Seed Series: Growing Onions & Shallots in the Garden

  • Difficulty Rating: Beginner
Bare root Walla Walla Onion Starts ready to plant in spring; shown with Fiskars Watering Can

Onions are a staple pantry food in most kitchens.

They add zing and flavor to any number of dishes from raw vinaigrettes to slow-simmered stews. In my own kitchen, I rarely cook a meal that doesn’t include at least one recipe calling for some type of onion. I may need a few snips of green scallion tops to scatter over a finished Thai curry bowl, a slice of red to top a bagel, or a large, chopped bulb to combine with other root vegetables and fresh herbs for a roast. Without onions, most of our meals would taste of something missing.

How to grow onions or shallots really depends on when you want to start, what kind you want to grow, and where you live. Some gardeners prefer to begin with seed. Others choose bulbs. And, many prefer to begin with bare-root starts.

Shallot seed planted in winter under lights

Growing onions from seed is fairly simple. Order your seed in summer or even over winter. In milder climates, seed may be sown directly into the garden in mid-summer; this crop will over-winter, producing large bulbs for harvest the following summer.

If you need to begin indoors during winter or spring, sow the seed into sterile starting mix, under lights by late winter. Allow the seeds to germinate and grow several inches in height. Then, begin snipping back the tops of the greens by an inch or so every few weeks. This will strengthen the roots and encourage stronger plants. Try to protect your snipped seedlings from overhead watering to reduce the chance that those hollow shoots will collect water and rot.

Once the chance of a freeze has passed, move your seedlings (or pick up a bunch of bare-root onion starts at the nursery) to move into the garden. When you plant, be sure to give each small sprout room to grow by dividing individual shoots and spacing them based on your supplier’s recommendations; it will differ based on variety.

Keep your crop well weeded in loose, fertile soil. And, be sure to keep them well watered for sweeter flavors to develop.  As the green tops begin to whither and the shoulders of the bulbs begin to push up from the soil come summer, begin harvesting. If bulbs are crowded, thin your crops by removing every other bulb in order leave remaining bulbs space to grow. And, if your onions try to send up flower stalks, cut out the flowers right away. Try to eat any bulbs that attempted to flower before you eat others. Those that even try to flower may not grow much larger or make for a good storage option.

Kumamoto Oysters on the half shell with Shiso-Shallot Champagne vinaigrette

Shallots, while like onions, are much more mild in flavor and work well with more delicate tastes like light béchamel sauces or in a very mild vinaigrette to spoon over raw oysters. Order shallot seed to sow indoors in late winter or to sow directly into the soil after the chance of a freeze has passed – in much the same manner described for onion seed above. Or, in some locales, choose to plant your shallot bulbs in fall at the time you plant your garlic.

Maturing Onion bed with bulb shoulders beginning to form; Fiskars Big Grip Weeder shown for keeping the bed weed-free

Once the bulb tops of onions and shallots start to dry and the well-formed bulbs have developed thick, dry skins, it may be possible to store them for winter. Whether your crops will store well will depend on the variety you grow and where you live. Some bulb-forming onions, like Walla Walla Sweets, are best eaten within a few weeks of harvest. And, in cool, moist areas like my beloved Pacific Northwest, few homegrown onions will keep in the cellar for more than a month or two at most.

Bunching onions are another culinary favorite. Scallions, as they are also known, can be grown most of the year in many locations. These green onions are a tasty winter harvest option for those gardening in cold but not frigid locations. Plant scallion seeds according to the seed vendor directions by mid-summer, and harvest by the bunch into fall and winter. Just don’t expect to get big storage bulbs from this variety.

Onion choices and ways to start them don’t end here. Some growers prefer to select bags of bulbs from which to start a patch. And, many veggie gardeners look for options to create a perennial allium patch by way of multiplier onions. And, for those looking for a bit of originality and movement in their beds, consider walking onions (edible or ornamental) for fun. Just check with your favorite nursery or seed supplier to be sure your choice is a best fit for your climate. Cultivating the right allium the right way is going to be very different in every gardening climate.