Why Fall Is The Best Time To Plant Onions

Spring is often associated with new life after the cold of winter. The soil is warming up and, of course, April showers bring May flowers.

But spring can also be a continuation rather than a starting point. Instead of planting your onion seeds at the beginning of spring, for example, try planting them in the fall!

Fall is actually the best time to plant onions because, unlike other plants, onions can survive winter by going dormant. Fall planting can result in larger crops, faster maturity, and stronger roots.

Read on to not only find out why it’s smart to plant onions in the fall, but also how to do it! These tips and tricks will help you get ahead of the game when it comes to your onion harvest.

5 Reasons You Should Plant Onions In The Fall

Onions can overwinter better than many other plants, but how do they do it? And why is planting onions in the fall worthwhile in the first place?

This guide will help you understand the ins and outs of fall onion planting and its benefits.

1. They Can Survive Cold Temperatures

Most plants do well with sun and warm temperatures – everything that fall and winter do not have. In fact, the first frost usually finishes off your dying summer crops.

Onions, however, are very sturdy vegetables and can survive through the freezing temperatures of winter with a little help. They won’t produce during this time, but instead, lie dormant until the temperatures rise again.

2. Their Roots Get A Head Start

Before they go dormant, onions do begin to spread their roots if you plant them in the fall. That means that when the soil warms up again, onions have a head start in the spring growing process.

By not having to plant, you save previous spring growing time. Not only that, but the onions also already have their roots started.

You’ll get your onion crops much sooner if you plant in the fall.

3. The Soil Is Still Warm

Onion roots don’t sprout in the fall just because of the extra time. It’s also because the soil is already a good, warm environment for them.

In the spring, you have to dig up the ground for onions as soon as possible after the first frost. That means that, while the danger of freezing should be over, the soil is still pretty cold.

When you plant onions in spring soil, it can take a little while to get going as the soil warms up.

But fall soil is still warm! By planting your onions in the fall, you’re taking advantage of residual summer warmth.

Your onion seeds or sets will germinate much faster than they do in the spring.

4. You’ll Get Bigger Onions In The Spring

Jumpstarting your roots doesn’t only make your onions grow faster, it also helps them grow larger.

During spring, the conditions for growth continue to get better and better. The soil warms up, there’s more sunshine, and there’s more moisture.

Spring is when onion plants can really kick into overdrive. Normally, they would have to spend this spring energy growing roots as well as the onion bulbs themselves.

If you plant in the fall, their roots are already started by spring, and they don’t have to spend as much energy on them. In turn, the plants can spend that energy on growing larger onion bulbs.

5. The Onions Will Mature Faster

Typically, if you plant onions at the beginning of spring, they’ll be ready for harvest by late summer. They could even take until early fall.

But if you plant them in the fall, you could have a viable crop of onions by June! In short, planting early means you can harvest early.

Seeds Vs. Sets

Before you begin your fall planting, you should decide whether to use seeds or sets.

Onion sets are immature (small) onion bulbs that have already been started. They are then dried to halt their growth.

The obvious advantage of onion sets is that they take less time to mature in the ground. They’re also much more likely to take root than seeds, which may not germinate at all.

However, onion sets are more expensive than seeds, and sometimes hard to find. You can grow your own onion sets, but this requires much more time and planning.

Seeds are the easier and cheaper way to go, but they also need more time.

You should plant seeds a full four weeks before you plant sets. You also have to densely seed your bed since onions can be difficult to start.

In the end, it comes down to what’s available in your area and your gardening budget.

How To Plant Onions In Fall

Planting fall onions can be beneficial, but it does take a little more work than planting in the spring.

Follow these steps to protect your onion plants during the winter for a bountiful – and early – summer harvest.

What You’ll Need

  • Garden trowel
  • Hand cultivator rake
  • Gardening gloves
  • Onion seeds or sets
  • Knife
  • Straw mulch
  • Water

1. Prepare Your Garden Bed

First, choose a spot for your onions where they’ll get full sun come springtime. Onions need sun for most of the day to grow full crops.

Once you have your location, begin preparing the bed by tilling the soil with a hand rake. This will remove any unwanted debris such as rocks or old roots.

Till down to between eight and ten inches. Onion sets need at least four inches of space between them, while seeds need about eight. If you’re planting more than one row, put a foot of space between each.

Calculate how much bed space you’ll need according to how many onions you plant.

Spread an inch or two of compost over the tilled bed. Onions are hungry plants and need plenty of organic matter in their soil. Work it into the soil with your rake to aerate the soil.

