Step-by-Step Guide On Growing Onions from Onions

I’ve been growing onions for years, and one of my favorite tricks is regrowing them from onions I already have. It’s one of the easiest gardening projects out there, perfect for beginners and seasoned gardeners alike.

Whether you have an onion sprouting in your kitchen or want to make the most of your grocery store produce, this method works like a charm. With just a little effort, you can turn a single onion into a continuous supply.

Choosing the Right Onion

Not all onions will regrow successfully, so it’s important to start with the right kind. I always look for firm, healthy onions with no signs of rot. If the onion has already sprouted, even better that means it’s eager to grow!

You can use almost any type of onion: yellow, red, white, or even shallots. However, organic onions tend to work best because many store-bought onions are treated with chemicals that inhibit sprouting.

If you’re serious about regrowing onions, it’s worth investing in untreated or organic ones.

Preparing the Onion for Planting

Once I’ve picked out my onion, I decide which method to use. There are two main ways to regrow onions: from the bottom root end or by separating the layers of a sprouted onion.

If I’m using a whole onion, I cut off about an inch from the root end and let it dry for a few hours. This helps prevent rot once it’s planted.

If my onion has already started sprouting, I carefully peel away the outer layers to reveal the green shoots inside. Each sprout has the potential to grow into a new onion, so I separate them gently, making sure each section has some roots attached.

Rooting the Onion in Water (Optional)

Sometimes, if I want to speed things up, I place the onion root-side down in a shallow dish of water before planting. This helps encourage root growth before transferring it to soil.

To do this, I fill a small bowl with about an inch of water and place the onion bottom in it. I change the water every day to keep it fresh. Within a few days, tiny white roots start forming. Once they’re about half an inch long, I know it’s time to plant.

Planting the Onion in Soil

I’ve found that onions grow best in loose, well-draining soil. They don’t like sitting in water, so I mix potting soil with a bit of sand or compost to improve drainage.

If I’m growing onions indoors, I use a deep pot with drainage holes to prevent soggy roots. For outdoor planting, I choose a sunny spot in my garden and loosen the soil before planting.

I plant the onion root-side down, covering it with about an inch of soil. If I’m planting sprouted sections, I space them a few inches apart to give them room to grow.

Once planted, I water the soil gently, keeping it moist but not soaked. Onions need consistent moisture to grow, but overwatering can cause rot.

Caring for Growing Onions

Onions are pretty low-maintenance, which is one of the reasons I love growing them. As they grow, I keep a few things in mind:

• Sunlight: Onions love sunlight. I make sure they get at least 6–8 hours of direct sun daily. If I’m growing them indoors, I place the pot near a bright window or use a grow light.
• Watering: I water my onions about twice a week, or whenever the top inch of soil feels dry. If the weather is particularly hot, I water more often.
• Feeding: Every few weeks, I add a little compost or a balanced fertilizer to give them a nutrient boost. This helps produce larger, healthier onions.
• Thinning: If the onion sprouts were planted close together, I thin them out once they’re a few inches tall. This gives the remaining plants more space to grow.

Harvesting and Regrowing Again

The best part about growing onions this way is that the cycle never has to end. After a few weeks, the green tops will be tall enough to snip and use in cooking, kind of like green onions.

If I want full-sized onions, I let them grow for a few months until the tops start turning yellow and drooping. That’s my sign that they’re ready to harvest.