In the Garden: How to grow onions

It seems like no matter which savory dish I make, onions always play a prominent role. They are easy to grow, so let’s take a look at how to have the best results with them.

Onions are a cool-season crop. Since we’re now past the middle of April, it is safe to plant them in the garden. There are three ways to grow them: from seeds, sets (small bulbs) or young plant starts. This year, a lot of folks are interested in growing a garden for the first time. While that warms my heart, it also means it might be challenging to find sets or plant starts in local garden centers or online.

Before you purchase anything, there is an important fact to know. Onions are divided into types (short, intermediate and long day) based on the number of daylight hours a region receives during the growing season. Since the Inland Northwest is treated to blissfully long days during the spring and summer, that means we should all be growing long-day onions. Examples of varieties that grow well here are Ailsa Craig, Copra, Highlander, Italian Red Torpedo, Patterson, Red Wing, Ringmaster, Walla Walla Sweet and Yellow Sweet Spanish.

If you’re starting your onions from seeds, sow them directly in the garden 1/4-inch deep. Plant sets so there is 1 inch of soil above the top of the onion bulb. If you were lucky enough to find plant starts, bury the bottom inch (the root end) in the soil.

When it comes to spacing, plant seeds 1 to 2 inches apart, sets 2 inches apart and onion starts 4 inches apart. Space the rows 8 inches apart. Seedlings and onions growing from sets will eventually need to be spaced 4 inches apart. To accomplish this, harvest every other onion to provide the remaining onions with enough room to grow and mature. Be sure to use those thinned onions in your kitchen.

During the season, pull weeds so they won’t compete with the developing onions for nutrients or moisture, and be sure to water the bed on a regular basis. It’s important to avoid stressing the plants because that can impact how well the bulbs grow and how long they’ll keep in storage.

Harvest onions any time during the season: as scallions (green onions), as small onions or when the bulbs are full-size. If you are growing them to store for later use, wait until the stalks fall over, which indicates the plants have finished growing. Turn off the water to the bed, pull up the onions and move them to a sheltered area such as under a carport or in a shed until the skin is papery dry.

To store mature onions that have gone through the drying process, place them in a cool, dark location. We keep ours in the basement where it stays between 50 and 60 degrees for most of the winter. When it comes to the amount of time onions will keep in storage, it varies widely between varieties. For example, sweet onions only have a storage potential of one month, so use them up first. At the other end of the spectrum, Copra onions will usually keep 10 to 12 months in storage.

No matter which variety you grew, remember that if you’re not using up the onions quickly enough, it’s also possible to chop them up, place them in freezer bags and freeze them to use later.