterilized jars, leaving 1/4-inch headspace.
- Wipe jar rims clean with a damp cloth. Any residue on the rim can prevent a proper seal.
- Apply lids and bands fingertip tight — firm but not cranked down.
- Process half-pint or pint jars in a boiling water bath for 10 minutes.
- Remove jars and let cool undisturbed for 12–24 hours. You'll hear the lids pop as they seal.
Storage
Up to 1 year
Cool, dark location. Check seal before opening.
3–4 weeks
Use a clean spoon every time.
Up to 1 year
Leave 1/2-inch headspace in freezer-safe containers.