Onion

Basic Information

Seed Number

219

Seed Name

Onion

Variety

Sweet Spanish

Category

Vegetable

Plant Family

Amaryllidaceae

Plant Type

Long-day sweet bulbing onion (Allium cepa)

Planting Method

Direct Sow or Transplant

Seed Status

In Seed Bank

Created

2026-08-14 00:50:34

Updated

2026-08-19 15:35:29

Planting Information

Start Planting Date

Feb 10

Last Recommended Planting Date

May 15

Plantable Months

February, March, April, May

Indoor Start

Feb 10 – Feb 24

Direct Sow

Mar 15 – Apr 15

Transplant

Apr 15 – May 15

Indoor Start Weeks Before Frost

12 weeks

Transplant Weeks After Frost

Not recorded

Germination Days

5–10 days

Harvest/Maturity

107–115 days

Succession Planting

Not recorded

Growing Conditions

Ideal Soil Temperature

60-75°F

Planting Depth

1/4 in

Plant Spacing

3-6 in

Row Spacing

12-18 in

Thin-To Spacing

3-6 in

Sun Requirements

Full sun

Water Needs

About 1 in/week during active bulb growth

Soil Preference

Fertile, well-drained soil amended with compost

Minimum Container Size

8–10+ in deep

Plant Height

Not recorded

Perennial/Biennial Status

Biennial

Container Friendly

Yes

Trellis/Support Needed

No

Frost Tolerant

Yes

Heat Tolerant

No

Drought Tolerant

No

Pollinator Friendly

Yes

Medicinal

No

Garden Uses

Companion Planting

Storage

Seed Source/Brand

Ferry-Morse; MSU Extension

Packet Year

Not recorded

Quantity Notes

Not recorded

Purchase Date

Not recorded

Expiration Year

Not recorded

Storage Box

Not recorded

Container

Not recorded

Envelope

Not recorded

Row

Not recorded

Slot

Not recorded

Storage Notes

Not recorded

Notes

Original Planting Method: Start indoors 8–12 weeks before last frost; transplant early or direct sow as soon as soil can be worked
Outdoor / Direct Sow / Transplant Window: Transplant/direct sow about Mar 25 – Apr 30
Germination Time: About 10–12 days
Days to Harvest / Bloom: About 115–120 days
Container Friendly: Yes, 8–10+ in deep
Pollinator Friendly: Low if harvested; second-year flowers attract pollinators
Medicinal / Herbal Use: Culinary onion
Perennial?: Biennial botanically; usually grown as an annual bulb crop
Succession / Reusable Notes: One early sowing is usually enough; cure mature bulbs after tops fall.
Zone 6B Notes: Long-day onions are appropriate for Michigan. Start early indoors for the largest bulbs.
Companion Plants: Carrots, beets, lettuce, cabbage-family crops and tomatoes
Avoid Planting Near / Watch Outs: Needs a long season and consistent weeding because young onions compete poorly. Avoid waterlogged soil.
Sources: Ferry-Morse: https://ferrymorse.com/products/onion-sweet-spanish-yellow-utah-jumbo | MSU Extension: https://www.canr.msu.edu/resources/garden_planning_calendar

[[RESEARCH ENRICHMENT START]]
Zone 6B: Sweet Spanish is generally represented by long-day northern strains such as Yellow Sweet Spanish or Utah Yellow Sweet Spanish, which are suitable for Southeast Michigan.
Germination: Start indoors 8-12 weeks before planting out for maximum bulb size.
Harvest: Harvest when tops fall naturally and necks soften. Cure in a warm, dry, ventilated location before storage.
Seed Saving: Allium cepa is biennial and crosses readily with other flowering onion cultivars.
Special Care: The packet does not specify yellow or white Sweet Spanish. Values are based on the common long-day Yellow Sweet Spanish type; exact bulb color is therefore not assigned.
Research Source: Pinetree Garden Seeds — https://www.superseeds.com/products/yellow-sweet-spanish-onion — 107-day Yellow Sweet Spanish maturity, 5-10 day germination, 60-75°F temperature, 1/4-inch depth, 8-10 week indoor start and long-day classification
Research Source: Urban Farmer — https://www.ufseeds.com/product/yellow-sweet-spanish-onion-seeds---1-pound/ONYSS-1-pound.html — Allium cepa identity, 110-day maturity, long-day classification, spacing and row spacing
[[RESEARCH ENRICHMENT END]]