When the frozen garden stares back at you this time of year, thinking about all those onion sets stashed in the garage evoke a certain sort of panic. The truth: Onion-planting is among the simplest crops to grow propery, as long as you do it the right way.
Like bulbs, onions appear bulb-like on the outside. But unlike bulbs, they’re more like long-term investments. They requires minimal care from us up front, and then light does all the hard work.
How to Grow Onions
There are three possible starting points for your onion crop, transplants, seed, or sets (small dormant bulbs dropped in ground). Know what you’re working with: Each one impact how much work will go into your crop, and when it’ll yield a harvest.
Seed means the biggest selection, which is important if there’s a certain color or flavor you seek. Sets get you the quickest road to your harvest (ideal if you live in short growing-season region, or want something before dog days of summer set in), but you don’t have as many options than seed. Transplants split difference between variety and fast-growing time. Most first-time gardeners opt for the sets route; no seedling trays or even a greenhouse are required.
All you’ll need is a sunny place (six-plus hours daily) and some loose soil to work in. The biggest thing of all is timing. As visual guide illustrates, up North we plant in spring; down South, folks tend to do so in fall.
Why? It is biology, not habit. Onions respond to day length… Not simply to heat, in order to start bulbing. Plant a long-day kind down South, and it won’t ever get around to forming a good bulb. It will stretch out all summer, producing only a mass of greenery. That is the first mistake people makes when growing onions.
Match your latitude to the day-length type. The chart includes lists of zone bands where each variety (such as Vidalia or Yellow Storage) can be planted. Look at the list, and see if you’re in a short- or long-day zone. If not, what happens? You’ll harvest onions, but they’ll turn out to be scallions. Learning a lesson the hard way is frustrating.
Next: Use spacing for control. Once you’ve got the variety dialed-in, when do you space? Again, look at infographic. Spacing changes what you’re aiming for in the row, like bulb-to-bulb or onion-to-onion, as shown by each example. For example, with pearls and bunching greens, you can crowd things in more closely. With giant storage onions…you guessed it, you go wider and let ’em stretch out (about five or six inches apart). It’s about quantity versus size. Go narrow for greens; go wide to grow bigger bulbs. It is more like steak versus stew: both are great, but they requires different prep.
The onions are noticing that most of us are lazy about soil prep, it’s where they do not want their feet soggy. Raise the bed if your garden is heavy clay; onions has shallow roots that rot in standing water. Shoot for a pH around 6-7; slightly acidic to neutral, so they can take up nutrients well. Turn in finished compost into the top eight inches before planting time. No fresh manure! Too much nitrogen early promote soft, lush tops that don’t store well. You want dry necks and firm skins for storage. You’ll do better with moderate amounts of nitrogen early, then ease off as the bulbs starts to swell. At that point, phosphorus and potassium will serve you better.
Watering is steady but unglamorous. It’s about an inch a week, not something fancy, just regular water. An inch weekly is right. Use less after high summer when their foliage begins flopping over. You can tell them to go dormant by stopping top growth.
Leave them out in the heat and sun to cure for several weeks through July and August. No hurry. You get a big payoff from a small crop. When it’s still cold outside, you plant; then come the days of the cicada song and on your shelves sits piles of those pungent, dried-up bulbs.
Patience is part of the trick. So is understanding which day-length type to choose; then again, it’s about letting the seasons take over. Let them be, and be amazed at how big they gets.