When to Plant Onions?

Onions are a cold-season crop that is quite hardy and therefore easy to grow. But when should you plant them and should you raise them indoors and transfer them outside later or can you plant them outside right away? Here are the best practices to get a successful and bountiful onion harvest!

So when to plant Onions? In short, if you want to plant Onions directly outside then plant them in the late fall or winter if you are living in a milder region. If you are living in a region with a very cold winter then plant your Onions in late March or April or you can raise them indoors and transfer them outside later on.

What Kind of Variants are There and Do the Planting Times Vary?

While some onions can only be planted during spring, there are varieties that need to be planted in a different season. There are three categories of onions, and each has its own benefits that make it good for different regions.

For Zone 6 and colder regions, like in the north of the US, the summer days are longer and are perfect for the long-day variety.

Zones 7 and warmer, like the south of the US, don’t have a long wintertime, which makes these regions perfect for the short-day variety.

Then you have the day-neutral variety, which is good for any zone but best suited for Zones 5 and 6.

Short-Day Onions

These onions will form bulbs under 10 to 12 hours of daylight, which is why they are best suited for southern regions.

They need a winter climate that is mild. They grow best in Zones 7 or warmer.

The short-day Onions are usually planted in the fall and they will be fully mature in late spring.

You can plant them in northern areas but you will get much smaller bulbs. Short-day onions will reach maturity in 110 days.

In cooler areas, if planted in the spring, they will mature in about 75 days.

Short-Day Onion Varieties:

  • Stuttgarter – Yellow with a slightly flat shape
  • White Bermuda – A very mild flavor with white thick, flat bulbs
  • Red Burgundy – Red-skin and white bulb, with a sweet mild flavor
  • Crystal Wax White Bermuda – Pearl-sized onions that are often used for pickling
  • Hybrid Yellow Granex – Sweet flavor
  • Southern Belle – Both skin and flesh are a ruby red color
  • Texas 1015-Y Superswee – A very sweet flavor that does well for storage

Long-Day onions

This variety does best being planted during the winter or early spring.

They will mature within 90 to 110 days and need at least 14 to 16 hours of daylight.

This makes them good for growing in northern regions that are colder.

They are perfect for storing.

Long-day onion Varieties

  • Sweet Yellow Spanish – A yellow/white bulb, round and large
  • First Edition – These have a high-yield, stores very well has a creamy yellow color and is very flavorful
  • Red Wethersfield – Red-skinned with white flesh, these have flat bulbs and store very well
  • Ailsa Craig – These tend to have huge bulbs and are often used for garden exhibitions
  • Buffalo/Norstar – These aren’t good for storage, as they don’t keep long after they have been harvested, but the produce onions quickly
  • Copra/Southport Red Globe/Sweet Sandwich/Yellow Globe – These all store well and have oblong-shaped bulbs

Day-Neutral Onions

These onions need 12 to 14 hours of daylight to form bulbs.

They tend to be planted in the autumn where the winter is milder, or in the spring for colder climates.

This variety of onion is super sweet, will mature in 110 days and does best in growing zones 5-6.

Day-neutral Onion Varieties

  • Red Stockton – a large onion with red rings and white flesh
  • Super Star – very large white bulbs and a sweet flavor

What are the Hardiness Zones?

A hardiness zone is a geographical zone, that is defining a certain range of climatic conditions. These conditions are relevant for growing plants and they are used to define what kind of plant can grow at wich geographical location and also when to plant a specific plant in a given zone.

There are 13 zones that range from 1, which is the coldest zone, all the way to 13, which is the warmest zone.

There is a plant hardiness zone map from the USDA that shows the different zones in the US.

You can find it by following this link.