How to Grow Green Onions in Water on Your Windowsill

The one thing I’m seeing on my Instagram feed as much as homemade sourdough bread? Green onion propagation. Chock it up to fewer trips to the grocery or a desire to nurture or just plain boredom, but it seems like everyone I know is growing their own green onions out of scraps. Naturally, my produce FOMO got the best of me and I had to try it out for myself. Here’s how to grow green onions from scraps in four easy steps, based on how I did it at home.

A Genius Trick for Saving Leftover Green Onions

how to grow green onions in water
Katherine Gillen

Step 1: I got a shipment of spring onions in a CSA box, so I sautéed them with Swiss chard and served them on top of polenta, saving the scraps for my experiment. (FYI, spring onions are a lot like green onions, but a little more flavorful and highly seasonal.) While prepping my dinner, I sliced off the very ends of the onion bulbs, leaving the root and some of the white stem intact. You can (and should) use the remaining white and green parts of your green onions to cook with!

Step 2: I placed the reserved bulbs in a glass cup, root-end down. You could also use a jar for this. I filled the jar with cold tap water: enough to cover the roots, but not so much that the bulbs were entirely submerged.

Step 3: I placed the cup o’ onions on my sunniest windowsill. According to my research (aka the internet and my gardening mom), the green onions will grow best in full sun—that is, at least six hours of direct sunlight on most days—but they’ll still survive with partial sun or some shade. Full disclosure, I live in a garden-level apartment with only east- and west-facing windows, so the amount of light my onions are getting is…not ideal.

Step 4: It’s grow time. (Heh.) After a few days, I noticed small green shoots sprouting from the tops of the bulbs. After consulting with a fellow onion-growing friend (“is it new growth or are the outsides shriveling up?”), I determined that I was dealing with new growth—wahoo! Your onions should grow at a steady pace like mine, as long as you give them enough light and refresh the water frequently. (I’ve found that every day is ideal, unlike the three to five days the internet suggests, or the bulbs will start to get mushy and slimy.)

how to grow green onions in water growth
Katherine Gillen

Step 5: The photo above is after about two weeks of growing. When the new growth is about five inches tall, you’re supposed to transfer the green onions to a pot filled with potting soil (or the ground). I know from previous plant propagation fails that this step is important—left in water forever, the plants won’t get enough nutrients and will eventually become too weak to grow. My next step? Hunting down some potting soil and transferring my new friends to their permanent home…that is, until I eat them again.

Despite seeing how easy it is to grow your own green scallions, you might be reading all this and still asking why? Fair enough. Aside from being a fun, time-consuming-but-not-tedious project, I see a few benefits to the scraps-to-scallions™ method, including:

  • Fewer trips to the grocery store
  • Less food waste
  • Less money spent on veggies that will see their untimely demise in your crisper
  • A chance to impress your friends with your newly found green thumb

FYI: The same growing method can be followed for many types of alliums: spring onions (like I used), leeks and ramps, to name a few. I’ve also heard it works for celery and romaine lettuce hearts, but I haven’t tried it myself—yet.


Senior Food Editor

Katherine Gillen is PureWow’s senior food editor. She’s a writer, recipe developer and food stylist with a degree in culinary arts and professional experience in New York City...