While you might not want your winter guests lingering so long, having some Allium cepa for a lengthy stay is another story.
Otherwise known as “overwintering” onion varieties, they are something we northwestern gardeners should consider sowing in our autumn garden plots.
Why plant overwintering onions? If you’re seeking out more succulent, sweet and milder onions for your seasonal menus, then these are for you.
Given our fickle springs, autumn-grown onions often outdo those sown in March-April. Late August through September’s consistently mild temperatures also give overwintering varieties a head start for those frosted starry-filled midwinter nights.
Despite a few challenges, these onions offer not only earlier harvestable bulbs but also have different varieties including perennial Welsh, Japanese, Egyptian Walking onions, and leeks.
Both bulbing and bunching onions can be overwintered. If desired, you can still supplement with spring-sown onions to extend the season.
Unlike their spring counterparts, and given the fact that overwintering onions are sown in autumn, their earlier/sturdier root development ensures they withstand freezing weather. Also, since most of their growth is in early spring when soil moisture is more ideal, they avoid late spring’s fluctuating temps that often result in poor bulbing.
Overwintering onions cure better due to maturing before drying in early summer’s (June-July) long days. Hence, you get more superior onions that will bring you joy for your efforts as well as those tasty bulbs.
Sowing in September is best as the hottest days should have somewhat lessened. For August sowing, select more bolt-resistant varieties to avoid this undesirable occurrence.
Overwintering onions may not only result in superior harvests, but offer seeds that are more vigorous than other types of onions.
To assist sprouting, always purchase quality seed (order from reputable seed companies), and sow only the current year’s seed.
Although sowing can be done directly in open ground, raised beds are preferable. They not only have superior drainage, but more friable soil. Raised beds also hold moisture more evenly; a must for successful overwintering. They help prevent pink root problems (from poor drainage), and promote root health by minimizing nitrogen loss. Ultimately, this means more vigorous bulbs for you to savor earlier. Hoop houses also help manage moisture during the winter.
After sowing seeds about ¼” deep (in a sunny spot with well-drained-amended soil), cover with fine compost or seedling start mix. Water thoroughly and keep consistently moist. After sprouted seedlings are about 3”-4” tall, you should thin them accordingly to the varieties you’ve sown since overcrowding can result in poor plants. Ideally, you want your plants about ¼” diameter going into the winter.
Onions start regrowing in late January-February. Once growth starts, side dress with blood meal then again in mid-April. Use a complete balanced fertilizer in mid-May.
Once tops start to turn golden (except for bunching onions that should be harvested while still green earlier in spring), stop watering for about two weeks before pulling bulbs.
You’ll surely be grateful should you venture sowing onion seeds in autumn so you can soon enjoy some lovely sweet-succulent overwinter onions in early spring.
Seed Sources:
Territorial Seed
They have Red Spring, High Keeper, and White Lisbon bunching onions
Johnny’s Selected Seeds
They have T-448, Bridger, Desert Sunrise, and Walla Walla
Bandit organic leeks
Resources:
OSU dry bulb onions Western OR Dec 2012:
Onions, Dry Bulb — Western Oregon
Johnny’s Seeds overwintering trials:
Overwintering Onions from Seed
High Mowing Seeds’ Time to Plant Fall Onions for Overwintering!
Time to Plant Fall Onions for Overwintering!
Recipe:
Caramelized Spring Onions and Peppers
1 ½ pounds spring onions (bunching, regular onions or a mix of both) red and/or yellow: washed, roots and skin removed, then sliced in 2” pieces for bunching and thin crosswise slices for regular onions
2 large sweet red, orange, yellow or mixture of peppers, washed, stemmed and seeded, then thinly sliced lengthwise
1 teaspoon fresh rosemary, minced
1 teaspoon fresh lime or lemon thyme, minced
1 ½ tablespoons cooking olive oil
¼ cup each sweet sherry wine and organic apple juice
2 tablespoons organic apple cider vinegar
2 tablespoons honey
1/8 teaspoon sea salt
Fresh ground pepper to taste
Heat oil in heavy-lidded sauté pan until it’s hot but not smoking. Toss in onions, peppers, rosemary and thyme. Cook over medium heat until limp, about 5-8 minutes. Remove from heat and gradually add wine, apple juice vinegar, honey and sea salt. Stir to mix, then return to medium heat, stirring until it bubbles. Cover with lid and continue cooking on medium-low for about 15-20 minutes until liquid has concentrated into a glaze and onions are a golden color. Serve hot or cold as a relish on burgers, sandwiches or as a salad topper on seafood, poultry, or vegan dishes.
Store in fridge.
Oregon State University Extension
