Katy's Organic Plum Jam

Source: Katy Gronowski, Preserves Contest Winner

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This jam won first prize in CUESA’s Summer Jam Preserves Contest at Jack London Square Farmers Market Harvest Festival on July 15, 2018.


5 cups pitted plums (Katy’s note: I used organic purple plums, which I picked before they were ripe)
5 cups organic sugar  
2 tablespoons lemon juice 
6 tablespoons pectin
1 tablespoon butter (optional)


1. Sterilize six 8-ounce jars and lids. You can sterilize by boiling the jars on a rack or by putting them in a preheated 250 degree oven for 20 minutes.

2. Pit the plums and cut them in half. Discard pits.

3. Put the plums in a pan with ½ cup of water and cook for 5 minutes over high heat, stirring frequently.

4. Put the plum mixture in a blender and pulse for 10 seconds. This breaks up the skins of the plums and gives the jam a nice, thick consistency.

5. Return the plum mixture to the pan. Add pectin and stir thoroughly. Add lemon juice and sugar.

7. Bring the jam to a rolling boil and allow it to boil for one minute. Add 1 tablespoon butter (if desired) to reduce foaming.

8. Pour jam into warm, sterilized jars leaving ¼ inch space at the top of the jar.

9. Allow jam to cool. Seal jars with lids and then sterilize filled jars. Jam may be stored for a year. Once opened, consume within a month.

Farmers Market Ingredients