Allium cepa 'Superstar', Superstar Onion
1 / 2
Annuals

Allium cepa 'Superstar'

Superstar Onion

AmaryllidaceaeAsia

At a Glance

Typeannual
Habitupright
Foliagedeciduous
Height18-24 inches
Width4-6 inches

Growing Zones

USDA Hardiness Zones

3a - 9b
Zone 3a
Zone 3b
Zone 4a
Zone 4b
Zone 5a
Zone 5b
Zone 6a
Zone 6b
Zone 7a
Zone 7b
Zone 8a
Zone 8b
Zone 9a
Zone 9b
These zones indicate the coldest temperatures this plant can typically survive.
Frost Tolerancehardy

Key Features

Deer Resistant
Fragrant (strong)
Container Friendly
Maintenancelow

Overview

Allium cepa 'Superstar' is an exceptional storage onion cultivar that produces large, uniform globe-shaped bulbs with distinctive golden-bronze outer skins and crisp, white interior flesh. The bulbs typically mature to 8-12 ounces with excellent symmetry and multiple layers of protective papery scales that contribute to their outstanding storage capabilities. The plants develop hollow, cylindrical blue-green foliage that can reach 18-24 inches in height, with the characteristic pungent onion scent when crushed. When allowed to bolt, Allium cepa 'Superstar' produces tall flowering scapes topped with spherical umbels of small white flowers, though these are typically removed to encourage bulb development. This cultivar is particularly prized for its consistent performance, disease resistance, and remarkable ability to store for 8-10 months when properly cured, making it invaluable for year-round culinary applications.

Native Range

Allium cepa originates from the mountainous regions of Central Asia, particularly areas that encompass modern-day Afghanistan, Iran, Pakistan, and surrounding territories. Wild populations of the species can still be found in these harsh, arid mountain environments where the plant has adapted to extreme temperature fluctuations and limited water availability.

Suggested Uses

Allium cepa 'Superstar' excels in vegetable gardens, raised beds, and container growing where its uniform size and excellent storage qualities can be fully appreciated. Ideal for market gardening and commercial production due to consistent bulb characteristics. Perfect for companion planting alongside tomatoes, brassicas, and root vegetables. The long storage life makes it invaluable for home preservation and year-round culinary use in cooking, while the attractive foliage adds vertical interest to vegetable garden designs.

How to Identify

Allium cepa 'Superstar' can be identified by its notably large, perfectly globe-shaped bulbs with rich golden-bronze papery outer skins and firm, white flesh arranged in distinct concentric layers. The foliage consists of hollow, cylindrical leaves that are distinctly blue-green in color and reach 18-24 inches tall, emerging directly from the bulb base. The bulbs are exceptionally uniform in size and shape compared to other onion varieties, typically weighing 8-12 ounces at maturity. When cut, the bulbs reveal crisp, white flesh with a moderately pungent flavor and excellent storage characteristics that distinguish this cultivar from shorter-storage varieties.

Appearance

Size & Dimensions

Height1'6" - 2'
Width/Spread4" - 6"

Colors

Flower Colors

white

Foliage Colors

blue
green

Fall Foliage Colors

yellow

Bloom Information

Bloom Period

J
F
M
A
M
J
J
A
S
O
N
D
Summer
midsummer to late summer

Detailed Descriptions

Flower Description

white

Foliage Description

blue-green

Growing Conditions

Sun Requirements

Full Sun
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.0(Neutral)
357912
Soil Types
loam
Drainage
well drained

Water & Climate

Water Needs

moderate

Frost Tolerance

hardy

Time to Maturity

110-120 days

Care & Maintenance

Care Guide

Allium cepa 'Superstar' requires full sun exposure and well-draining, fertile soil with a pH between 6.0-7.0 for optimal bulb development. Plant in early spring when soil temperatures reach 50-60°F, using sets, transplants, or direct-sown seed. Maintain consistent soil moisture during active growth but reduce watering as harvest approaches to promote proper curing. Apply a balanced fertilizer at planting, then side-dress with nitrogen when plants reach 6 inches tall and again when bulbs begin to swell. Hill soil around developing bulbs to encourage larger size and prevent green shoulders from sun exposure.

Pruning

Allium cepa 'Superstar' requires minimal pruning during the growing season, with the primary focus on removing flower stalks that may emerge to redirect energy into bulb development rather than seed production. Avoid cutting back the foliage until it naturally begins to yellow and fall over, which indicates the bulb has reached full maturity. After harvest, trim roots to 1/4 inch and cut stems to 1 inch above the bulb neck, then cure in a warm, dry, well-ventilated area at 80-85°F for 2-3 weeks before long-term storage.

Maintenance Level

low

Container Growing

✓ Suitable for container growing

⚠️ Toxicity Warning

Allium cepa 'Superstar' is safe for human consumption when properly prepared and cooked, though raw onions may cause digestive upset in sensitive individuals. All parts of the plant are toxic to dogs, cats, horses, and other pets, potentially causing hemolytic anemia, weakness, and gastrointestinal distress. Keep pets away from growing plants, harvested bulbs, and kitchen scraps containing onion material, as even small amounts can be dangerous.

Planting Guide

Planting Methods & Timing

Planting Method

both

Indoor Start

10 weeks before last frost

Direct Sow Timing

early spring, 2-3 weeks before last frost

Days to Maturity

110–120 days

Plant Spacing

4 inches

Companion Planting

Good Companions

tomatoes
carrots
brassicas
lettuce
peppers

Avoid Planting With

beans
peas
asparagus
sage