Winter gardening project: windowsill onions

Wendy S. Delmater
By Wendy S. Delmater on Mon, Nov 30, 2015 - 9:00pm

Here's a project anyone with a windowsill can do. Detailed instructions are here, but basically if you want fresh green onion tops all winter for things like soups, salads and garnishes, you’ll need:

  1. Onion bulbs. It's best to get onion sets, small immature bulbs that are basically seed onions, because not only the green tops will grow but you'll have edible onion bulbs when you are done. (Note: it's hard to get anyone to deliver onion sets in the winter: Seed catalogs will often not mail them until the spring so check delivery dates!) We saved bulblets/sets from our Egyptian walking onions and potato onions so I will be using those. I suspect it would work with bunching onions--the ones you buy as green pencil onions in the supermarket,  but you'd have to start them elsewhere until they were big enough to keep soil from coming out the sides of your garden. In my experience seeds are harder to start in the winter on a sill.
  2. Tall Clear Round Plastic Bottle. Minimum 2-3 liter soda pop bottle, or a half-gallon-to full-gallon clear juice bottle You can probably score one for free at your town's recycling center.
  3. Scissors to cut off the top of the bottle and cut holes. I've tried cutting holes in such a bottle and it's difficult so I think I will use something hot to melt holes in the plastic for that part.
  4. Potting Soil or compost. Let's face it, potting soil is expensive and if you have compost out in the yard you might as well use that.

Make sure your plastic bottle is clean. Then remove the neck and start to cut or melt holes the whole way around; the openings should fit the onion bulbs you will be planting without letting out any soil. Leave extra room if you are starting with immature onions for the bulbs to get bigger. Lay soil, then your onion bulbs in a circular pattern, repeating layers until you reach the top.

Replace the top of the bottle in place and water your windowsill garden. You'll want to place it by a window that gets a lot of sunlight during the day; a south or east window is best. Your onion tops will start growing within a few days. Plants lean toward the sun (it's called phototropism) so you'll want to turn your onion tower every so often so that the green shoots get even light and stay as straight as possible. Keep the onions from touching the cold windowpane glass especially if it freezes outside.


David Huang's picture
David Huang
Status: Bronze Member (Offline)
Joined: Jan 20 2010
Posts: 77

Thanks for the idea, Wendy.  I may give this a try with some of the tiny bulbs I pulled from the garden this year.  They are basically onion sets.  :)

Luke Moffat's picture
Luke Moffat
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Joined: Jan 25 2014
Posts: 384
Made me smile

Thanks Wendy, the ingenuity made me smile. There are no limits when it comes to practical thinking! :)

Uncletommy's picture
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Joined: May 3 2014
Posts: 633
variation of a theme

Great Idea. I tried that with strawberry plants in an old 20 litre water jug that had a crack in the bottom. Easy to water outside - might be a problem inside. Produced great strawberries, after I pruned them, hard in the early spring.

What did you use to contain the moisture and what kind of soil mix did you use?  High proportion of peat or cellulose? Worm castings? I've got a bunch of onion sets left from my seeded bed. How often do you harvest? 

Wendy S. Delmater's picture
Wendy S. Delmater
Status: Diamond Member (Offline)
Joined: Dec 13 2009
Posts: 1988
just started


We are using compost from one of our piles. I will let you know how they do - the pictures are of someone else's onion windowsill planting.

They did it for the green onions. I thought that was wasteful. I wanted to grow the bulbs, too.

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