Allium cepa 'Yellow Sweet Spanish'
vegetableA large, mild, all-purpose yellow storage onion — the backbone of most savory cooking worldwide. Milder than white onions when raw, it becomes rich and sweet when cooked. A sweet, long-day onion that, well cured, keeps a moderate 2 to 4 months - sweet Spanish types are mild and are not long-storage onions. Spanish onions refer to the largest, mildest yellow types.
Sun
full sun
Water
Every 3 days
Harvest
~110 days
Difficulty
easy
Lifecycle
biennial
Leaves year 1, flowers year 2
Spacing
4-6 in
Planting Depth
1/2-1 in (sets or transplants)
Soil pH
6.0-7.0
Soil Type
Loose, well-draining
Hardiness Zones
Zones 3 – 10
Grown as an annual — this range is its winter hardiness, but you can grow it for a single season in any zone.
When to Fertilize
Nitrogen-rich fertilizer at planting and when tops reach 6 to 8 inches; stop feeding once bulbs begin to swell
Fertilizer
High-nitrogen fertilizer early; balanced formula as bulbs form
Start from transplants or sets for best results. Onions need the right day-length for bulbing — match long-day varieties to northern gardens and short-day to southern; Yellow Sweet Spanish is a long-day type best grown in the North. Plant 4 to 6 weeks before last frost date. Consistent weed control is critical — onions compete poorly with weeds. When tops fall over naturally, stop watering and allow bulbs to begin curing in the ground.
Start seeds indoors
Feb 4
Transplant outdoors
Mar 18
Projected first harvest
Jul 6
Good neighbors that attract beneficial insects or deter pests
Proactive ways to stop trouble before it starts — tap a name with an arrow for its full guide
Row cover from planting; avoid fresh manure; crop rotation annually
Reflective silver mulch; spinosad spray if severe
Cure thoroughly after harvest; store only fully dry bulbs
8-year rotation if detected; never replant alliums in infected soil
Harvest when about half the tops have naturally fallen over; waiting much longer shortens storage life. Gently loosen bulbs with a fork and pull carefully. Cure in a warm (75 to 85 F), dry, well-ventilated location for 3 to 4 weeks. Skin should be fully papery and the neck completely dry before storage. Store in mesh bags in a cold (near 32 F), dry, dark place - onions sprout above 40 F - and expect about 2 to 4 months for this sweet type.
Good source of vitamin C, B6, folate, and quercetin antioxidant. Sulfur compounds have documented antimicrobial and cardiovascular-protective properties. As a sweet onion it is relatively low in sulfur, which makes it mild and sweet but also a shorter keeper than pungent storage onions.
For educational and informational purposes only — HomeSown is not medical, health, or other professional advice. Always positively identify any plant before handling or eating it; some plants, and some parts of otherwise-edible plants, are toxic. Consult a qualified professional before consuming or otherwise using any plant, especially if you are pregnant, nursing, taking medication, or have a health condition.