Fall is For Onions: A Guide to Planting Onion Sets in Autumn

As an avid gardener, I’m always looking for ways to extend my growing season and maximize yields from my small backyard plot That’s why I was so excited to discover that many types of onions can be planted in the fall for an early summer harvest the next year!

In this article I’ll share everything I’ve learned about the best practices for fall onion planting. Read on to learn all about

• Why planting onions in fall works
• Timing fall planting correctly
• Choosing the right onion varieties
• Preparing beds and planting properly
• Caring for onions over winter

I’ll also answer some common questions about growing onions in the fall. By the end, you’ll have all the knowledge you need to add fall-planted onions to your own vegetable garden!

Why Plant Onions in the Fall?

Onions are incredibly versatile culinary staples that store well, so they are certainly worth finding space for in the garden. Many types can be planted in fall and allowed to overwinter for a super early summer harvest. Here are some of the main advantages of fall onion planting

• Earlier harvests – Onions planted in fall and wintered over will be ready to start harvesting up to 1 month sooner than spring plantings.

• Larger bulbs – The longer growth period allows fall-planted onions more time to swell into large, juicy bulbs.

• Less maintenance – Since onions are growing over winter, there’s less need for weeding, watering, and fertilizing.

• Soil prep done – Planting in freshly tilled garden beds already prepped for other crops saves time.

• Fewer pest issues – Onion maggots and thrips, two common onion pests, are less prevalent in cooler weather.

If you have space, planting a portion of your onions in autumn makes excellent use of your garden real estate!

Timing Matters – When to Plant Fall Onions

Timing is important when it comes to fall onion planting. You’ll want to plant them 4-6 weeks before your average first fall frost date. This gives them enough time to establish roots before growth shuts down for winter.

In most zones, aim to get onion sets or transplants into the ground in late September to late October. If you’re not sure of your average frost date, you can look it up by zip code here:

https://planthardiness.ars.usda.gov/PHZMWeb/

Onions can withstand quite cold temperatures, even a few degrees below freezing. However, it’s best to provide some protection if extended freezes below 20°F are expected in your area by mulching heavily.

In zones 6 and up, you can sometimes succesfully plant into early November. In zones 1-5, it’s risky to plant much beyond October. Listen to the weather forecast and your gut!

Choose the Right Onion Varieties for Fall Planting

While most onion varieties can be planted in spring, not all do well when fall planted. Choose varieties described as good for overwintering or specifically for autumn planting.

Here are some top types that thrive when planted in the fall:

• Yellow – Copra, Bridger, Golden Bear
• White – White Wing, Snow White
• Red – Red Wing, Red Burgundy

Within each color, look for varieties dubbed “long day” onions. These need the longer daylight hours of spring and summer to bulb up, making them perfect candidates for fall planting.

Avoid short-day varieties like Vidalia or Texas 1015s that only produce bulbs with 10-12 hours of sun – they may bolt in spring before making a bulb if fall planted.

I also recommend ordering onion sets or transplants over seeds – they establish much more readily in autumn.

Preparing Beds and Planting Properly

Since onions have shallow roots, it’s important to prepare a smooth, weed-free, and loamy planting area for your fall crop. Follow these tips:

• Work in 1-2 inches of compost or well-rotted manure a few weeks before planting. This boosts organic matter.

• Rake beds smooth shortly before planting. Onions need firm soil, so eliminate large clumps or stones.

• Plant sets 1-2 inches deep and 4-6 inches apart in all directions. Closer spacing produces smaller bulbs.

• Consider mulching newly planted onions with grass clippings or straw. This conserves moisture and insulates.

• Water thoroughly after planting and continue doing so weekly if rain is lacking. Proper moisture is key!

It’s easy to plant too deep, so don’t bury those sets or seedlings more than 2 inches. Shallow is best! Add a nitrogen fertilizer at planting time and again in early spring once growth resumes.

Protecting and Caring for Fall Onions During Winter

Once snug in the ground, your onions need minimal care as they tough out winter. Here are a few tips:

• Add a 4+ inch insulating mulch layer in late fall after the ground freezes. Straw or leaves work great.

• Consider protective covers like low tunnels or cloches if you face very harsh winters.

• Perforate plastic covers or remove fleece on sunny winter days to prevent overheating.

• Remove mulch in early spring to allow soil to warm. Loosen soil if compacted.

• Weed early and often once spring growth starts. Weeds will compete for nutrients and water.

• Water spring onions weekly if rain is lacking. Consistent moisture is vital for plumping bulbs.

The biggest threats to fall onions are extreme cold and fluctuating freeze/thaw cycles which can heave plants from the ground. Choose hardy varieties and protect with ample mulch!

FAQs About Planting Onion Sets in Fall

Here are answers to some common questions about growing onions in the fall season:

What zones can plant onions in fall?

Most zones 3-10 can succesfully plant onions in fall, though extra protection may be needed in colder regions. Zone 1-2 gardeners should wait for spring.

Do onions need full sun for fall planting?

Yes, choose a spot that gets a minimum of 6-8 hours of direct sun daily. Morning sun is preferable to afternoon.

How long do fall-planted onions take to mature?

Onions planted in fall and wintered over will be ready for harvest in early-to-mid summer, up to 4 weeks before spring plantings.

Should you fertilize fall onions?

Yes, use a balanced vegetable fertilizer when planting in fall and again in early spring when growth resumes.

What if my fall onions start growing in winter?

Some new growth during warm spells is fine, but try to prevent excessive growth by keeping them cool. Growth uses up stored energy.

Grow Bigger, Better Bulbs By Planting in Fall

I hope these tips have shown that planting onions in the fall can help boost yields from this versatile vegetable. Take advantage of your garden’s dormant season by tucking some onion sets into freshly prepped beds this autumn!

With the right timing, variety selection, planting techniques, and overwintering care, you can enjoy an earlier, low maintenance onion harvest. Don’t let that garden space sit idle – fill it with onions this fall.