Slow Cooker Tomato Jam

Prep Time

15 Minutes

Prep Notes

Savor late-season summer tomatoes with this jam! Savory jam may be new to you, but when you're craving tomatoes and the tastes of summer in the middle of winter, this jam hits the spot. It's great on toast and topped with eggs, or makes a great topper on mashed potatoes. Get creative!

Cooking Time

4+ hours


5 1/2+ cups


4 to 5 pounds of organic tomatoes (any variety)
1 organic lemon, seeds removed
2 tart apples
2T freshly ground ginger
1T coconut sugar, honey or maple syrup
Pomona's Universal Pectin or 2T agar agar 


Peel the tomatoes and roughly chop. Place them in the bowl of your slow cooker. Core, peel and dice the apples, and add them to the slow cooker. Keeping the peel on, dice the lemon and add that to the slow cooker, too. Next sprinkle in the ginger, coconut sugar and salt and stir. 

Cook on high for four hours, or low for eight. Adjust sugar and salt to your tastes. Once everything is nice and soupy and cooked down, add the pectin to the package instructions, or sprinkle in the agar agar. Stir and cook about an hour longer.

Set a large pot of water on the stove, on high, and bring to a low boil. This is where you'll process the jam jars. Working in batches, quickly blitz the mixture in a blender to smooth out, but leave a few chunks. Repeat with remaining mixture. 

Now, you're going to process the jam--this means getting it ready to become shelf-stable. Firstly, you'll want to place your jars, rings and lids in the water bath to sterilize for a few minutes. (Read this for more comprehensive instructions.) Remove the jars from heat, then fill the jars with the hot mixture, leaving a little room at the top. Clean the rim of the jar if any spilled. Place the lid on top, then lightly screw on the ring. Repeat with remaining jars. 

Place the filled jars into the hot water bath and process for about 10 minutes. Carefully, remove from the water and allow to cool so you can handle them. As the mixture cools, the lid will adhere and a delightful popping noise should happen. To test if the lead is sealed, lightly push down on the lid. If it does not give, the lid is sealed. If a lid does not seal, the jam will not be safe to store and should be placed in the fridge to eat soon. (Don't worry, though, it's still edible!)

As the mixture cools, the pectin will work its magic and the mixture will thicken. The sealed jam jars can stay in your pantry for a long time!