St. Germain is made from liqueur flavored with Elderflower.
As soon as the flowers reach the collection station, they are immediately macerated using a “secret” family technique, which is said to give them the best flavor, while not being too bitter, too sweet or as inconsistent as other methods, such as freeze drying or pressing the flowers.
These are then infused into eau-de-vie (Unaged Brandy), although this part of the process is not well elucidated by the company. The spirit is then sweetened lightly, but is said to contain less sugar than a typical liqueur. The liqueur is then bottled.
Since st. germain is made without any preservatives, it is recommended that you use the bottle within 6 months of opening.