How To Grow Onions In Your Garden

Growing onions in your home garden is easy and rewarding. There's nothing quite as delicious as a large, sweet garden-grown onion.

Variety Of Onions
(Image credit: leventina)

Who doesn't love a big slice of onion on a sandwich or burger? Onions are a staple at my house, and homegrown onions are a welcome pleasure. Growing big juicy onions in your garden is such a satisfying project. They aren't hard to grow and it's worth learning how.

How Do Onions Grow?

Onions (Allium cepa) are part of the Allium family and are related to garlic and chives . How do onions grow?

Onions are fascinating. They grow in layers, which are essentially an extension of the leaves of the onion. So, the more leaves you see emerging from the top of the onion, the more layers of crunchy onion there are underneath. If you see lots of leaves, you can bet you're growing some big onions.

How to Grow Onions from Seeds

Growing onions from seed

Onions grown from seeds take longer than other methods. Especially if your area has a shorter growing season, you'll need to start by sowing onion seeds indoors and transplanting the seedlings later to the garden.

Sow onion seeds indoors 8 to 12 weeks before the last frost in your area. Place your seed pots in a warm indoor location with full sun or under a grow light and cover them with 1/2 inch (1 cm) of well-draining soil. Water as needed until it is time to transplant. You can soak the seeds overnight to give them a bit of a jump-start. When the seedlings have germinated after a couple weeks, plant them in late April or early May in fertile, well-draining soil, about 4 inches (10 cm) apart. Be sure to plant them where they'll receive full sun.

Onion sets from seeds

To grow onion sets from seeds, start the seeds in your garden in mid to late July and dig them up after the first hard frost. Allow them to air dry before you store the onion sets in a cool, dry place for the winter.

How to Grow Onions From Sets

Onion sets are onion seedlings started late in the onion planting season the year before and then stored over the winter.

When you buy onion sets, they should be about the size of a marble and feel firm when squeezed gently.

The onion planting season for sets starts when temperatures get to be around 50 degrees F (10 C).

Choose a location that gets at least six to seven hours of sun every day. If you want to grow large onions, plant the sets 2 inches (5 cm) in the ground and 4 inches (10 cm) apart. This will give the onions plenty of room to grow.

How to Grow Onions from Transplants

If you want to grow large onions, your best bet is to grow them from transplants. Transplanted onions grow larger and store longer than onions grown from sets.

Once the last frost date has passed, the onion planting season begins. Harden the seedlings off before moving them out into the garden, then transplant the onions to their beds.

Your planting location should be in full sun with well-draining soil. Push the seedlings just far enough into the soil to get them to stand up. Plant them 4 inches (10 cm) apart.

Watering them well is necessary for growing big onions. Onions need at least 1 inch (2.5 cm) of water every week until harvested.

Harvesting and Drying

Once you've pulled your onions from the ground, they need time to dry and cure. Put them in a clean dry location where there is good air flow for 2 to 3 weeks. When the necks and tops have thoroughly dried and the papery onion skin becomes a bit crackly, you can store them in a dark, dry cupboard, a box or if you plan to use them soon, in the fridge.

Try some thick-cut onion rings baked in the oven. Coat them with flour, egg and panko crumbs for a delicious treat.

Heather Rhoades
Founder of Gardening Know How

Heather Rhoades founded Gardening Know How in 2007. She holds degrees from Cleveland State University and Northern Kentucky University. She is an avid gardener with a passion for community, and is a recipient of the Master Gardeners of Ohio Lifetime Achievement Award.

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