Growing Onions indoors – 6 Ways to Grow Onions in Containers

This article shows you how to use onions as indoor plants. Growing onions indoors is a fun project and one that the kids will love to help with.Onions are easy to grow outdoors as well as inside the home.  They are one of those vegetables that we use often and the demand for this means that they are a great vegetable to grow.

Many gardeners think that they would love to grow onions, but they also assume that one needs a large amount of space to grow them. This is not necessarily the case and there is an easy answer to this problem. 

Just try your hand at growing onions in containers. Doing this will allow you to have onions growing on a small patio or deck garden, or even have them growing inside your home.

There are many types of this versatile vegetable. Find out about the onion varieties here.

If you don’t have the space for a  full scale vegetable garden outside, you can still grow onions indoors.

You can even have an endless supply of them if you do it just right since onions are a cut and come again vegetable.  (they will regrow from the original stock with roots.)

Onions are a very persistent vegetable. They will sprout, regrow, and sprout again. Just look at this basket of them. Many have already sprouted and could be used to make new plants.

Growing onions indoors gives you an endless supply when you need them.

There are lots of ways to grow onions outdoors, but they usually require a big garden space. Outside, onion sets are often used,(basically small undeveloped onions) but when we are thinking about the task of growing this useful vegetable inside, we have to think outside the box.

Most of these ideas will end up giving you onion tops, rather than onion bottoms, since those require quite a bit of space to grow.

But the sprouts of onion have a lovely taste, too, and can be used in all sorts of recipes, in addition to using them as garnishes.

For today’s project we will focus on the ways to grow them in a more confined area. Here are a few of the ways to grow onions indoors.  Kids will love these projects too!

Growing onions in containers

Growing onions in pots is easy.  You won’t get a large crop like you do outside, but the top will give you a part of the plant that you can use in recipes. Place a small whole onion in potting soil in a pot and it will spout new growth.  

You can either slice off the onion where the roots are, or place a small whole onion on soil and it will grow, in time. When it has developed repeat the process as often as you like. 

Growing onions in water

Onions don’t even need soil to grow. Growing onions in water is a project the kids will love because they can see the roots growing through the sides of the glass.

If you place a sprouted onion with the roots down in a glass of water, it will continue to grow on the top with new shoots. 

You can either cut off the top part and use it in recipes, or plant the whole onion, roots and all, in soil and watch it grow.

Onions can be a decorative plant too, as this photo shows. The onions are sitting in a bowl of water lined with pebbles. I also force paperwhites using the same technique with great success.

All types of onions will regrow.  One of my latest experiments was to try to grow vidalia onions from bottoms that would normally end up in the trash or compost pile. My onion sprouted quickly and gave off new growth in just a few days.

Feeling cooped up and need a project to keep you busy? Try growing onions indoors. Check out the tips on The Gardening Cook. 🧅🧅🧅 Share on X

Growing onions from onions

Don’t discard those old onion bottoms in the trash.  You can create an endless supply of green onion tops without ever having to buy more. This can be done with all types of onions.

The roots of onions are very persistent.  In this photo whole onion bottoms are planted in soil and the green sprouts are growing.  If you cut off the green parts to use in salads, more will grow.

Cut and come again onions

Growing green onions indoors is a cinch! This is one of my favorite ways to grow onions.  I buy one clump of spring onions at the store. Then I place them in a jar of water and cut just the green tops for recipes. 

You will have new growth before you know it and never have to buy spring onions again.  See my tips to re-grow spring onions in water here.

Growing Onions Vertically in Soda Bottles

This idea is such a fun one for kids to do.  Grow onions vertically on a window sill.  You will need a 5 liter bottle that you have made holes in.

Fill the bottle with potting soil and onion sprouts and watch your harvest grow indoors! The kids will be fascinated growing onions when they see the soda bottle covered with onion tips that have grown out of the holes in the bottle.

Growing Onions from Seed

Spring onions don’t take up much room outside and will send up flowers quite easily. I had one batch that took up just a square foot of space and it lasted about 4 years before it finally gave up the ghost.

Onions are biennials and will produce seed in their second year.

The plant sends up stalks with flower heads on them. These are called umbrels. When they go brown, cut them off the plant and place them in a paper bag and allow them to dry completely for a few weeks.

Once dry, give the bag a shake to separate the seeds from the other matter in the flower head and store them in a cool, dry place.

The seeds can be used to plant in soil both indoor and out and spring onions grow very easily indoors from these seeds. (Store bought seeds work too.) 

Grow lights are a big help for starting seeds indoors.

Planting sprouted onions

Onions sprout easily and that is good for getting more plants for free.  This project can be done on a deck. 

Get a 4 gallon container and add some wood chips about half way up.  Fill the rest of the pot with potting soil. (the wood chips will act as drainage.)  

Keep the soil evenly moist and the sprouted onions will grow for you.  The roots on the bottom will love the new, rich soil!

Do you ever reach into the onion bin and find an onion that has sprouted where the sprout actually splits the onion?  Don’t just use part of it and discard.  Put that sprouted part to work. 

Slice into the onion to expose the sprout and carefully cut the onion in two (take care not to disturb the sprout).  

Carefully cut around the sprout and plant.  You can use the part not planted but will end up with another onion too! 

Growing onions from sets

If you are interested in growing real onions and not just their tops, buy onion sets.  These are small, dry onion bulbs that have been grown the previous year. They are very easy gardeners to grow. 

Just press the small onions into the soil up to their tops, barely covered with soil 3-4 inches apart in rows. Since whole onions require room to grow, you won’t be able to grow many unless you have a really large pot.

Sunlight is also an issue.  Onions need a LOT of sunlight, so a south facing window is best. Normally, whole onions are grown outdoors or in pots on a patio.

The tops will be ready in 20- 30 days.  Whole onions take 100 to 175 days to reach maturity.  

Admin note: This post first appeared on my blog in January of 2017. I have updated the post to add more information and photos and also added a few new ways to grow onions indoors. I’ have also included a printable project card and a video for you to enjoy.

Would you like a reminder of this post for ways to grow onions indoors? Just pin this image to one of your gardening boards on Pinterest.

Have you discovered other ways for growing onions indoors?  Please share your tips in the comment section below.

Yield: Regrow onions from parts of whole onions, from their roots or from pieces.

Growing Onions indoors - 6 Ways to Grow Onions in Containers

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Growing onions indoors is a fun project to get the kids involved in gardening

Active Time 30 minutes

Total Time 30 minutes

Difficulty easy

Estimated Cost less than $1

Materials

• Sprouted whole onions
• Onion bottoms
• Seeds from onions that have flowered
• Spring onions
• Shallots]
• onion sets

Tools

• Water
• Soil
• Rocks
• Plastic bottle and sharp knife

Instructions

1. Place whole spring onions in a glass of water. They will sprout. Cut off the green tops and more will grow.
2. Place a whole sprouted onion in a soil. You'll get sprouted tops for salads that will regrow.
3. Cut wholes in a soda bottle. Add soil and place shallots in the whole area. They will sprout green tips.
4. Place a whole onion in a glass of water. It will sprout and grow leafy tops
5. Place seed onions in large pots of soil, they will grow whole onions.
6. Place large scallions in a bowl of water over pebbles. They will continue growing leafy tops.
7. Plant onion sets in soil. You'll get tops in about 30 days and whole onions in 3-6 months.
8. Collect onion seeds and use them to grow onions. (spring onions are best for doing this indoors)

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