Clean, wash and cut the rhubarb into small pieces. Wash lemon balm, shake dry, pluck leaves from stalks and chop finely. Put the rhubarb and jam sugar in a large pot. Bring everything to a boil over high heat, stirring constantly, and let it boil for 3-4 minutes
Take the pot off the stove. Fold in grated coconut and lemon balm. Pour mixture into prepared glasses. Close well, turn them over and let them stand on the lid for about 5 minutes. Store jam in a dark place