Allium cepa 'Copra', Copra Onion
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At a Glance

TypeAnnual
HabitUpright
FoliageDeciduous
Height18-24 inches (45-60 cm)
Width4-6 inches (10-15 cm)
Maturity1 years

Overview

Allium cepa 'Copra' is Copra onion (Copra yellow storage onion), a biennial grown as an annual for bulb production, 18-24 inches (45-60 cm) tall and 4-6 inches (10-15 cm) wide. Globe-shaped bulbs 3-4 inches (7-10 cm) diameter, 8-12 ounces (225-340 g), with golden-bronze papery skins and pungent white flesh. A long-day storage onion: requires 14-16 hours of daylight for bulbing (latitudes above 36°N). F1 hybrid — seed does not produce true to type. Stores 8-10 months at 32-40°F (0-4°C) — one of the longest-storing yellow onions. The well-defined thin neck dries completely during curing — the key to long storage. Blue-green hollow tubular foliage. In the amaryllis family (Amaryllidaceae). Pungent raw, mellows when cooked. Start seed indoors 10-12 weeks before last frost. Harvest when 50-75% of tops have fallen and yellowed (100-110 days from transplant). Cure 2-4 weeks. Not a sweet onion — the pungent flavor is a limitation for raw eating. All Allium contain thiosulfates: toxic to dogs, cats, and horses. Onion maggot (Delia antiqua) and thrips are primary pests. Deer-resistant. Full sun. Annual. Growth rate is moderate.

Native Range

F1 hybrid cultivar. The species A. cepa is native to Central Asia (Iran, Afghanistan, Pakistan).

Suggested Uses

Grown in vegetable gardens and containers of at least 3 gallons (11 L). Long-storing yellow onion (8-10 months). Long-day type. Pungent — cooking onion. F1 hybrid. Toxic to pets. Deer-resistant. Annual.

How to Identify

Identified by globe-shaped bulbs with golden-bronze papery skins and pungent white flesh on a plant with blue-green hollow tubular foliage. The thin well-defined neck and the 8-10 month storage life distinguish Copra. Long-day storage type. F1 hybrid. In Amaryllidaceae.

Appearance

Size & Dimensions

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

Reaches mature size in approximately 1 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Biennial: flowers in the second year if overwintered — white spherical umbels. Grown as an annual for bulb production. Cut flower scapes at the base if they appear.

Detailed Descriptions

Flower Description

White spherical umbels — only if allowed to bolt; undesirable

Foliage Description

Blue-green, hollow tubular, 0.5-0.75 inch (12-18 mm) diameter; yellows at maturity

Growing Conditions

Sun Requirements

Requires 6-12 hours of direct sunlight daily
• 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
Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

100-110 days from transplant

Care & Maintenance

Care Guide

Full sun (6+ hours). Well-drained soil pH 6.0-7.0. Long-day onion — 14-16 hours daylight. Start seed 10-12 weeks indoors. Consistent moisture during bulb swelling. Reduce watering as tops yellow. Stores 8-10 months. F1 hybrid. All Allium toxic to pets. Deer-resistant. Annual.

Pruning

Cut flower scapes at the base if they appear. Do not cut green foliage during growth. Harvest when 50-75% of tops have fallen. Trim tops to 1 inch (2.5 cm), roots to 0.25 inch (6 mm). Cure 2-4 weeks.

Maintenance Level

low

Container Growing

✓ Suitable for container growing

Minimum container size: 3 gallons

⚠️ Toxicity Warning

Toxic to pets

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

100–110 days

Plant Spacing

4 inches

Companion Planting