How To Grow Onions

Onions are one of the primary ingredients in the classic mirepoix, but even without the other ingredients, there aren’t many things that get my stomach rumbling like the smell of onions sauteing in butter. Add some garlic and it’s a pretty perfect combination.

Of course, not everyone shares my taste, but if you can put up with the tears and stinky breath (and your spouse can as well), and you have a garden plot, then you should absolutely grow some yourself. Because, as with everything else, nothing quite beats homegrown, so if you’re interested in how to grow onions, read on!

How To Grow Onions

Onions can be a little finicky. I’ve certainly struggled to get decent output from them over the years. Relative to other vegetables that you can grow, they’re probably not beginner-level: they’re pretty picky with their requirements, and if you’re not meeting all their needs perfectly, you’ll know.

Getting Started

When thinking about how to grow onions, a lot of people are probably most familiar with the onion sets that you can find in many garden centers. Sets are essentially baby onions that have had their growth interrupted, so that when you plant them, they start growing again into bigger onions. However, because onions are biennial (meaning they flower in their second year) and these sets are entering their second year, it’s possible that they won’t actually get any bigger and just start flowering.

So while sets are probably more common, starting from seed is probably your best bet. Not only do you get to choose from way more varieties, your onions will probably end up bigger and better.

When it comes to planting seeds, onions start early, and are usually the first ones that I plant each year. They can be transplanted outside very early, so they can be started inside even earlier (often early- or mid-February here in Ohio). The process is the same as any other seed – light planting mix, keep moist – so at this point in their lives, onions aren’t really any more difficult than any other vegetable.

Care And Feeding

When it comes time to transplant, which can be done in very early spring, at least 4-6 weeks before your last frost, gently remove the seedlings from the planting container. Make a small hole and plop the seedling in – they can be buried a bit deeper than they were growing, so don’t be afraid to cover some of the stem; just don’t go crazy with it. At this point, some people also like to pinch off the growing tip from the top of the stem. This can encourage the plant to start to develop roots and get stronger instead of continuing to just grow taller.

Okay, so they’re planted outside. Now’s when they start to turn into moody teenagers. Onions are heavy eaters and drinkers. If you think about it, most of the bulb is water, so they definitely need to be watered regularly if it’s not raining enough. A top dressing of compost once a month is probably sufficient for feeding, unless you have a very rich soil to begin with.

Onions also don’t handle competition very well. If you let the onion bed get overgrown with weeds, you might as well just throw in the towel. I know it’s not fun, but you have to keep up with the weeding around the onions, otherwise your harvest will be very slim.

So although it sounds intimidating, and will definitely take more time than other vegetables, all you really have to do is keep up with food, water, and weeding. An easy way to save yourself some effort is to mulch around them – this will help retain water and keep weeds down.

Harvest Time

As the onions grow (and the bulbs hopefully get bigger and bigger), eventually the tops will start to yellow and fall over a bit. At that point, you can just bend the tops over completely to help encourage the final ripening process. When the tops are completely brown, gently pull the onions out of the soil. Ideally, you do this on a dry day, with dry days in the future, because onions need to cure (dry out) before storing. In a perfect scenario, this means that you pull them, then simply let them sit on the soil for a few days while they dry. If it’s rainy and you need to get them up. you can lay them on a screen and keep them in a dry area. Clip the roots and everything but the top couple inches of the stem, and after several days, they should be ready for storage. If you’re using them all immediately, then don’t worry about any of this, but for storage, they’ll need some prep.

Depending on the variety you’re growing, they can store from a few weeks to several months, so be aware of that and remove any bad ones that develop, or they can ruin the whole batch.

And that’s it. When you’re first learning how to grow onions, it can indeed be a little work, but the payoff is worth the effort!