A tincture is an alcohol and water extract which is used when plants have active chemicals that are not very soluble in water, and/or when a larger quantity is prepared for convenience and wanted for longer term storage. Many properly prepared plant tinctures can last several years or more without losing potency. The percentage of alcohol usually helps determine its shelf-life: the more alcohol used, the longer the shelf life.
To prepare a tincture with a shelf-life of at least one year, plan on using a minimum of 40% alcohol. Use a clean glass bottle or jar with tight fitting lid or cork. Use a dark colored bottle or plan on storing the bottle out of the sunlight. When working with dried plants, use two ounces of plant material (cut or powder) for every 8 ounces (1 cup) of liquid. Seal the container and store at room temperature away from direct sunlight. Shake the bottle/jar at least once daily while allowing it to soak for at least two weeks (larger woody cut herb pieces may need to soak for 4 weeks). At the end of two weeks, filter the tincture through a strainer to remove the plant parts (pressing hard on the plant material to get as much liquid out as possible) and pour into a fresh clean glass container and seal.
Since this method uses a higher ratio of plant to liquid and helps concentrate the chemicals through the use of alcohol, dosages needed for tinctures are usually much less than infusions and decoctions. Average dosages for tinctures are about 1-2 milliliters (about 30 to 60 drops) two to three times daily. The tincture can be placed directly in the mouth for immediate absorption, or placed in a small amount of water or juice.