Most of us have a row or two of onions in the garden, but very few backyard gardeners actually think about propagating them themselves. Are you up for the challenge? If you want to take your onion game to the next level, there are two main ways to go about it.
Propagating Onions: Option 1
You can find onion seeds or sets (those tiny starter bulbs) at just about any garden center. Because they’re so readily available, growing onions is usually a breeze even for beginners. However, propagating your own is a bit more of a project. Even then, there are levels to it: one way is a bit more straightforward, while the other requires some serious patience and a bit of “green thumb” expertise.
The first option is to use store-bought seeds. You’ll grow these into your own sets (mini bulbs) during the first season. Then, you replant those sets the following spring. If all goes well, by autumn, you’ll be harvesting big, flavorful onions that you started from scratch.
Propagating Onions: Option 2
The second method is for the truly patient gardener. Here, we’re going back to the absolute basics by harvesting your own seeds from your own plants. You’ll sow these seeds to grow sets, which eventually turn into full-sized onions by the third year. Yes, you read that right—it’s a three-year process! It’s definitely a “slow gardening” project, but there’s something incredibly rewarding about watching the entire life cycle from start to finish.
Harvesting the Seeds
First things first: you need to get those seeds. Usually, we try to prevent onions from bolting (flowering) because it takes energy away from the bulb. But for this project, you actually want those flowers! Once the bloom fades, it will form a seed pod. That’s where your future onions are hiding. Fun fact: onion seeds usually stay viable for about three years.
Here’s how to harvest them like a pro:
- Harvest your onions in the fall.
- You need the flower head to dry out completely.
- To do this, hang the onion upside down.
- Pro tip: Tie a paper bag around the flower head so you don’t lose any seeds as they fall out.
- Let the seed pods overwinter in a cool, dark spot.
- In the spring, remove the seeds from the pods and you’re ready to plant.
- Want to be sure they’ll grow? Drop them in a glass of water to test their germination ability (the “sinkers” are usually the good ones!).
Harvesting Your Onion Sets
When you’re ready to plant your seeds, sow them very close together. The goal here isn’t big onions yet; we want to grow “sets” that are about the size of a hazelnut. Once they reach that size, pull them up and let them dry out thoroughly. Store them in a cool, dark place for the winter. About four weeks before you’re ready to plant them in the garden, move them to a warm spot (around 75-85°F). Congratulations! You’re officially ready to grow a crop of onions that are 100% your own creation.
