The Ultimate Guide to Autumn Onion Varieties: Growing and Harvesting Overwintering Onions

Introduction

Onions are a staple in nearly every cuisine around the world, adding flavor and depth to a wide range of dishes. If you’re a gardening enthusiast looking to grow onions that can thrive in the cold months and provide an early harvest in the following year, autumn onions are an excellent choice. These hardy varieties are specially bred for planting in the cooler season, allowing them to establish roots before winter sets in and burst into growth come springtime. In this ultimate guide, we will dive into everything you need to know about growing autumn onion varieties, including the benefits, growing techniques, and detailed descriptions of popular varieties you can cultivate in your garden.

What Are Autumn Onions?

Autumn onions, also known as overwintering onions, are a special type of onion that is planted in the fall. Unlike spring-planted onions, these varieties are hardy and can withstand the cold winter months. When planted in the autumn, they have time to establish strong root systems before the weather gets too cold. They enter a dormant phase during the harshest winter months and resume growth as soon as temperatures rise in early spring, providing an early harvest of fresh, flavorful onions.

The major advantage of planting onions in autumn is that they allow you to make better use of your garden space and get a head start on the growing season. By the time spring arrives, you’ll already have a strong, established crop ready to grow vigorously as temperatures rise, ensuring an earlier harvest compared to spring-planted onions.

Benefits of Growing Autumn Onions

Early Harvest: One of the biggest benefits of autumn onions is that they are ready for harvest much earlier than onions planted in the spring. This means you’ll have fresh onions available before many other garden vegetables are ready.
Cold Hardy: Autumn onions are specially bred to withstand cold temperatures, making them ideal for growing in climates with harsh winters. They will survive the winter and resume growth in early spring.
Efficient Garden Use: Planting onions in autumn helps maximize your garden’s productivity. It allows you to utilize garden space during the colder months when many other crops cannot be grown.
Pest Resistance: By establishing themselves in cooler weather, autumn onions are less susceptible to pests that are more common during the warmer months. This means less need for pest control and fewer issues with infestations.

Popular Varieties of Autumn Onions

There are many different varieties of onions that can be planted in the autumn. Below, we cover some of the most popular and successful varieties for overwintering.

1. Senshyu Yellow

Senshyu Yellow is a traditional Japanese onion variety that has become popular among gardeners around the world for its cold tolerance and reliability. It produces medium to large-sized bulbs with golden-yellow skin and a mild, sweet flavor. Senshyu Yellow onions are versatile and can be used in a variety of dishes, whether raw in salads or cooked in soups and stews.

Key Features:

Cold-hardy and reliable
Medium to large bulbs with golden-yellow skin
Mild flavor, suitable for many culinary uses

Senshyu Yellow is one of the more forgiving varieties, making it ideal for beginner gardeners. Its resistance to cold temperatures and ability to thrive in less-than-ideal conditions make it an excellent choice for overwintering.

2. Radar

Radar is a popular overwintering onion known for its early maturity and cold resistance. It produces round, brown-skinned bulbs that are well-formed and store well after harvesting. Radar onions have a mild, slightly sweet flavor, making them ideal for both raw and cooked dishes.

Key Features:

Early maturing with good cold resistance
Brown-skinned bulbs with a mild flavor
Stores well after harvest

Radar onions are often recommended for gardeners looking for a reliable overwintering onion that can withstand the cold and produce a high-quality crop in the spring.

3. Electric Red

Electric Red is a vibrant and beautiful variety of autumn onion that produces stunning red-skinned bulbs. It has a mild, sweet flavor that is perfect for adding color and taste to salads, sandwiches, and other dishes. Electric Red onions are hardy and well-suited to overwintering, making them a great addition to any garden.

Key Features:

Beautiful red skin with a mild, sweet flavor
Adds color to salads and other dishes
Cold-hardy and ideal for overwintering

The striking appearance of Electric Red onions makes them a popular choice for gardeners who want to add some visual interest to their garden beds while also growing a delicious and versatile onion variety.

4. Troy

Troy is a well-known variety of overwintering onion that is valued for its reliability and resistance to cold weather. It produces uniform, golden-brown bulbs that are medium to large in size. Troy onions have a classic onion flavor and can be used in a wide range of culinary applications.

Key Features:

Reliable and cold-resistant
Uniform golden-brown bulbs
Classic onion flavor

Troy is an excellent choice for gardeners of all experience levels. Its consistent growth and resistance to cold make it a favorite for those looking to grow onions through the winter.

5. Swift

Swift is a fast-growing autumn onion variety that is perfect for gardeners who want an early spring harvest. It produces round, brown-skinned bulbs with a mild flavor. Swift onions are known for their reliability and resistance to disease, making them a low-maintenance option for autumn planting.

Key Features:

Fast-growing with early maturity
Round, brown-skinned bulbs with mild flavor
Resistant to disease

Swift onions are a great option for those who want a quick and easy crop that will be ready to harvest early in the season, providing fresh onions before many other vegetables are available.

6. Shakespeare

Shakespeare is a very hardy overwintering onion that produces large, round bulbs with white flesh and brown skin. It is known for its excellent resistance to bolting, which means it is less likely to flower prematurely, ensuring a good harvest. Shakespeare onions have a strong flavor, making them perfect for cooking.

Key Features:

Extremely hardy with good cold tolerance
Large bulbs with white flesh and brown skin
Strong flavor, great for cooking

Shakespeare onions are a reliable choice for overwintering, especially in areas with unpredictable winter weather. Their resistance to bolting and cold tolerance make them a dependable option for many gardeners.

