Clean and wash the rhubarb and cut into pieces 1-2 cm long. Mix with the preserving sugar and let it steep for about 2 hours.
Put the saucepan on the stove, stir in the lemon juice and heat everything. Let simmer for approx. 4-5 minutes. Stir in the desiccated coconut while it cooks.
Pour the jam into jam jars, close them and then let them cool.
For me this amount resulted in approx. 7 glasses with 300 ml each. Depending on the size of the jam jars, this number can of course also vary.