How to grow winter onions: from variety selection to winter care

Planting onions before winter guarantees an early spring harvest. For successful growing, it’s crucial to select proper varieties of winter onions, prepare soil and planting material, and provide necessary care. This comprehensive guide will help you understand how to achieve the best results when planting onions in winter.

Selecting winter onions sets

The success of planting onions in November starts with choosing the right varieties. When selecting varieties of winter onions, focus on cold-hardy types that have proven survivability onion characteristics in your growing zone. The key selection criteria include disease resistance, frost tolerance, and maturation period.

TOP 5 winter onions varieties

TOP-5 winter onions varieties for cold climate success

Variety Cold Hardiness Maturation Taste Additional Features
Stuttgarter Riesen High Early (June) Sharp High yield, disease resistant, excellent storage capability
Senshyu Yellow Medium Mid-season (Late June) Semi-sharp Crack resistant, perfect for southern states, good market value
Radar High Early (June) Sweet Stores up to 6 months, disease resistant, ideal for northern zones
Shakespeare High Early (June) Moderately sharp High pest resistance, compact growth, perfect for container growing
Wolf F1 High Mid-season (Late June) Sweet-mild Premium market quality, uniform bulbs, long storage life

*Note: maturation times are approximate and may vary depending on your specific USDA growing zone and local climate conditions.

Learn more: TOP-5 best varieties of winter garlic for planting in November

Understanding when and after what to plant winter onions

Many gardeners ask “Will onions grow in winter?” The answer depends on proper timing and crop rotation. The best crops to plant after include:

Root vegetables like carrots help break up the soil, making it ideal for winter onions sets. Legumes naturally enrich the soil with nitrogen, creating perfect conditions for planting onions before winter. Tomatoes and cucumbers leave behind well-structured soil that’s rich in nutrients, ideal for when you grow onions in fall.

Preparing onions for planting for the winter

Successful winter onion cultivation requires careful preparation of both planting material and soil. Choose strong, healthy, small bulbs (0.4-0.8 inches in diameter) with no signs of damage or disease. For optimal results, treat winter onions with a fungicide solution before planting. This preparation significantly increases the chances of success when planting onions in winter.

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Planting techniques and timing

Understanding when to plant winter onions is crucial for success. The perfect timing varies by climate zone, but generally falls between mid-October and late November. The key is allowing enough time for root development before hard freezes arrive.

Onion planting depth guidelines

Proper onion planting depth is essential for winter survival. Plant bulbs 1.5-2.5 inches deep in well-draining soil. This depth protects roots from freezing while allowing proper emergence. Space rows 6-8 inches apart to ensure adequate nutrition and airflow for your winter onions, bulb spacing: 2-4 inches.

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Winter protection and spring care

Winter protection

How to properly prepare onions for the winter involves several key steps. Mulch your beds with straw or leaves after the ground freezes to maintain consistent soil temperature. This protection is crucial for winter onions survival during harsh weather.

Spring maintenance

Understanding how to fertilize winter onions in spring is crucial for a successful harvest. Begin with a nitrogen-rich fertilizer when growth resumes in early spring. As bulbs develop, transition to a balanced fertilizer. This feeding schedule supports strong growth while maintaining plant health.

Growing in different conditions winter onion

Greenhouse growing winter onion

Growing winter onions in a greenhouse offers several advantages. The controlled environment allows for earlier planting and harvest times. Maintain temperatures between 59-68°F for optimal growth. Provide supplemental lighting during shorter winter days to ensure steady growth. Regular ventilation prevents disease issues common in enclosed spaces.

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Container growing winter onion

Winter onions can thrive in containers with proper care. Choose containers at least 12 inches deep with good drainage. Use premium potting soil mixed with compost for optimal nutrition. Place containers in a location that receives at least 6 hours of sunlight daily. Water consistently but avoid oversaturation.

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Harvesting and storing winter onions

Winter onions mature earlier than spring-planted varieties, typically from late June through early July depending on your USDA growing zone. The key indicator that your onions are ready for harvest is when the tops begin to yellow and fall over naturally. 

Harvesting process

Choose a clear day when the soil is relatively dry. Carefully loosen the soil around the bulbs with a garden fork, being careful not to damage them. Gently pull the onions from the ground by their tops. If the tops have already fallen over and dried, you may need to dig the bulbs out with a trowel.

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Curing your harvest winter onions

After harvesting, proper curing is essential for long-term storage success. Spread your onions in a single layer in a well-ventilated, shaded area such as:

  • A covered porch
  • A garage with good airflow
  • Under a canopy or awning
  • A dry basement with fans

Allow them to cure for 2-3 weeks, or until the necks are completely dry and the outer skins are papery. During this time, any remaining green tops will continue to dry and the outer layers will tighten around the bulb.

Storage conditions winter onions

Once properly cured, store your onions in a location that maintains optimal conditions:

  1. Temperature: 32-35°F
  2. Humidity: 60-70%
  3. Good ventilation

Ideal storage locations include:

  • Root cellars
  • Cool basements
  • Attached garages (in moderate climates)
  • Refrigerator crisper drawers
storage conditions winter onions

When stored properly under these conditions, most winter onions varieties can last 4-6 months or even longer. By following these comprehensive guidelines for planting onions in winter, you can ensure a successful early spring harvest. Remember that success depends on choosing the right varieties of winter onions, proper timing, and consistent care throughout the growing season. Whether you’re an experienced gardener or just starting out, growing winter onions can be a rewarding addition to your gardening calendar.

Video from the YouTube channel: “Growfully with Jenna”

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