7. Hi Keeper

Hi Keeper is a variety known for its excellent storage capability, making it ideal for those who want to enjoy their onions long after the harvest. It produces firm, golden-brown bulbs with a classic onion flavor. Hi Keeper is well-suited for autumn planting and can handle cold temperatures well.

Key Features:

Excellent storage capability
Firm, golden-brown bulbs
Classic onion flavor

If you are looking for an onion that you can store and use throughout the year, Hi Keeper is a great choice. Its long storage life means you can enjoy homegrown onions well into the winter months.

8. Snowball

Snowball is a white-skinned onion variety that can be planted in autumn. It produces crisp, white bulbs with a mild, slightly sweet flavor, making it a great addition to salads and other fresh dishes. Snowball is cold-hardy and can handle overwintering well.

Key Features:

White-skinned bulbs with a mild, sweet flavor
Cold-hardy and ideal for overwintering
Great for fresh use in salads

Snowball onions are perfect for those who prefer a milder onion flavor and want to add a touch of brightness to their dishes. Their crisp texture and sweet taste make them a favorite for fresh use.

9. Senshyu Red

Senshyu Red is similar to Senshyu Yellow but with a striking red skin. This variety is cold-tolerant and produces medium-sized, red bulbs with a mild flavor. Senshyu Red is perfect for adding a pop of color to dishes and is versatile in the kitchen.

Key Features:

Cold-tolerant with medium-sized red bulbs
Mild flavor, versatile for many dishes
Adds color to the garden and kitchen

Senshyu Red is an excellent choice for gardeners who want the hardiness of Senshyu Yellow with the added visual appeal of red-skinned onions.

10. Valencia

Valencia is a hardy, overwintering onion variety that is suitable for autumn planting. It produces large, mild-flavored onions and is known for its high yield and good storage quality. Valencia onions are perfect for those looking to grow a large quantity of onions that can be used in a variety of dishes.

Key Features:

Large, mild-flavored bulbs
High yield and good storage quality
Ideal for overwintering

Valencia onions are a versatile and productive variety, making them a great choice for gardeners who want to ensure a plentiful harvest of flavorful onions.

How to Plant and Grow Autumn Onions

Growing autumn onions is relatively straightforward, and with proper preparation and care, you can enjoy a bountiful harvest of fresh onions early in the season. Follow these steps to successfully plant and grow autumn onions in your garden:

1. Preparing the Soil

Onions prefer well-drained, fertile soil with a pH between 6.0 and 7.0. Before planting, prepare your garden bed by removing weeds and adding compost or well-rotted manure to enrich the soil. Onions require good drainage, so if your soil tends to retain water, consider planting them in raised beds.

2. Choosing the Planting Site

Select a sunny location for planting your autumn onions. Onions require full sun to grow well, so choose a spot that receives at least 6-8 hours of direct sunlight each day. Ensure the area is protected from strong winds, which can damage young onion plants.

3. Planting Onions

Plant onion sets or seedlings in late September to early October, depending on your climate. The goal is to allow enough time for the onions to establish roots before the first hard frost. Plant the sets about 1 inch deep, with the pointed end facing up, and space them 4-6 inches apart in rows that are 12 inches apart.

4. Watering and Mulching

Water the onions well after planting to help them settle into the soil. Keep the soil consistently moist but not waterlogged. Adding a layer of mulch around the plants will help retain moisture, suppress weeds, and protect the onions from extreme cold during winter.

5. Fertilizing

Onions are light feeders, but they benefit from an application of a balanced fertilizer during planting. Avoid high-nitrogen fertilizers, as they can promote excessive leaf growth at the expense of bulb development. A slow-release fertilizer applied in the fall will provide nutrients as needed.

6. Winter Care

Autumn onions are hardy and can withstand cold temperatures, but in areas with severe winters, it is advisable to add an extra layer of mulch or straw to protect the plants from freezing temperatures. This helps insulate the soil and prevent frost heaving, which can expose and damage the onion bulbs.

7. Spring Growth and Harvesting

As temperatures warm in early spring, the onions will begin to grow vigorously. Remove any mulch that may be obstructing growth and continue to water the onions as needed. Autumn onions are typically ready for harvest in late May to early June. Harvest the onions when the leaves begin to yellow and fall over.

Pest and Disease Management

Autumn onions are relatively pest-resistant, but there are still a few pests and diseases to watch out for:

Onion Fly: The larvae of the onion fly can damage onion bulbs. Use row covers to protect young plants and prevent adult flies from laying eggs.
Onion White Rot: This fungal disease can cause yellowing leaves and rotting bulbs. Practice crop rotation and avoid planting onions in the same spot year after year to reduce the risk of white rot.
Thrips: Thrips are tiny insects that can damage onion leaves, causing them to turn silver. Use insecticidal soap or neem oil to control thrip infestations.

Conclusion

Growing autumn onions is an excellent way to extend your gardening season and enjoy fresh onions earlier in the year. With the right varieties and proper care, you can have a productive and rewarding harvest. Whether you choose the classic Senshyu Yellow, the striking Electric Red, or the reliable Radar, there are plenty of options to suit your garden and culinary needs. By following the tips in this guide, you’ll be well on your way to growing a successful crop of autumn onions that will enhance your garden and your kitchen.

So why not give autumn onions a try this year? With their cold-hardiness, early harvest, and ease of care, they are a perfect addition to any home garden.