If you’re looking to extend your harvest season and enjoy fresh flavors even in the colder months, you might be asking what are winter onions. These cold-hardy garden vegetables are a fantastic, low-maintenance option for gardeners in many climates. They offer a reliable harvest when little else is growing, providing green tops and bulbs from fall right through to spring.
Unlike standard onions, winter onions are planted in the fall and survive freezing temperatures. They establish roots before the ground freezes, then go dormant. When the days begin to lengthen again, they are some of the first plants to wake up and start growing. This gives you a very early crop, which is a wonderful treat after a long winter.
What Are Winter Onions
This term “winter onions” doesn’t refer to a single specific species. Instead, it’s a category that includes several types of onions known for their ability to withstand cold. They are typically planted in autumn and harvested in late spring or early summer of the following year. Their secret is a robust root system and a growth habit that pauses during the deepest cold.
There are a few main kinds you’ll encounter:
- Egyptian Walking Onions (Topset Onions): These are perennials that produce small bulbils at the top of their stalks in summer. The stalks eventually bend over, planting the bulbils to start new plants—they “walk” across your garden. You can harvest the underground bulbs, the tender stalks, and the topset bulbils.
- Multiplier Onions (Potato Onions): These onions grow in clusters of bulbs from a single planted bulb. You harvest the whole cluster in summer, save some bulbs for replanting in the fall, and eat the rest. They have a excellent, strong flavor.
- Some Onion Sets Sold for Fall Planting: Many garden centers offer specific varieties of onion sets labeled for autumn planting. These are usually short-day or day-neutral varieties selected for winter hardiness.
Why Grow Winter Onions?
The benefits of adding these vegetables to your garden are numerous. First, they give you a head start on the season. While you’re still planning your spring garden, your winter onions are already in the ground and growing. They also help maximize your garden’s productivity by utilizing space during the off-season.
They are remarkably low-maintenance. Once planted in the fall, they require very little care until harvest. Their early growth helps suppress weeds, and they can be a great companion plant. Furthermore, they are generally more resistant to pests and diseases compared to spring-planted onions, partly because they avoid the main lifecycle of many onion pests.
Choosing the Right Variety for Your Climate
Not all winter onions are suited for every zone. It’s crucial to select a type that matches your winter conditions. Egyptian walking onions are among the hardiest, often surviving winters in zone 3. Multiplier onions are also very tough but may need a thick mulch in the coldest areas.
If you’re purchasing sets, always look for varieties specifically recommended for fall planting in your region. A local nursery or cooperative extension service is your best resource for this information. Don’t assume that any onion set will survive the winter; using the wrong type can lead to disappointment.
Hardiness Zones and Timing
As a general rule, winter onions are best planted 4-6 weeks before your first hard freeze. This gives them enough time to establish roots. In zones 6 and warmer, you have a wide range of options. In zones 5 and colder, focus on the most hardy types like Egyptian walking onions and provide consistent mulch cover after the ground freezes.
How to Plant Winter Onions Step-by-Step
Planting is straightforward. Follow these steps for success.
- Choose Your Site: Pick a spot with full sun and well-draining soil. Onions hate having “wet feet,” especially in winter, as this can cause rot.
- Prepare the Soil: Work the soil to loosen it and mix in some compost or aged manure. Onions are not heavy feeders, but they appreciate good soil structure. A slightly neutral to slightly acidic pH is ideal.
- Plant Your Bulbs or Sets: Plant individual bulbs or sets about 1 inch deep and 4-6 inches apart. Rows should be spaced about 12 inches apart. The pointed end should be facing up. If planting bulbils from walking onions, plant them just under the soil surface.
- Water Thoroughly: Give them a good watering after planting to help settle the soil and encourage root growth.
- Apply Mulch: Once the ground has frozen slightly, apply a 2-4 inch layer of straw, shredded leaves, or another loose mulch. This prevents the freeze-thaw cycles that can heave the bulbs out of the ground. Don’t mulch too early, as it can attract rodents looking for a warm home.
