Yellow Sweet Spanish Onion
Allium cepa 'Yellow Sweet Spanish'
A classic long-day onion variety beloved for producing enormous, mild-flavored bulbs that can reach softball size or larger. These golden-skinned beauties are incredibly versatile in the kitchen, sweet enough to eat raw yet substantial enough for cooking. Perfect for northern gardeners who want to grow impressive onions that store well through winter.
Harvest
110-120d
Days to harvest
Sun
Full sun
Zones
5–10
USDA hardiness
Height
12-18 inches
Planting Timeline
Showing dates for Yellow Sweet Spanish Onion in USDA Zone 7
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Yellow Sweet Spanish Onion · Zones 5–10
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | — | — | May – June | August – October |
| Zone 4 | — | — | April – June | August – October |
| Zone 5 | — | — | April – May | August – November |
| Zone 6 | — | — | April – May | July – November |
| Zone 7 | — | — | March – May | July – November |
| Zone 8 | — | — | March – April | June – December |
| Zone 9 | — | — | February – March | May – December |
| Zone 10 | — | — | January – March | May – December |
Complete Growing Guide
Light: Full sun (6 or more hours of direct sunlight a day). Soil: High Organic Matter, Loam (Silt), Sand. Soil pH: Alkaline (>8.0), Neutral (6.0-8.0). Drainage: Good Drainage, Moist. Height: 1 ft. 0 in. - 1 ft. 6 in.. Spread: 0 ft. 6 in. - 1 ft. 0 in.. Spacing: Less than 12 inches, 12 inches-3 feet. Maintenance: Medium. Regions: Coastal, Mountains, Piedmont.
Harvesting
Flowers wither and convert to bulblets
Type: Capsule.
Harvest time: Summer
Bloom time: Summer
Storage & Preservation
Cure harvested onions in a warm (80-85°F), well-ventilated area for 2-3 weeks until outer skins rustle and necks are completely dry and tight. Properly cured Yellow Sweet Spanish onions store 6-8 months in cool (32-40°F), dry conditions with good air circulation.
Store only perfect bulbs with tight necks in mesh bags, braided strings, or shallow boxes—never in plastic bags which trap moisture. Check monthly and remove any showing soft spots immediately to prevent spread.
For preservation, these mild onions excel when sliced and frozen in freezer bags (no blanching required), maintaining flavor for 8-10 months. They're also excellent for dehydrating into onion powder or flakes using a food dehydrator at 115°F for 12-18 hours. Their sweet nature makes them perfect for making pickled onions or onion jam for long-term storage.
History & Origin
Yellow Sweet Spanish onions trace their lineage to varieties originally developed in Valencia, Spain, where the Mediterranean climate and fertile soils produced exceptionally large, mild bulbs prized throughout Europe. Spanish colonizers brought these genetics to the Americas in the 16th century, where they adapted to various growing regions.
The modern Yellow Sweet Spanish was refined through selective breeding in the early 1900s by American seed companies who recognized the potential for large, storage-type onions in northern climates. The variety became particularly popular during the World War II victory garden era when home gardeners needed reliable, long-storing vegetables.
This heirloom variety helped establish the reputation of regions like Walla Walla, Washington and Vidalia, Georgia as premier onion-growing areas, though the Spanish genetics performed best in northern latitudes where long summer days could trigger proper bulbing. The variety's ability to produce enormous bulbs while maintaining sweetness made it a staple in American gardens throughout the mid-20th century.
Advantages
- +Disease resistance: Black Walnut, Deer, Rabbits
Considerations
- -Toxic: Low severity
Companion Plants
Plant Together
Carrots
Onions repel carrot fly while carrots help break up soil for onion bulb development
Tomatoes
Onions deter aphids, whiteflies, and hornworms that commonly attack tomatoes
Cabbage
Onions repel cabbage worms, cabbage loopers, and flea beetles
Lettuce
Onions provide pest protection while lettuce doesn't compete for space with shallow roots
Peppers
Onions deter aphids and spider mites that target pepper plants
Broccoli
Onions repel cabbage family pests including cabbage maggots and aphids
Spinach
Onions protect spinach from leaf miners and aphids while maximizing garden space
Strawberries
Onions deter slugs, aphids, and nematodes that damage strawberry plants
Keep Apart
Beans
Onions inhibit nitrogen fixation in bean roots and can stunt bean growth
Peas
Onions interfere with nitrogen fixation and root nodule development in pea plants
Asparagus
Both compete for similar soil nutrients and onions can inhibit asparagus spear development
Nutrition Facts
Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #170000)
Pests & Disease Resistance
Resistance
Good resistance to pink root and fusarium basal rot
Common Pests
Onion thrips, onion maggot, cutworms
Diseases
Downy mildew, purple blotch, white rot