Culture
Winter hardy to USDA Zones 6-9 where this plant is easily grown in rich, deep, medium moisture, well-drained, sandy-limey loams in full sun to part shade. Plants tolerate a variety of soil types. Best performance occurs with consistent moisture during the growing season. Perennial plants are easy to propagate by division. This perennial bunching onion can be harvested year round in mild winter climates. It infrequently self-seeds, but clumps will spread slowly in the garden. In cold winter climates north of Zone 6, this plant is typically grown as an annual. When grown as an annual, sow seeds in early spring for summer use. Plant 1/4” and 1/2” apart and 1/2” deep. Provide regular shallow cultivation to reduce weed competition.
Noteworthy Characteristics
Allium fistulosum, commonly called spring onion, Welsh onion, or Japanese bunching onion, is a clumping, slowly-spreading, evergreen perennial onion that is primarily grown as a vegetable for harvest of its tasty onion-flavored leaves. Elongated underground bulbs are barely thicker than the plant stem (some characterize this species as being “bulbless”). Hollow, leafless, blue-green flowering stalks rise to 24-36” tall, each stalk being topped by a globular terminal umbel (to 3” diameter) containing tiny, yellowish-white, 6-tepaled flowers. Each umbel typically sports 50-100 flowers which bloom from late May to August. Hollow, basal green leaves are linear with entire margins, parallel venations and glabrous surfaces.
This bunching onion was developed in Asia from a wild relative native to China. It was brought to Europe in the 17th century. The original Chinese plant may be extinct in the wild. This onion has been extensively cultivated since ancient times. It has escaped gardens and naturalized in Alaska and in parts of Canada and the northern U.S.
Genus name comes from the classical Latin name for garlic.
Specific epithet comes from the Latin word fistulosus meaning hollow in reference to the stems and leaves.
Common name of Welsh onion does not refer to the country of Wales, but is derived from the German word walsch meaning foreign.
Problems
No serious insect or disease problems. Bulb rot may occur in overly moist soils. Slugs attack young plants. Mildew, rust and leaf spots may appear. Watch for onion maggots and thrips.
Uses
Widely used as a food additive in salads, garnishes, soups, stews, stir fry and Chinese cooking. Also serves as a chive/leek substitute. May be grown in herb gardens and vegetable gardens where the young leaves and bulbils may be harvested for food. Leaves are tasty when young, but are not ornamentally attractive. Flowering stalks are ornamentally attractive when flowers are in bloom.