Although we picture licorice as being black, in candy whips or lozenges, it actually originates as a much sunnier color. The roots from which the flavoring is harvested are yellow. Native to the Mediterranean and Asia where it can reach 5 feet in height, licorice (Glycyrrhiza glabra) will probably only attain about 3 feet in colder climates. An invasive vetch-like plant, it can send out roots 3 to 4 feet deep and runners 25 feet long, and is considered hardy in U.S. Department of Agriculture plant hardiness zones 6 to 11.
Scarify licorice seeds before planting them. Roll up a piece of sandpaper and place it inside a glass jar, where it should unroll to hug the sides of the jar. Drop the seeds inside the jar, cap it and shake it, until the sandpaper scuffs the hard coating on the seeds.
Dump the seeds from the jar into a container of water. Allow them to soak for 24 hours, during which time they should swell up a bit. If they don't, return them to the shaker for some more sanding.
Fill square 4-inch pots to within 1/2 inch of their tops with moist seed-starting mix. Sow the licorice seeds 1/4-inch deep and 1-inch apart -- planting nine seeds per pot. Cover the pots with plastic wrap, keep them at 68 degrees Fahrenheit, and expect sprouts in two to three weeks.
Remove the plastic wrap after the seeds begin germinating and place the pots in a greenhouse or under a grow light, where the temperatures remain in the 60s Fahrenheit. Keep the mix damp until the seedlings each have four leaves, after which they should be transplanted into individual pots of potting soil. For the best results use 4-inch-diameter tree pots that provide plenty of depth -- 10 to12 inches -- for long roots.
Move the pots outdoors in the spring after your last frost date, gradually exposing the seedlings to full sun, but don't expect them to grow more than 9 inches tall their first year. In USDA zones 10 and 11, you can set the seedlings in the ground in autumn.
Keep the plants in their pots all summer in USDA zones 6 to 9, and return them to a greenhouse or cold frame for their first winter. Transplant the seedlings into the garden in early summer of the following year. Select a location in full sun that has very deep, rich and sandy soil with no rocks.
Set the plants 3 feet apart. Water them often until they are established, after which they shouldn't need much irrigation. Sprinkle slug bait around the plants, and renew it after rains.
Snip off any flower stalks that form, because licorice roots are best if harvested before the plant blooms. Since legumes "fix" their own nitrogen, they need little fertilization, but it's a good idea to mulch them after they die back in the fall with composted manure.
Items you will need
- Licorice seeds
- Glass jar with lid
- Square 4-inch pots
- Seed-starting mix
- Plastic wrap
- Greenhouse or grow-light
- 4-inch tree pots
- Potting soil
- Cold frame (optional)
- Watering can
- Slug bait
- Composted manure
- Don't harvest licorice roots until the plants are at least 3 years old. Dig them in the fall after their tops die back, remove only the largest roots and replant the others. Slice the harvested roots into strips about 8 inches long and 3/4 of an inch thick before drying them.
- Licorice can be harmful to persons with certain health conditions, so research the plant thoroughly before consuming it.
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