Many large-leaved herbs can be loosely bunched, their stems tied with a string, and hung head down in a darkened and well-ventilated room, such as an attic or shed, until it’s time to store them.
This will take from three days to several weeks, depending on the particular herb. A steady temperature of 70 degrees is ideal.
Since one of the benefits of home drying is color retention, be sure to cover any windows in your drying area. Direct sunlight will bleach the crop quickly. Another way to block the sunlight is to cut out the bottom of a shopping bag and suspend the herbs within. This will also discourage dust from settling as the herbs dry.
– From The Forgotten Art of Growing, Gardening and Cooking with Herbs, by Richard M. Bacon (Yankee Books, 1972)