What hardiness zones is Allium cepa 'Copra' suitable for?

Allium cepa 'Copra' is suitable for USDA hardiness zones 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b.

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

Allium cepa 'Copra' requires full sun.

How much water does Allium cepa 'Copra' need?

Allium cepa 'Copra' has moderate water needs.

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Annuals

Allium cepa 'Copra'

Copra 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

Container Friendly

Maintenancelow

Overview

Allium cepa 'Copra' is a highly productive, long-day storage onion cultivar renowned for its exceptional keeping quality and uniform bulb development. This annual vegetable produces large, globe-shaped bulbs with distinctive golden-bronze outer skin and crisp, pungent white flesh beneath multiple layers of papery scales. The robust bulbs typically weigh 8-12 ounces at maturity and develop a well-defined neck that dries down completely, contributing to their superior 8-10 month storage life. The foliage consists of hollow, cylindrical blue-green leaves that emerge directly from the bulb base in a characteristic fan-like arrangement, reaching 18-24 inches in height. The leaves are distinctively hollow when squeezed, producing a characteristic popping sound that distinguishes them from solid-leaved allium species. Allium cepa 'Copra' is distinguished from other onion cultivars by its consistent bulb shape, excellent neck drying characteristics, and remarkable post-harvest longevity, making it a preferred choice for commercial growers and home gardeners seeking reliable storage onions.

Native Range

Allium cepa is native to the mountainous regions of Central Asia, specifically the highland areas of Afghanistan, Iran, Tajikistan, and surrounding territories. The species has been cultivated for over 5,000 years and has spread worldwide through human cultivation and trade, though wild populations still exist in rocky slopes and alpine meadows of its native range.

Suggested Uses

vegetable garden, raised beds, container growing, long-term food storage, crop rotation systems

How to Identify

Allium cepa 'Copra' can be identified by its characteristic hollow, tubular blue-green foliage that produces a distinctive popping sound when squeezed, distinguishing it from solid-leaved alliums. The developing bulbs display the cultivar's signature golden-bronze papery outer scales and globe shape, becoming increasingly prominent as the season progresses. As maturity approaches, the neck area softens and the tops begin to fall over naturally, indicating readiness for harvest. The shallow, fibrous white root system and strong onion aroma when disturbed are additional identifying characteristics typical of this storage onion cultivar.

Appearance

Size & Dimensions

Height1'6" - 2'

Width/Spread4" - 6"

Colors

Flower Colors

white

Foliage Colors

blue

green

Fall Foliage Colors

brown

Bloom Information

Bloom Period

Summer

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

Drainage

well drained

Water & Climate

Water Needs

moderate

Frost Tolerance

hardy

Time to Maturity

100-110 days

Care & Maintenance

Care Guide

Allium cepa 'Copra' requires consistent moisture throughout the growing season, particularly during active bulb development in mid to late summer. Water deeply but infrequently, maintaining even soil moisture while avoiding waterlogged conditions that can promote bulb rot. Apply a balanced fertilizer at planting time and side-dress with nitrogen-rich fertilizer when plants reach 6 inches in height to support vigorous foliage growth. Reduce watering frequency as the tops begin to yellow and fall over naturally, allowing the bulbs to cure properly. Maintain weed-free growing conditions as onions compete poorly with weeds due to their shallow root system and sparse foliage.

Pruning

Allium cepa 'Copra' requires minimal pruning during the growing season, with the primary focus on removing flower stalks if they appear to redirect energy into bulb development rather than seed production. Avoid cutting or trimming the green foliage as these leaves are essential for photosynthesis and bulb sizing. Once the tops naturally begin to fall over and turn yellow-brown, cease watering and allow them to cure in the ground for 7-10 days before harvesting. After harvest, trim the dried tops to 1-2 inches above the bulb neck for optimal storage preparation.

Maintenance Level

low

Container Growing

✓ Suitable for container growing

⚠️ Toxicity Warning

Allium cepa 'Copra' is safe for human consumption both raw and cooked, providing culinary and nutritional benefits. However, all parts of the plant, including bulbs and foliage, contain organosulfur compounds that are toxic to dogs, cats, horses, and other pets, potentially causing hemolytic anemia and gastrointestinal distress. Keep harvested bulbs and plant debris away from animals, and seek veterinary attention if pet ingestion is suspected.

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

Good Companions

carrots

tomatoes

peppers

brassicas

lettuce

Avoid Planting With

beans

peas

asparagus