Allium cepa 'Yellow Sweet Spanish', Yellow Sweet Spanish Onion
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Annuals

Allium cepa 'Yellow Sweet Spanish'

Yellow Sweet Spanish Onion

AmaryllidaceaeAsia

At a Glance

Typeannual
Habitupright
Foliagedeciduous
Height18-24 inches
Width6-8 inches
Maturity1 years

Growing Zones

USDA Hardiness Zones

4a - 9b
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 'Yellow Sweet Spanish' is a large, impressive onion cultivar renowned for producing exceptionally sized bulbs with remarkably mild, sweet flavor. This vigorous biennial plant, cultivated as an annual crop, develops massive flattened globe-shaped bulbs that can reach 4-5 inches in diameter and weigh over a pound at maturity. The bulbs feature distinctive golden-brown papery outer skins that protect multiple layers of crisp, white to pale yellow flesh with a notably sweet, delicate taste that lacks the sharp bite of storage onion varieties. The plant produces characteristic hollow, cylindrical blue-green leaves that emerge directly from the bulb base in an attractive fountain-like arrangement, typically reaching 18-24 inches in height. These tubular leaves are distinctly different from flat-leaved plants, with their hollow structure being a key identifying feature of the Allium genus. Allium cepa 'Yellow Sweet Spanish' is distinguished from other onion cultivars by its exceptional bulb size, relatively thin neck where the leaves emerge, and outstanding fresh eating qualities that make it ideal for applications requiring mild onion flavor.

Native Range

Allium cepa originated in the mountainous regions of Central Asia, particularly in the highlands of modern-day Afghanistan, Iran, and the surrounding areas of the Iranian plateau. Wild ancestors of cultivated onions naturally occurred in these elevated regions and gradually spread throughout the Mediterranean basin and beyond through ancient trade routes and human migration. The 'Yellow Sweet Spanish' cultivar itself was developed through selective breeding programs, representing centuries of cultivation and improvement from these ancient wild ancestors.

Suggested Uses

Allium cepa 'Yellow Sweet Spanish' excels in dedicated vegetable gardens, raised beds, and large containers where its substantial mature size can be properly accommodated. The exceptionally mild, sweet flavor profile makes it perfect for fresh eating applications including raw preparations, salads, sandwiches, and garnishes where a subtle onion taste is desired without overwhelming heat. Outstanding for cooking applications that benefit from large, mild onions such as stuffed onions, grilling whole bulb halves, roasting, and caramelizing for soups and stews. Suitable for short-term storage when properly cured, and ideal for beginning gardeners due to its reliable growth habit, relatively pest-resistant nature, and forgiving cultivation requirements.

How to Identify

Allium cepa 'Yellow Sweet Spanish' can be easily identified by its extraordinarily large, flattened globe-shaped bulbs that are significantly bigger than most onion varieties, often reaching 4-5 inches across. The bulbs display characteristic golden-brown papery outer skins with multiple layers of white to pale yellow flesh that has a distinctly mild, sweet flavor when tasted. The plant's hollow, cylindrical blue-green leaves are tubular rather than flat, emerging from the bulb base in an upright fountain pattern and reaching 18-24 inches tall. The neck area where leaves attach to the bulb is relatively thin compared to the bulb's substantial girth, and if allowed to flower in the second year, tall flower stalks develop topped with spherical clusters of small white to greenish-white flowers.

Appearance

Size & Dimensions

Height1'6" - 2'
Width/Spread6" - 8"

Reaches mature size in approximately 1 years

Colors

Flower Colors

white
green

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
second year summer if allowed to overwinter

Detailed Descriptions

Flower Description

white to greenish-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

110-120 days

Care & Maintenance

Care Guide

Allium cepa 'Yellow Sweet Spanish' requires consistent soil moisture throughout the growing season, particularly during the crucial bulb development period from mid-season onward. Water regularly to maintain even moisture levels, providing approximately 1 inch of water per week, but ensure excellent drainage to prevent bulb rot and fungal diseases that can destroy the crop. Apply a balanced 10-10-10 fertilizer at planting time, then side-dress with nitrogen-rich fertilizer when plants reach 6 inches tall to promote robust foliage growth. Switch to a phosphorus and potassium-rich fertilizer during mid-season to encourage proper bulb formation and size development. Stop all fertilization 4-6 weeks before harvest to allow bulbs to mature properly. Maintain weed-free growing areas through regular cultivation or mulching, as onions compete poorly with weeds for nutrients and water due to their shallow root systems.

Pruning

Allium cepa 'Yellow Sweet Spanish' requires minimal pruning during active growth, with healthy green foliage being absolutely essential for proper bulb development and size. Avoid cutting or removing green tops unless they become damaged, diseased, or broken, as these leaves manufacture and transport food to the developing bulbs below ground. Remove any flower stalks (scapes) immediately if they begin to form, pinching or cutting them at the base to redirect the plant's energy into bulb growth rather than seed production. As harvest time approaches in late summer, monitor the foliage and stop watering when about half the tops begin to yellow and naturally fall over, then allow all remaining foliage to dry down completely before harvesting the mature bulbs.

Pruning Schedule

J
F
M
A
M
J
J
A
S
O
N
D
summerfall

Maintenance Level

low

Container Growing

✓ Suitable for container growing

Minimum container size: 5 gallons

⚠️ Toxicity Warning

Allium cepa 'Yellow Sweet Spanish' is completely safe and widely consumed by humans as a nutritious food crop with no known toxicity concerns. However, like all members of the Allium family, this onion variety is toxic to dogs, cats, horses, and other household pets and livestock. Ingestion can cause hemolytic anemia, gastrointestinal upset, weakness, difficulty breathing, and other serious health complications that may require emergency veterinary treatment. Both raw and cooked onions are dangerous to animals, so store harvested bulbs securely and protect growing plants from pet access to prevent accidental consumption.

Planting Guide

Planting Methods & Timing

Planting Method

transplant

Indoor Start

10 weeks before last frost

Direct Sow Timing

early spring, 4-6 weeks before last frost

Days to Maturity

110–120 days

Plant Spacing

4 inches

Companion Planting

Good Companions

tomatoes
peppers
cabbage
broccoli
carrots
lettuce

Avoid Planting With

beans
peas
asparagus
Allium cepa 'Yellow Sweet Spanish' (Yellow Sweet Spanish Onion) - Identification & Care Guide | PlantRef