Licorice, also known as Glycyrrhiza glabra, is a member of the pea family and is native to southern Europe and portions of Asia. Commercial growers usually propagate licorice by root cuttings, but it also can be grown from seed. Licorice seed can be difficult to grow, because it requires some special treatment to germinate. Some of the best tips for planting licorice seed are presoaking the seeds, planting them where they will receive the proper amount of sunlight and using two types of special treatments on them, called stratification and scarification.
For outdoor growing, plant licorice seed in spring or summer. Always presoak the seeds for 24 hours in water at about 68° Fahrenheit (20° Celsius). Plant the seed in a location that receives partial shade to full sun, with moist, well-drained soil that has a high percentage of organic matter and a slightly acid potenz hydrogen (pH) level. Cover the seeds lightly with soil, and keep the area moist but not wet.
Licorice seed also can be germinated indoors in sterilized soil, which reduces the risk of contamination from fungus or bacteria. In this case, plant the licorice seeds in individual pots or flats that have been filled with a mixture of potting soil and peat moss. Transplant them outside after the risk of frost or to larger pots after they have developed strong root structures and stems.
The licorice plant germinates poorly and unpredictably from seed. Most licorice seeds that are planted never germinate. Those that do germinate will produce tiny roots and leaves within one to two weeks, growing slowly thereafter.
Some special treatments can increase the percentage of licorice seeds that germinate. Stratifying and scarifying licorice seeds helps break through their thick outer coating. Stratification involves placing the seeds in plastic bags full of moist peat moss or wet paper towels for two to three weeks. Scarification involves scraping part of the seed with the tip of a knife. Licorice seeds are very tiny and can be difficult to scarify.
After germination, licorice seed produces a perennial plant that grows up to 4 feet (about 1.2 m) tall. In the summer, it develops light blue flowers. The fruit is about 1 inch (about 2.5 cm) long and contains several dark, oblong seeds. Licorice is hardy in climates where the minimum temperature is 0° Fahrenheit (minus-17.8° Celsius) or higher but can die after frost in colder climates.