How To Grow Green Onions Indoors In Water & Soil

Growing certain vegetables indoors from kitchen scraps has been an increasing trend over recent years. And, lots of people are doing it quite successfully. To that end, I want to explain how to grow green onions indoors both from scraps in water and also from seeds in soil.

While I haven’t wholeheartedly embraced the practice of growing from scraps, I have dabbled with it a little and know that it is possible. But, using this method means that you’ll only be able to use the green part of any plants that you intend to grow this way. 

Why haven’t I embraced this practice? Quite simply because where I live, I can grow a variety of different vegetables outdoors in a garden bed for most of the year.

Plus, I have expert horticultural and garden knowledge and experience so I tend to use that when I want to grow a variety of different plants including vegetables such as green onions and even bulb onions.

But, I also understand that not everyone is as fortunate as me. Some people have to deal with extreme weather conditions so their outdoor growing season is limited. On the other hand, others don’t have the convenience of an outdoor growing space so they have to resort to growing in small spaces and often indoors.

So, I want to help out by explaining the growing from scraps method that is quite popular as well as the more traditional method of growing in soil using seeds or seedlings. Both methods will work and both can be used indoors.

Growing Green Onions From Scraps In A Glass Of Water

Green onions, or spring onions (Allium fistulosum) as they’re called here in Australia, are amazingly easy to grow. Other popular names for these are scallions or bunching onions. Once planted, they require minimal care. All they really need is enough water for sustained growth if the weather has been dry.

As a bonus, they don’t take up a lot of space and have a fairly shallow root system so I tend to scatter them around my other vegetables in the garden. The other bonus is that they grow rather quickly and are usually ready to harvest in under 2 months if you start them as seedlings in the garden.

But, you can also grow these versatile vegetables from a bunch of green onions purchased from a grocery store that still has the roots attached. All you have to do is cut off the bottom of the thin white bulbs, making sure that the roots remain intact. You want to retain around an inch (2.5 cm) of the bulb.

What To Do

Find a small jar and put a small amount of water in the base so that the water will only cover the roots. I find shot glasses work well for this too. Then just place the root end in the water making sure that just the roots are submerged.

Now this is very important – make sure that the water only covers the roots and not any part of the stem or bulb. Why, you ask? Because if the actual stem is submerged in water, it will rot much like the root rot that you can get with succulents that have not been allowed to dry out in between watering.

Place the glass or jar of water in a sunny spot. A bright window sill is ideal. Make sure that you change the water at least every couple of days. Soon, you’ll see some new growth start to appear from the top of the stem section or bulb. This should only take a couple of days.

Plant Your Newly Shooted Plants In Soil

Now this is where it might get a little tricky. It’s difficult for the little plants to continue growing because there are no nutrients in the water to sustain them.

While some people suggest that you should now plant them in soil, this doesn’t always work either. I’ve tried this with some bok choi that I grew from scraps and the plants just died.

On the other hand, I have seen some gardeners who have had success with doing this. So, it is worth giving it a try to see how you go.

The reason for this kind of hit-and-miss result is that the roots that grow in water are quite different to the roots that develop in soil. So, when the little plants are transplanted, they go into shock and might not recover.

But, you could continue to grow them in water if you added some nutrients and this is what I would suggest. Think of this as being similar to growing plants hydroponically. So, you’ll need to get some hydroponic nutrient solution and add a small amount to the water every time you change it.

Now, I haven’t tried this, but my knowledge of plants and how they grow would suggest that it should work.

You can find a range of hydroponic solutions from brands such as AeroGarden and TPS Plant Foods in small bottles that are fairly inexpensive.

This method should allow you to harvest the green tips and then allow them to regrow at least three to five times before the plant decides it’s time to develop a flower stalk and go to seed.

In fact, I’d like to experiment with this method myself, so keep your eye out for future articles, if and when I decide to give it a try.

Growing Green Onion Plants Indoors In Soil

in my opinion, this is the best way of growing green onions indoors and one that I know you’ll get the best results with. It involves growing your green onions in a pot filled with premium potting mix to resemble similar conditions to growing them in the garden.

For this method, you can either start with seeds or seedlings that you’ve purchased from your local 

nursery or garden centre.

Did I mention that green onions have fairly shallow roots? This means that you don’t have to have a deep pot for this to work. In fact, your pot only needs to be around 3 inches (7.5 cm) high to grow these plants. Of course, you can choose a deeper pot if you want but just make sure that it has good drainage.

Growing From Seed

To grow your green onions from scallion seeds, all you have to do is almost fill the pot with some premium potting mix. Then, scatter some green onion seeds across the surface and cover this lightly with a little more potting mix.

Give the mix some water and place the pot on or near a bright window sill. Keep the soil moist and the seeds should germinate fairly quickly and you’ll start to see some green shoots appear above the soil surface.

Once the green tops have reached a decent height, you can just snip them off instead of pulling up the entire plant. Just leave the base of the stem or bulb in the soil. This should continue to regrow and you can have continuous harvests of green leaves until the plant decides to go to seed.

This method of regrowing works because the roots of the plants are already growing in the soil and don’t need to be conditioned to it.

Using Green Onion Seedlings

You can use a similar method if you choose to start your plants from seedlings. So, instead of scattering the seeds on the potting mix, you just want to use a pencil or dibber to create some holes for the young plants.

Plant each seedling into a hole, using the pencil or dibber to gently guide the roots down into the potting mix. Firm the mix gently around each seedling and give the soil some water.

Place the pot on or near a sunny windowsill and continue to water the soil as it dries out. Your plants will continue to grow happily and you can snip off the tops as you need them.

For even more indoor growing ideas, check out my article on 10 vegetables you can grow indoors all year round. And, if you enjoy growing green onions, you might also want to know how to grow allium bulbs.

Frequently Asked Questions

Final Thoughts

Growing your own green onions indoors is as easy as it gets. Whether you choose to grow them from scraps in water or you use the more traditional method of growing them in soil from seeds or seedlings, you should have a continual harvest of green onion tops for many months. 

So, if you relish the thought of having a steady supply of green onions to add to your cooking, give these methods a try. You won’t be disappointed.