Also known as tomorrow's leaf, ashitaba (Angelica keiskei) is a short-lived perennial herb native to the coasts of Japan. The edible plant is well known in Japan and the Philippines, where it is made into tea, noodles and candies. Somewhat uncommon as a garden plant, ashitaba may be difficult to find in nurseries.
Ashitaba grows as a perennial in U.S. Department of Agriculture plant hardiness zones 7 through 10. It will grow in coastal gardens or those that get salt spray. For best results, plant ashitaba in a deep, fertile soil in full sun or dappled shade. Water the plant regularly to keep the soil consistently moist, but not waterlogged. You can improve moisture retention in the soil by mixing in 2 to 3 inches of leaf mold, compost or fine pine bark to the soil before planting. In good growing conditions, ashitaba may grow up to 4 feet tall.
Divide and Conquer
Ashitaba generally blooms during its second year, producing seed before it dies. If your plant produces side shoots, divide them and plant them in the garden or a small pot to form new plants, or remove them to prevent the plant from flowering and going to seed. Its flowers attract beneficial insects. Harvest the leaves by removing one stem and leaf at a time, ideally early in the morning. Dry the leaves before storing them, as you would with other herbs. Members of the Angelica family contain furocoumarins. After handling ashitaba, some people may have increased skin sensitivity to sunlight, which may cause dermatitis. Check with your doctor if you plan on incorporating ashitaba into your diet.
Keeping the Balance
Ashitaba does best when fertilized. In early spring, fertilize the soil around the plant with a balanced 10-10-10 fertilizer. Thoroughly mix 1 ounce of fertilizer with 1 gallon of water for every 10 square feet. You can use a hose-end sprayer, backpack sprayer or watering can to evenly apply fertilizer to the soil. Gently agitate the sprayer as you work to keep the contents mixed. Follow label instructions carefully and keep the fertilizer stored away from children. If you get any in your eyes, flush it out with water and call your doctor.
If you can't find plants at the nursery, consider growing ashitaba from seed. Use fresh seeds for the highest germination rates. Sow the seeds on top of the soil in a cold frame. Once the seedlings are large enough to handle, plant them in 4-inch pots filled with a good quality potting mixture. Use pots with drainage holes. Once the young plants are about the size of your fist, move them to the garden. You can also grow ashitaba in 1-gallon pots with drainage holes.