With Fall upon us it’s time to consider planting onion sets in your garden(s) in growing zone 8b in the Pacific Northwest. Onion sets go quickly, so grab as soon as they show up. I buy mine online from a trusted source, Irish Eyes, who grows in Eastern Washington. I prefer to not buy onion sets in person unless you know they just came in. Otherwise, if left inside in a warm store they can go soft quickly. (Or worse, the farm store hid them in the back, leftover from Spring. Make sure the onions feel firm and are not sprouting.)
Planting onions in early Fall can lead to larger onions at harvest time, and that they are ready weeks before Spring planted ones are. Typically I start my onions from seed, in late February into the end of March, depending on the variety. A Walla Walla onion can take 120 days to harvest, so you have to plan it out. Seeding is tricky as well, balancing light and warmth to germinate and be ready to plant in the garden by end of April. Add in the planting of tiny seedlings is a pain in the rear I do every year (and of course, I’ll do it again every year to have my beloved Walla Walla onions). (And yes, you should learn to grow onions from seeds, it’s a skill to have. But there is no issue with making it easier on yourself and having less to do in late Winter.)
(Tiny, tiny seedlings in mid April)
But with Fall planting of onion sets, you can walk away and just forget about it, as one does with garlic. And the planting of onion sets is exactly the same as garlic. They are nearly the same size as well. An onion set is just a cocktail sized onion, ready to grow. You can also sometimes find onion starts, in soil cups, as well this time of year. Just plant like you would a seedling in Spring. Often these will be Walla Walla or similar sweet onions that grow big. If you buy these, plant and carefully place straw around them. They will sleep through the Winter as well.
Determine which onions you want to grow: In our grow zone, we use long-day onions, so be sure to remember that, in the Pacific Northwest we have long hours of sunlight in summer (for our homestead we top out at 16½ hours in summer). The onions start forming bulbs as we cross 14 hours daylight in late Spring.
Think how many onions you want to harvest. You will be harvesting over time, picking young ones for dinner, then finally pulling and curing the remaining ones. Always grow more than you think you will use. See below for spacing.
Figure where you want to plant your onions: If your ground water level is high, deep raised boxes can be your friend. Since your onions will be over wintering, you don’t want it sitting in water and potentially rotting. Think about if rain water sits in the area, or does it sink in quickly. Raised rows also work well. Make sure your onions will receive as much sun as possible in summer.
Once situated: Weed the bed well, turning it over gently. Add soil or compost as needed on top.
Spacing and planting: I do rows 1 foot apart and as our beds are 30″ wide, I can fit 5 onions across. Our rows are a shy 100 ft long each. You want at least 6″ apart per onion, for ample growth. As you can see, we grow quite a few!
(That is my antique dibble)
Using a dibble or a broomstick: Poke the holes into the soil. Drop a single onion in, bottom down, and cover with dirt, gently tamping down the soil. It doesn’t need to be a deep hole, just enough that the onion is covered.
Cover your onions with straw deeply. Water the straw to hold it down, then walk away for the fall and winter. Unless your fall is hot, don’t worry about watering.
In late winter to early spring the onions will come alive once again, and push up through the straw, green stalks rising up. As the weather heats up, you will want to keep it well watered so it grows large.
(No straw in summer, and boy the weeds were fun….)
You will know when to harvest when the tops start turning tawny in color and the onion is looking good sized about the dirt. To harvest, pull gently up to pop out. If the top breaks (and it does a few times at least) gently use a small hand shovel to loosen under the roots, being careful to not gouge the onion.
To cure: Shake dirt off of the onion, especially on the roots (which I trim) and gather all the onions. Trim the stalks back, leaving 12 or so inches. Place it in an airy spot, out of the sun for a couple of weeks. We place a wood pallet over a garden cart in our shop, and walk away. The pallet ensures air flow, and the dirt drops down as the onions dry. Once cured, we trim the stalk back even more.
To store for use: We keep ours on the pallet. We have a cellar that is 55* year round and use this to store it in, or use our shop. The key is keep it cool, in the dark, and no moisture. Always look through your stored onions when grabbing one to cook. Check quickly for any spoiling, and toss those in the compost pile. We use our sweet varieties first, then get into the white and yellow ones that are standard onions. And keep onions separate from your other stored vegetables, particularly potatoes.