Allium cepa 'Yellow Granex', Yellow Granex Onion
Annuals

Allium cepa 'Yellow Granex'

Yellow Granex Onion

UnknownAsia

At a Glance

Typeannual
Habitupright
Foliagedeciduous
Height12-18 inches
Width4-6 inches

Key Features

Deer Resistant
Fragrant (moderate)
Container Friendly
Maintenancelow

Overview

Allium cepa 'Yellow Granex' is a popular short-day onion cultivar known for producing large, mild-flavored yellow bulbs. This annual vegetable forms a distinctive bulbous base with papery golden-brown outer scales and crisp white to pale yellow interior layers. The plant produces hollow, blue-green cylindrical leaves that emerge from the bulb base and can reach 12-18 inches in height. The foliage has a characteristic onion scent when crushed and serves as an excellent indicator of bulb development below ground. Allium cepa 'Yellow Granex' is specifically bred for warm climates and requires shorter daylight periods to initiate bulbing, making it ideal for southern growing regions. The bulbs are typically globe-shaped when mature, with a relatively flat bottom and can reach 3-4 inches in diameter when properly grown.

Native Range

Allium cepa is believed to be native to southwestern Asia, particularly regions of modern-day Iran and Pakistan. The species has been cultivated for thousands of years and has spread worldwide through human cultivation, with 'Yellow Granex' being a modern cultivar developed specifically for warm-climate growing conditions.

Suggested Uses

Allium cepa 'Yellow Granex' works well in vegetable gardens, raised beds, and container growing. Excellent for fresh eating due to its mild flavor, and suitable for short-term storage. Ideal for southern gardens and warm climates where long-day onions struggle to bulb properly. Can be grown as green onions if harvested early or allowed to mature into full-sized storage onions.

How to Identify

Allium cepa 'Yellow Granex' can be identified by its hollow, cylindrical blue-green leaves that emerge from a developing underground bulb. The leaves are distinctly different from other alliums by being completely hollow rather than flat, and when crushed, emit the characteristic sharp onion aroma. As the plant matures, the bulb swells at the soil surface, developing papery golden-brown outer scales. The 'Yellow Granex' cultivar specifically produces globe-shaped bulbs with yellow storage scales rather than white or purple varieties.

Appearance

Size & Dimensions

Height1' - 1'6"
Width/Spread4" - 6"

Colors

Flower Colors

white

Foliage Colors

blue
green

Fall Foliage Colors

yellow

Bloom Information

second year if allowed to bolt

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
average

Water & Climate

Water Needs

moderate

Frost Tolerance

hardy

Time to Maturity

100-110 days

Care & Maintenance

Care Guide

Allium cepa 'Yellow Granex' requires consistent moisture during early growth but should be allowed to dry as bulbs mature. Water regularly during leaf development, providing about 1 inch per week, but reduce watering as foliage begins to yellow and fall over, indicating bulb maturity. Fertilize with a balanced fertilizer at planting and side-dress with nitrogen when plants are 6 inches tall. Stop fertilizing once bulbing begins to avoid delaying maturity. Ensure good air circulation and avoid overhead watering to prevent fungal diseases.

Pruning

Allium cepa 'Yellow Granex' requires minimal pruning during growth. Remove any flower stalks that appear to direct energy into bulb development rather than seed production. Do not cut back foliage until it naturally yellows and falls over, as the leaves are essential for bulb development. Once foliage has dried and fallen, cure bulbs by allowing them to dry in a warm, well-ventilated area for 2-3 weeks before storage.

Maintenance Level

low

Container Growing

✓ Suitable for container growing

Minimum container size: 5 gallons

⚠️ Toxicity Warning

Allium cepa 'Yellow Granex' is generally safe for human consumption when properly prepared, though raw onions can cause digestive upset in sensitive individuals. All parts of the onion plant are toxic to dogs, cats, and other pets, potentially causing anemia and gastrointestinal problems. Keep harvested onions and plant debris away from pets.

Planting Guide

Planting Methods & Timing

Planting Method

both

Indoor Start

10 weeks before last frost

Direct Sow Timing

early spring when soil can be worked

Days to Maturity

100–110 days

Plant Spacing

4 inches

Companion Planting

Good Companions

tomatoes
peppers
carrots
lettuce
cabbage
broccoli

Avoid Planting With

beans
peas
asparagus