Rhubarb, Cardamom & Black Locust jam

Notes: Tart and surprisingly flowery jam with a hint of spice.

Serving ideas: Delicious in breakfast yoghurt, added to salad dressings and asian dipping sauces, and on your classic croissant – with or without butter!

History: The flowers from the Black Locust tree grow in gracious, white drooping clusters, and impart a sweet, wonderfully floral aroma. Also called “False Acacia”, they are actually the flowers that bees make “Acacia Honey” with (I know, confusing right?!)

They are found widely in Berlin and in the spring I go foraging for the flowers which I add to this jam, giving it a characteristic flowery twist. With the tartness of local farmers’ Rhubarb and the peppery, minty spiciness of green cardamom, it is a combination which inevitably takes you back to Berlin’s early spring vibe.

This jam is especially floral with a zing to it that raises the flavours to an unexpected yumminess! I finished the “taster” jar within the week.  This is the recipe I made which yielded 20x 220ml pots, so do adjust accordingly. Don’t worry too much about what quantity of which flowers you have, although I recommend having a majority of Black Locust, as it gives the jam its particular flowery tones.


  • 9 cups Flower Water (see below)
  • 1 kg Rhubarb, chopped
  • 4 cups pear juice
  • 6 1/2 cups sugar
  • Seeds from 12 green cardamom pods, lightly crushed
  • Juice of one lemon
  • 13 tsp Agar Agar

Flower waters. Prepare 24 hours in advance of cooking.

  • 4 cups Black Locust & Rose flowers – only the petals, remove green parts + 6 cups hot water
  • 3 cups Elderflower blossoms + 4 cups hot water

For the flower waters, I put the petals in a large glass bowl, boil the water, and pour the water over the flowers, then cover and let stand overnight to infuse the flavours before draining (hence you lose some of the water volume). I made the Black Locust and Elderflower waters separately, so I can’t say if there would be a difference doing them together. I find Elderflowers can be overpowering, and wanted to smell the Black Locust before making the jam in order to have a more accurate grasp of the flavours!

Making the jam

Take 9 cups of flower water, add 4 cups of pear juice and 6 cups of sugar,  Squeeze in half a lemon and bring to the boil in a thick-bottomed pan, let simmer for 30 minutes.

Heat another pan on low, put the cardamom seeds and dry-roast them for 10 minutes. Add the Rhubarb, lemon and half a cup of sugar on low heat and bring to a simmer. Simmer until the mixture becomes a jam.

Put the Agar agar in a small bowl and add about a cup of the hot Flower Water, stir to dilute. Mix into the flower water, add the rhubarb jam, and simmer for another 10 minutes.

Pour into sterilized jars and allow to cool upside down.

 The Agar agar can settle at the bottom, so it’s a good idea to stir the mixture constantly between pouring into the jars, so as to avoid some pots being too jellified whilst others remain too liquid!

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