VegetableOnion
Ishikura Winter Long Onion
Ishikura Winter Long is a Japanese bunching onion bred for cold climates and mild flavor, delivering tender, hollow stalks ready to harvest in just 40 to 49 days. Hardy from zones 2 through 9, this heirloom thrives as both an annual and perennial, growing 14 to 20 inches tall with a vigorous constitution that shrugs off frost and pests alike. Whether you're harvesting fresh green onions for spring cooking or letting plants overwinter for early summer harvests, this variety brings reliable productivity and delicate onion flavor to gardens across North America.
Photo © True Leaf Market
Growing Conditions
USDA Zone
2-9
Sunlight
Full Sun
Water
Moderate
Soil
Well-drained, Fertile Loam; Tolerates Moderate Fertility
Growth Stats
20 in
Height
Spacing
2
Plant Profile
Sunlight
Full Sun
Water
Moderate
Zones
2-9
Size
20in H x ?in W
Growth
—
Care
High
Hover over chart points for details
Highlights
The standout feature here is the combination of extreme cold hardiness and speed to maturity. Bred specifically to handle harsh winters, Ishikura Winter Long tolerates frost that would kill conventional bunching onions, yet it reaches eating size in just six to seven weeks. The hollow stalks have a notably mild, clean onion flavor that works beautifully in raw applications where milder specimens shine. Its ability to regrow after cutting and to succeed as a perennial in many climates makes it exceptional for gardeners who want a long-season harvest from a single planting.
Common Uses
Harvest the tender green stalks as fresh bunching onions for salads, garnishes, and stir-fries, where their mild flavor and tender texture shine brightest. Use them chopped over soups, scattered across noodle dishes, or grilled whole as a side vegetable. The mild character makes them excellent for eating raw, where harsher onion varieties would overpower. Home cooks also appreciate them as microgreens, a suggestion reflected in the catalog description for tender, delicate harvests in small spaces.
Growing Timeline
No timeline data available yet for this variety.
Care Instructions
Start Indoors
Start seeds indoors 4 to 6 weeks before your last spring frost in standard seed-starting mix kept at 65 to 70 degrees Fahrenheit. Sow seeds at the depth specified below and maintain consistent moisture until germination. Transplant seedlings outdoors after hardening off once nighttime temperatures stay above 40 degrees Fahrenheit.
Transplant Outdoors
Harden off seedlings over 7 to 10 days by gradually exposing them to outdoor conditions. Transplant once soil can be worked in spring and nighttime temperatures remain above 40 degrees Fahrenheit. Space plants 2 inches apart with 15 inches between rows, burying them at the same depth they were growing in containers. Firm soil gently around each plant and water well.
Direct Sow
Direct sow seeds in spring once soil is workable, or in late summer for fall and winter harvest. Sow thinly along rows 15 inches apart and thin seedlings to 2 inches spacing as they develop. Keep soil consistently moist until germination and throughout the season.
Harvesting
Begin harvesting outer stalks once plants reach 6 to 8 inches tall, typically 4 to 6 weeks after planting. Cut stalks at soil level with a sharp knife or scissors, leaving the white basal portion in the ground to regenerate. Plants regrow from the base, producing multiple harvests from a single planting throughout the season. For maximum tenderness, harvest in the morning after dew has dried. In mild climates, continue harvesting through winter when growth slows, and plants often send up fresh growth in early spring.
Growing Calendar
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Companion Planting
Pests & Diseases
Ecology & Traits
Edible
Scientific Classification
Allium fistulosum
Family
Amaryllidaceae
Genus
Allium
Native Status
L48 (I)AK (I)CAN (N)
History & Origin
“Ishikura Winter Long carries the name of its Japanese origin, where bunching onion varieties have been cultivated for centuries. This particular cultivar was bred and selected for cold hardiness and winter performance, reflecting regional Japanese horticultural traditions adapted to variable climates. The variety reached Western seed catalogs as growers recognized its superior frost tolerance and reliable yields, eventually earning recognition as both an heirloom and a cold-hardy workhorse. Its status as an open-pollinated, non-GMO cultivar means it has been preserved through careful seed saving across generations of gardeners.”