I consider lemon balm an herb garden essential. The lemony-scented leaves are delicious dried and used in teas. As a medicinal, lemon balm has powerful anti-viral properties that validate its usage for anything from the flu to herpes. Start in early spring and transplant after the last frost. Lemon balm will continue to live, with winter die-back, for many years and is easily spread in the garden. Perennial.