Fall Onions Made Easy

Best Onions in Fall

Growing fall onions is sometimes confusing – should you choose the long day or day-neutral ones? When should you plant? Does the color of the onion matter? How to avoid growing non-bulbing onions again this year?

Most questions come down to, “What onions can be grown this fall?”

The short answer is the sweet onions will do best in almost all locations, but there is more to the answer! 

Most gardeners can successfully grow the sweet Candy onions for cooking. 

Conditions for Fall Onions

There are three conditions fall-grown onions need – day-length, time to mature and temperature.

Day-length

Candy is a day-neutral onion, meaning it forms a bulb with 12 – 14 hours of daylight. The map above shows approximately where the Candy onion will grow. The southern limits are short day length and the northern are too cold too early for a sweet onion in the fall.  

Our grower has had excellent results in almost all regions of the US. The exceptions are south Florida, south Texas and the extreme northern states bordering Canada. Even parts of Maine have been able to grow good sweet onions in the fall!

Time to Mature

Our sweet onion needs about 90 – 100 days to mature into good sized bulbs ready for harvesting. This is just over three months, so check your freeze dates to see if you’ve got enough time.

Light frosts aren’t a concern with onions as they continue growing until the first hard freeze.

If you aren’t sure of your medium frost dates, take a few minutes to read our article on understanding your frost dates. How to Plan for Fall and Winter Gardening will get you up to speed!

You are looking for the Fall 24°F date (the orange circle) from your local historical weather data.

This brings us to temperature…

Temperature

Onions are remarkably tolerant of frosts and even moderate freezing weather. They go dormant and then resume growth when favorable conditions return. Winter temperatures down to the early 20’s won’t damage onions if mulched and protected.

An old grower once told me some of the sweetest onions he ever grew were over-wintered ones.

He planted bulbs in the early fall, let them grow and mulched heavily 6 – 8 inches deep just before the first frosts. They went dormant in the winter and when spring came he removed the mulch. The onions resumed growing as spring warmed up. He had the earliest harvest of incredibly sweet, delicious onions.

He would never sell these, as they were too special! He shared them with family and close friends.

So – can you grow onions this fall?

You can have sweet onions this fall or early winter if –

• You are not in the extreme southern or northern parts of the US &
• have at least 100 days before your area expects to have a freeze of 24°F (or below).

OR

You can have sweet onions in early winter or early spring if –

• You are not in the extreme southern or northern parts of the US &
• don’t have 100 days before you expect to have a freeze &
• don’t get below about 20°F winter low temperatures.

OR

You can have sweet onions for early spring harvest if –

• You are not in the extreme southern or northern parts of the US &
• don’t have 100 days before you expect to have a freeze &
• do get below 20°F winter low temperatures
• by growing under heavy mulch.

Knowing these 3 factors, you will be more successful growing your onions this fall.

As the famous radio host Paul Harvey used to say, “Now you know the rest of the story!”