In a medium size sauce pan combine the sugar and water and bring to a brisk simmer. Once simmering, reduce the heat and stir to dissolve the sugar. Remove from the heat and add the chamomile flowers and lemon zest. Once cool refrigerate for at least 24 hours and up to 2 days. Strain the syrup through a fine mesh strainer into jars or bottles, discard chamomile flowers, and store in the refrigerator for up to 1 month.