Dig holes for your sets or seeds about an inch deep into the soil. They should be four to eight inches apart (for sets and seeds, respectively).

2. Sow Your Seeds Or Sets

If you’re planting using onion seeds, sprinkle several seeds into each hole. You want to seed densely to increase the chance of germination.

Once the seeds are growing strong, you can trim away the weakest and thin out the crop.

If you’re using onion sets for your fall planting, place them in the holes with the pointed tip face up.

Cover holes with a mix of soil and compost. The tips of your onion sets should barely be poking up out of the soil.

3. Check Your Soil’s Moisture

Onions need soil that is moist for the first few weeks of fall growth. 

If your soil is on the dry side when you plant, water it just enough to keep it damp but don’t oversaturate.

4. Check Your Soil And Cover Your Bed With Mulch

Check your soil’s moisture level once again; if you have drier soil, you can water lightly again after adding the mulch.

Add an inch or so of straw mulch over the top of your garden bed. Keep an eye out for any sprouts in the next couple of weeks.

Once the onions start greening, you can add another few inches of mulch.

Be careful as you cover the bed, so you don’t damage the sprouts. Straw mulch is best because it’s not too heavy but will still insulate your onions during the winter.

5. Water Until The First Hard Frosts

If you live in an area with frequent rain – say, once a week – you don’t really need to water your onions yourself. Let nature do the work for you.

If you’re in a drier climate, you can water about once a week to keep the soil moist. Once you’ve had a couple of hard frosts or your first hard freeze, you can stop watering altogether.

By this point, your onions will have fallen dormant, and your fall work is complete.

6. Spring Maintenance And Summer Harvesting

Once you see those little green sprouts start growing again, it’s time to shift into spring maintenance. Keep your onion beds clear of weeds and immediately clear any bolted, flowering stems.

If you planted using seeds, keep an eye on the growth of the shoots in the spring.

Once the onion shoots are about two inches tall, trim away the weakest ones with a knife. You should have nice and neat groups about four inches apart.

Your onions should be ready to harvest by about June, a couple of months earlier than spring-planted onions!

You can harvest them at that time or allow them to grow until the tops become yellow and bend. This means they’re done growing and you should have large, tasty onions below.

Extra Tips For Planting Fall Onions

Here are some bonus tips on how to plant fall onions, from which varieties work best to when to plant.

When To Plant Your Fall Onion

Your fall onions need at least four to six weeks to grow before the first hard freeze or heavy frost makes them dormant.

Keep an eye on the weather forecasts and plant according to your starting style. If you’re using onion sets, you can plant about a month ahead of the frosts.

On the other hand, onion seeds need at least six to eight weeks of growth before dormancy.

Choose The Right Variety

Not every onion variety is good for planting in the fall. It all depends on where you live.

There are different breeds of onions that can handle different day lengths. These fall into the categories of short-day, long-day, and day-neutral or intermediate varieties.

If you live below the 36th parallel (North Carolina or further south), you should grow short-day varieties. These include:

  • Crystal Wax White Bermuda
  • Hybrid Yellow Granex
  • Red Burgundy
  • Southern Belle
  • Stuttgarter
  • Texas 1015-Y Supersweet
  • White Bermuda

For those of you north of the 36th parallel, try these long-day varieties:

  • Ailsa Craig
  • Buffalo
  • Copra
  • First Edition
  • Red Florence
  • Red Wethersfield
  • Yellow Sweet Spanish

You can also try day-neutral or intermediate varieties no matter where you live north or south:

  • Candy
  • Red Stockton
  • Super Star

Choose Smaller Sets Over Bigger Ones

Using onion sets is a convenient way to plant in the fall. But knowing which sets to use can give you a real leg-up with your growing.

You’ve likely heard the phrase “bigger is better,” but this isn’t true for onion sets! Onions have a tendency to bolt, or shoot up flowers before they’re mature, leading to small and unappetizing bulbs. 

Larger sets are more likely to bolt because they’re already so far along in the growth process. Smaller ones are less likely to bolt but will still mature in time for an early summer harvest.

In Conclusion

Even though spring is the more common time for gardening, consider giving fall a chance for planting your onions.

You don’t have to worry about your onions dying in the cold of winter, because they fall dormant around the first heavy frosts. This means that when spring comes around again, your onions will wake back up and be ready to keep growing.

So, take advantage of the extra time fall provides by starting your onions before winter hits, not after. You’ll end up with a crop that’s mature by summer and even more robust by the usual late summer harvest!