Planting Guides

When to Plant Onions in Minneapolis: Complete Guide + Best Varieties for Zone 4a

Minneapolis, Minnesota

USDA Zone 4a

Last Frost: May 15

Last updated: December 8, 2025

Learn when to plant onions in Minneapolis with specific dates for Zone 4a. Compare 6 varieties & discover which onions grow best in Minnesota's climate.

DDorothy "Dot" Williams

December 8, 2025

Fresh harvested onions on wooden table with Minneapolis skyline background showing successful Zone 4a onion growing — — Image © PlantReference.org 2025

Quick Answer

Plant onions in Minneapolis April 15-30 with long-day varieties like Walla Walla. Harvest August-September after 110-125 growing days.

TL;DR

Plant onions in Minneapolis from April 15-30 using long-day varieties like Walla Walla or Red Wing. Minneapolis' Zone 4a requires varieties needing 14+ hours daylight to bulb properly. Plant garlic in mid-October for June harvest.

Product Recommendations

Johnny's Selected Seeds Red Wing Onion Sets

($12-18)— Premium storage onion perfect for Minnesota

Red Wing F1 Hybrid Storage Onion Sets - 60 Count

https://www.johnnyseeds.com/vegetables/onions/full-size-onions/redwing-f1-onion-seed-2137.html

Premium F1 hybrid red storage onion specifically bred for northern climates. Produces uniform globe-shaped bulbs with excellent storage potential (8-10 months when properly cured). Strong disease resistance including pink root tolerance. Requires long-day conditions (14+ hours) making it perfect for Minneapolis latitude. Deep red interior rings maintain color through storage. Sets are sized smaller than dime to prevent bolting.

Price: $12.99-$17.99

Territorial Seed Walla Walla Sweet Onion Plants

($14-22)— Best sweet onion for Minneapolis

Walla Walla Sweet Onion Transplants - Bundle of 75 Plants

https://territorialseed.com/products/walla-walla-sweet-onion-plants

Cold-hardy sweet onion transplants perfect for Minneapolis spring planting. These long-day onions produce jumbo-sized bulbs with exceptional sweetness and mild flavor. Can be fall-planted with protection for early summer harvest. Transplants are 6-8 weeks old, giving head start over sets. Excellent fresh eating quality but limited storage life (1-2 months). Ships at optimal planting time for your zone.

Price: $14.99-$21.99

High Mowing Seeds Music Garlic Bulbs

($16-24)— Premium hardneck garlic for cold climates

Music Hardneck Garlic Bulbs - Certified Organic - 1/2 Pound

https://www.highmowingseeds.com/organic-garlic-music.html

Certified organic Music garlic bulbs ideal for Minneapolis Zone 4a conditions. This porcelain hardneck variety thrives in cold climates, producing large bulbs with 4-6 jumbo cloves. Rich, complex flavor when raw, sweet when roasted. Excellent cold hardiness and disease resistance. Produces edible scapes in late spring. Plant in October for June harvest. Good storage life (6-8 months) for hardneck type.

Price: $16.99-$23.99

Peaceful Valley Organic Soil Thermometer

($18-25)— Essential for proper planting timing

Digital Soil Thermometer with 12-inch Probe

https://www.groworganic.com/products/soil-thermometer-digital-12-inch-probe

Professional-grade digital thermometer with 12-inch stainless steel probe for accurate soil temperature readings. Essential for timing Minneapolis onion plantings when soil reaches consistent 35°F. Large LCD display shows both Fahrenheit and Celsius. Waterproof design withstands Minnesota spring conditions. Memory function records high/low temperatures. Includes protective case and battery. Accurate to ±1°F for precise planting decisions.

