Cover with a clean dishtowel or cheesecloth and let the mixture sit at room temperature for 48 hours, stirring at least twice a day. By the end of these two days, you should see signs of fermentation: the top of the liquid will look frothy and bubbly, especially when you stir it. If the liquid is remains completely still after 48 hours, add a teaspoon of water kefir grains and wait another 48 hours, stirring occasionally, before proceeding to the next step. (the room temperature and the amount of beneficial yeast on the flowers plays a part in this process which is why you may or may not need the kefir grains) In most cases I like to add them any way, especially in the colder months).