Gently rinse the excess salt from the cherry blossoms. Add the blossoms to ½ cup of hot water and steep for 15 minutes. Strain and save the infused tea to use later. Gently place each flower in the “jelly mold”.
Steep the hibiscus tea in 1/3 cup of hot water for 15 minutes. (optional)
Bring 5½ cups of water to a full boil in a saucepan over medium heat. Add agar agar powder to the boiling water, reduce heat and stir until it dissolves completely (about 1 minute).
Add the cherry blossom tea and a small amount of the hibiscus tea to the saucepan. Stir for another 10 seconds. (Adjust the amount of hibiscus tea according to how pink or red you want the tea jelly to be.)
Pour the mixture into the jelly molds. Adjust the position of the flowers as needed. Allow to cool, then refrigerate until set and serve chilled.