Price: $18.99-$24.99

Gardener's Supply Onion Storage Bags

($12-18)— Proper storage for winter keeping

Mesh Onion Storage Bags - Set of 6

https://www.gardeners.com/buy/onion-storage-bags/8593844.html

Breathable mesh storage bags designed specifically for long-term onion storage through Minnesota winters. Heavy-duty nylon mesh allows proper air circulation while protecting from light. Each bag holds 10-15 pounds of cured onions. Drawstring closure prevents spillage. Easy to hang in basement or root cellar. Extends storage life by preventing moisture buildup and sprouting. Essential for preserving Minneapolis onion harvest through spring.

Price: $12.99-$17.99

Frequently Asked Questions

What's the latest I can plant onions in Minneapolis?

April 30 is your absolute deadline for spring onion planting in Minneapolis. Later planting doesn't give enough time for adequate leaf development before our summer solstice triggers bulbing. I've seen people try May plantings, but they always get small bulbs that barely store through winter. The onions need those cool spring weeks to build the foliage that becomes your storage bulbs.

Can I grow short-day onions like Texas varieties in Minneapolis?

No, don't waste your time. Short-day onions need only 10-12 hours of daylight to trigger bulbing, but Minneapolis gets 15+ hours in summer. They'll stay in leaf production mode all season and never form bulbs. You might get massive green tops, but no storage onions. Stick with long-day varieties—it's the only type that works at our 45°N latitude.

Should I use onion sets, transplants, or seeds in Minneapolis?

Sets are your best bet for Minneapolis. Our growing season is only 138 days, which doesn't give enough time to start from seed unless you're growing them indoors for 8-10 weeks. Transplants work well too, but sets are more cold-tolerant and handle our unpredictable April weather better. Choose sets smaller than a dime—large ones bolt when hit by late frost followed by warm spells.

When should I plant garlic in Minneapolis, and what type works best?

Plant garlic October 10-15 in Minneapolis, about 4-6 weeks before ground freezes. Use hardneck varieties like Allium sativum 'Music' or Allium sativum 'German Extra Hardy'—they need our cold winters for proper clove development. Softneck types don't get enough chill hours here and often produce solid bulbs instead of separated cloves.

My onions formed flower stalks in June. What went wrong?

That's bolting, usually caused by planting large onion sets (bigger than a dime) or temperature stress from late cold snaps. Large sets are biologically older and think they've been through a winter when hit by cold followed by warm weather. Cut those flower stalks immediately to salvage some bulb development, but expect smaller onions that won't store well. Next year, use smaller sets and wait until soil consistently stays above 35°F.

How do I store Minneapolis-grown onions through winter?

Cure them properly first—that's the key. After harvest, dry bulbs in single layers in a warm (75-80°F (24-27°C)), dry, ventilated area for 2-4 weeks until skins are papery. Then store at 32-40°F (0-4°C) with 60-70% humidity. Most Minneapolis basements work perfectly. Don't store with potatoes, and check monthly, removing any that show soft spots. Well-cured storage varieties like Allium cepa 'Red Wing' keep until March.

Can I plant onions in fall for overwintering in Minneapolis Zone 4a?

It's risky in Minneapolis. While some gardeners succeed with heavy mulch protection, our Zone 4a winters often kill overwintering onions. The specialty overwintering varieties like Allium cepa 'Bridger' are bred for Zones 6-7 with milder winters. Stick with spring planting for reliable results, though you can try a small test patch with 6 inches (15 cm) of straw mulch if you want to experiment.

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Written By

Dorothy "Dot" Williams

Dot grew up on a small farm in rural Virginia and has maintained a vegetable garden for decades. After retiring from teaching elementary school, she became a Master Gardener volunteer and spends her time mentoring new gardeners at community garden plots in Richmond. She's especially knowledgeable about heirloom varieties, seed saving, and traditional growing methods passed down from her grandmother. Dot's no-nonsense advice comes from extensive trial and error—she's seen every tomato disease, pest problem, and weather disaster imaginable. Her biggest pet peeve is gardeners who overcomplicate simple tasks. "Plants want to grow," she often says. "Your job is to not get in their way."