Windows Sill Onion Tower
Isn’t this picture amazing? An onion tower. How cool is that? The question in my mind when I first saw this was… are they growing onion bulbs or greens? You see, it takes a lot of sun energy over many days to produce a full fledged onion like you would chop up to add to stew, chili or spaghetti sauce, and one shot of this onion tower shows full snow cover outside. You know what that means? Short, cloudy days.

Out of curiosity I tracked down the original post these images were from and discovered that the purpose is definitely a steady supply of onion greens. However, along the way I learned a lot more about onions that you’ll probably find both interesting and useful.

Onions that sprout can be planted.

What happens next depends on temperature and light. Also, you can’t just plant the whole onion. You need to carefully dissect the onion to keep the new growth in the heart intact, uninjured, and still attached to the root section. Any new fleshy roots forming between the outer layers of the bulb also need to be left intact. Remove any rotted or moldy parts from around the sprouts.

Most people declare that you cannot grow a fresh onion bulb from this green sprout section in the middle, and many think that part isn’t even edible! Amy at Anktangle is mystified as to why not, because she has successfully done just that and more than once.

Sprouting Onion Dissection
Her results could be due to a number of things, beginning with storage, and including when she pots them up. A lot of people store onions in their refrigerator, and these bulbs are highly sensitive to changes in temperature. In fact, Texas A&M says that the fastest way to make an onion bolt to flowering and seed production is exposure to vacillating temperature extremes. Onions aren’t stored in refrigeration before you buy them. Going from warm to cold to warm causes them to freak out and loose track of where they are in the life cycle. The blogger distinctly states that she stores them in the pantry, and growing them up is done outdoors – not inside.

Green onions aren’t a special variety.

They are immature onions. You can use the greens and pot up the white portions to grow into a bulb. The same is true of pearl onions . They aren’t any different than cooking onions – just harvested early. These too can be planted and grown on to large onions. Don’t worry about their roots being shriveled up or gone entirely. Stick them in soil or potting mix, give them some water, and they will soon start growing again. It’s not much different than planting ‘seed onions’ in the backyard garden in early summer.

All onions can be grown in containers. They don’t need tons of space or put down roots that go to China. Leeks do need depth, because they require hilling as they grow to produce that long white head. The rest of the onion family does not, and develops more above the soil than below it.

Can you grow onions indoors just with the light on a windowsill?

The green part, yes. As for mature onions, it depends on the type of onion as to how many hours of direct sunlight they need a day. There are short day and long day varieties that require either 10-12 or 14-16 hours of full sun a day. For that you need grow lights indoors, and you won’t know what kind of onions you’ve purchased from the store. Unless they are organic onions they have been treated to discourage new growth.

While onions, like potatoes, will sprout in the dark – they are looking for the sun. Without sufficient light energy, growing onion bulbs indoors is impossible. However, you can keep yourself in a steady supply of fresh onion greens year-around growing them in a sunny windowsill from seed onions, re-sprouted green onions and dried onions, or by potting up those pesky sprouting onions. If you’re growing new greens from the root portion of green onions – don’t leave them in water after new growth sprouts! They will rot. Onions like drier conditions with excellent drainage, and standing water is totally opposite.

Get the directions on planting your own windowsill onion tower here.

Sprouting onion image courtesy of Anktangle.com.

Amber

Contributing Writer at Garden Culture Magazine
The garden played a starring role from spring through fall in the house Amber was raised in. She has decades of experience growing plants from seeds and cuttings in the plot and pots.