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How to Grow Onions in Containers: Expert Tips and Techniques

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Growing onions in containers can be a rewarding and easy growing experience. This blog post will cover all the ins and outs of growing onions in containers, including sunlight requirements, soil requirements, how long it takes to grow an onion harvest from pots, and the best onion types that thrive in small spaces.

I’ve grown onions in tiny containers on my windowsill with much glee. It’s so much fun to try your hand at container gardening, and you never know what you’re going to be able to grow!

Fresh onion in basket on wooden table, top view

Can you grow healthy onions in pots?

You bet you can!

Onions are one of the most versatile vegetables to grow in containers. They can be grown indoors and outdoors; they require little growing space because their roots don’t spread too far for nutrients. They produce well with less attention than other plants, and you’ll likely get a better yield per square foot when growing them in pots instead of growing them in the ground.

People are often surprised at how well vegetables like carrots, pumpkins, potatoes, greens, herbs, etc., grow well in containers, but they do! You can create a full robust garden without having access to land. You can even grow small fruit bushes like blueberries and raspberries in containers too. So don’t let space limit your ability to grow your own food.

grow onions on the window in pots. Sprouting onions on the windowsill.

What are some advantages of growing onions in pots?

There are many advantages to growing onions in containers:

  • You can control how much sunlight the onions get. If they’re growing in a container and you don’t want them to grow as quickly, place the pot in an area with shade to slow down the process.
  • Harvesting from containers could not be easier. There is no need to dig around in a muddy garden, get dirty, pull out the tools, or move around the soil. Your onions will pluck easily out of your containers, making harvesting quick and clean.
  • The abilty to grow onions in containers means it’s a viable option for even those with limited land or space.

Growing onions in containers on a window sill.

What are some disadvantages of growing onions in pots?

  • One disadvantage is that growing onions in containers might not produce large onions because they don’t have enough space to grow.
  • Keep an eye out on watering the containers – if you don’t water them enough, they can get too hot and become susceptible to mold.
  • Containers can also dry out very quickly in the summer heat, which will stress your onion plants. Stressed plants are more susceptible to pests and diseases.

How to plant onions in the container garden

Start onion seeds indoors at least 8 weeks before planting. Or buy onion starts from the nursery.

Plant them one inch deep and at least two inches apart in a container with drainage holes in the bottom.

Add soil around roots as they grow. When onion tops are about six inches high, add the more growing mix to cover growing tips of onions slightly above ground level if needed.

Growing onions in small containers in front of a sunny window.

What size pot do I need for my onion plants?

Container size is important for growing onions. A pot with a depth of at least six inches and width in proportion to the height will work well. The onion tops should not touch each other when growing but be separated by two inches or more.

Onion plants can grow as tall as three feet; choose wide enough containers to accommodate the growing plant.

Growing onions in a plastic tub in front of a sunny window.

What kind of soil should I use for growing my onion?

Soil requirements are the next key to growing onions – with the right soil, your container-grown onions will thrive.

Sandy loam is the best type of soil for growing your onion. It should have a lot of organic material and not be too heavy with clay or sand.

To create sandy loam soil at home, add a generous amount of compost, peat moss, and sand to your potting soil.

How much sunlight do container-grown onions require?

To get a good harvest of onions, they need at least six hours of sun per day. You can grow them in a shady area, but be sure they get at least four hours of the afternoon sun.

Note: Onions grown in the shade may not grow as large.

How much water do onions require?

Onions growing in containers need to be watered every other day.

To help prevent soil from becoming compacted, you can either place mulch around the base of your pot or add a few river stones to the bottom of the pot to help assist with drainage.

Note: If you are growing your onions outdoors in containers be sure to check on them daily on very hot days. Containers can dry out very quickly. You may need to water your containers daily during extreme heat.

What are some good varieties of onions for growing in pots?

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Many different types of onion cultivars do well when growing them in a container, but the most popular one is Red Creole. This type of onion has been specifically bred to grow well in container-style gardens.

Other cultivars that do well in containers are Golden Creole, The Walla Walla Sweet Onion (so good!), and Sweet Spanish White.

If you want to grow a different type of onion, make sure it has the words “container-grown” on the plant’s label when purchasing them at your local nursery or garden store.

Different varieties of container grown onions on a rustic tabletop.

How long do onions take to grow in containers?

The growing time for onions in containers can vary depending on the variety and growing conditions.

Onions grow fastest from spring through early summer, so you’ll want to make sure your container has plenty of sunlight during this period.

Most onions take 90-120 days to grow from bulb to harvest.

You can also harvest the green onion shoots during the growing season. Be sure to leave at least 4 inches of green growth on your onions plants.

How long does it take before onions are ready to be harvested?

The growing time for onions varies from cultivar to cultivar, but it typically takes about four to six months before you can harvest your onion crop!

How to harvest your container-grown onion crop

You will know your onions are ready for harvest when the leaves turn yellow and fall over, but make sure to check them every other day.

Once you harvest your onions, let them dry in a ventilated place for a few days before storing them.

  • Learn More: For more information on how and when to harvest your onions, check out our full guide!

Healthy red onions from a summer garden.

How long can you store your harvested onions?

You can store your harvested onions for up to six months in a dark, cool environment.

Please keep them in an open container to prevent condensation from forming on the onions. Condensation will cause mold and rot.

It would be best to keep your harvested onions separate from other vegetables and fruits.

I hope this guide gives you the confidence to grow onions on your patio or container garden this summer!

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