What are the sun requirements for Allium cepa 'Cabernet'?

Allium cepa 'Cabernet' is a red storage onion cultivar in the amaryllis family (Amaryllidaceae) reaching 12-18 inches (30-45 cm) tall with a 4-6 inch (10-15 cm) spread and an upright habit. The cultivar produces globe-shaped bulbs slightly flattened in profile, 3-4 inches (7-10 cm) in diameter, with deep burgundy-purple papery outer skins and rich wine-red internal flesh — the dark red coloration is the source of the wine-inspired name. Flesh shows red-purple rings concentric to the bulb axis, with a mild to moderately pungent flavor that sweetens when cooked. Foliage is hollow and tubular, blue-green, and reaches 12-18 inches in height. Cabernet is a long-day onion (14-16 hours daylight required for bulbing). Days to maturity 100-120 from sowing. The cultivar stores reasonably well — the dense flesh and pigmented skin support a 4-6 month holding window in proper conditions, less than dedicated long-storage cultivars like 'Australian Brown' but longer than fresh-eating types like 'Ailsa Craig'.

Native Range

Allium cepa is native to Central Asia (Iran, Afghanistan, Pakistan), where the species was domesticated over 4,000 years ago. The 'Cabernet' cultivar is a modern selection developed for deep red coloration through commercial onion breeding programs.

Suggested Uses

Grown in vegetable gardens for fresh culinary use, cooking, and storage. The deep red coloration suits raw applications in salads, sandwiches, and garnishes where color matters. The 4-6 month storage life makes the cultivar suited to home gardens producing a portion of the year's onion supply. Long-day type, so the cultivar is suited to latitudes above 36°N. Mild-to-moderate pungency, with sweetening on cooking, suits both raw and cooked preparations.

How to Identify

Identified by deep burgundy-purple outer skins and rich wine-red flesh with concentric red-purple rings visible in cross-section. Globe-shaped bulbs slightly flattened in profile, 3-4 inches (7-10 cm) across at maturity. Foliage is hollow tubular and blue-green with the strong onion aroma standard across Allium. Separated from other red onion cultivars by the particularly dark red skin coloration and the rich wine-red interior. Long-day type, in contrast to short-day red onions developed for southern latitudes.

Appearance

Size & Dimensions

Height1' - 1'6"

Width/Spread4" - 6"

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

Summer

Onions bolt to seed if exposed to prolonged cold during early growth, producing a single flower stalk topped with a white spherical umbel. Bolting reduces bulb size and quality. The cultivar is grown as an annual for bulb production, and any flower stalks appearing during the bulb season are cut at the base.

Detailed Descriptions

Flower Description

White in spherical umbels — only when the plant bolts, which is undesirable in a bulb crop

Foliage Description

Blue-green hollow tubular leaves

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

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

100-120 days

Care & Maintenance

Care Guide

Full sun in well-drained fertile soil at pH 6.0-7.0, with consistent moisture during the growing season. Compost amendment at planting and a balanced fertilizer side-dress when plants are 6 inches tall and again as bulbs swell support steady bulb development. Watering is reduced as harvest approaches to encourage proper curing. Long-day onion: bulbs form when daylight reaches 14-16 hours, suiting the cultivar to latitudes above 36°N. Fertilization stops 4-6 weeks before harvest. The dense pigmented flesh stores 4-6 months under proper curing and dry storage at 32-40°F (0-4°C). All Allium species contain thiosulfates that are toxic to dogs, cats, and horses; the bulb and foliage are not given to pets.

Pruning

Flower stalks appearing during the bulb season are cut at the base to direct energy into bulb development. Watering stops as harvest approaches and foliage is allowed to yellow and die back naturally. Green foliage is not cut during growth, since cutting reduces bulb size and storage life.