Caring for Your Crop Through the Seasons
After planting, your main job is to wait. In early spring, as the soil warms, growth will resume. Gently pull back the mulch to allow the soil to warm faster. You can start harvesting green tops as soon as they are a few inches tall—just snip what you need.
Keep the area weeded, as onions don’t compete well. Water if the spring is unusually dry, providing about an inch of water per week. They generally do not need extra fertilizer if your soil was prepared well at planting time. Over-fertilizing can lead to lots of leafy growth but smaller bulbs.
When and How to Harvest
You have two main harvest options. For a continuous green onion (scallion) harvest, simply pull entire plants as needed, thinning the row. For full bulb harvest, wait until the tops begin to yellow and fall over naturally in late spring or early summer.
Once tops have fallen, you can bend over any remaining tops to signal the bulbs to stop growing. Lift the bulbs gently with a garden fork on a dry day. Let them cure on the soil surface for a day or two if weather permits, then move them to a warm, dry, airy place to cure completely for storage.
Common Problems and Simple Solutions
Winter onions are trouble-free, but a few issues can occur. The most common problem is rotting bulbs, usually caused by poor drainage. Always ensure your planting bed does not stay soggy. Onion maggots can be an issue in some areas; rotating your onion bed each year is the best prevention.
If you notice the bulbs being pushed out of the soil in winter (frost heave), just gently press them back in and add more mulch. Birds sometimes peck at young greens in spring; a simple row cover can deter them if it becomes a problem.
Saving and Replanting for Perpetual Harvests
One of the best features of many winter onions is their self-sufficiency. For Egyptian walking onions, simply leave some of the topset bulbils to fall and plant themselves, or collect them and plant where you want. For multiplier onions, save some of your harvested bulbs—the medium-sized ones are often best—and replant them in the fall.
This cycle means you only need to buy planting stock once. You’ll have a sustainable source of onions year after year, which is very rewarding and economical. It’s a great way to become more self-sufficient in your gardening.
Using Winter Onions in Your Kitchen
These onions are versatile. The young green tops are perfect for salads, soups, and as a baked potato topping. The mature bulbs have a robust, pungent flavor that’s excellent for cooking. The small bulbils from walking onions can be pickled or used like pearl onions in stews.
They store well after proper curing. Keep them in a cool, dark, dry place with good air circulation. Mesh bags or braided strands work perfectly. Remember to always set aside your best bulbs for your next fall planting.
Integrating Them Into Your Garden Plan
Think of winter onions as a garden placeholder. They occupy space that might otherwise be empty, improving soil structure with their roots. After you harvest the bulbs in early summer, that bed is now free for a quick crop of bush beans, lettuce, or other summer vegetables. This sucesion planting makes excellent use of your garden real estate.
FAQ About Winter Onions
Can I grow winter onions from seed?
It’s possible but less common and more challenging than from sets or bulbs. Seeds need a very long season and may not establish sufficiently before winter. Using sets or bulbs is the recommended and easier method.
Are winter onions the same as green onions?
Not exactly. “Green onion” is a harvest stage (the immature plant), while “winter onion” refers to the planting time and hardiness. You can harvest winter onions at the green onion stage, or let them mature into full bulbs.
Will winter onions survive a snow cover?
Yes, snow is actually an excellent insulator and protects the plants from extreme temperature swings and drying winds. A consistent snow cover is often beneficial.
Can I plant store-bought onions?
It’s not recommended. Grocery store onions are often treated to prevent sprouting and may not be varieties suited for overwintering in your climate. They also might carry diseases into your garden soil.
What’s the difference between short-day and long-day onions in winter planting?
This is critical. In southern states with mild winters, short-day varieties are typically planted in fall. In northern states, the hardest long-day or day-neutral varieties are chosen for fall planting. Always check the variety’s recommendation.
Adding winter onions to your garden plan is a simple way to boost your yield and enjoy gardening for more of the year. With minimal effort, you’ll be rewarded with a hardy, tasty crop that bridges the seasons. Give them a try this fall and see the benefits for yourself.