How to Grow Onions in Pots [Ultimate Guide For Beginners]

This Article contains information on how to grow onions in pots. Under suitable conditions, onions are arguably one of the easiest plants to grow, but how does one grow onions in pots?

Post Summary:

1. Pick a pot that is at least 8 inches deep
2. Fill the bottom of the pot with soil, and create a hole in it for planting your onion
3. Add water to the soil until it is moist but not soaked
4. Plant your onion so that about 3-4 inches are sticking out from the top of the dirt
5. Put a cover over your pot to keep moisture in and to protect against frost damage
6. Keep an eye on how much water you need to add each day – if there’s too much or too little, adjust accordingly!


The first thing you need to know is how much space an onion requires. Onions are very adaptable when it comes to soil and water. They like fertile, loose soils with good drainage; they want the weather warm and sunny; and they prefer plenty of moisture, especially while the bulbs are sprouting. Once you’ve planned out the space and viable condition for your onions, the next step is preparing the pot for plants.

Rinse your pot with water and fill it about halfway with soil. Mix some compost or manure into your soil until it feels good to touch, not too hard, not too wet… just right!

In a larger container or in the ground you would more likely add fertilizer as well during this step. The quality of your soil and compost will have a huge impact on your plant growth so spend time getting this right.

Although the primary goal of learning how to grow onions in pots is to maximize your garden space, you should keep in mind that, Ideally, your onion pots should be kept in a sunny area that receives natural light throughout the day. If you don’t have direct access to natural light, an indoor location that is well lit with artificial lighting will suffice for growing onions indoors, it is always better to provide them with the most sunlight you can to support them during their growing cycle.

The depth of the pot can make a big difference in how well (or how badly) your onions do. The depth is important not only for how long it takes to get the onion growing, but how deep they’ll grow.

Once you’re done preparing the pots, the next step is planting your onion bulb.

Is an Onion A Vegetable?

Growing Onions In Pots: Planting Process

The way you plant your onion bulb will vary depending on how large it is, how many you intend to plant in a single pot and how long you want the onions to grow. If your onion has a good bunch of green shoots coming out of it already (called sprouts) then they are ready for transplanting. Growing onions from seedlings mean that at some point, they will have to be transplanted into their pots or garden beds.

For really small pots or those with tiny onions, plant the onion bulb in the center then plant 2-3 sprouts around it. For larger pots and bigger onions, plant multiple bulbs at different locations. Each pot should have one or two bulbs with 3-4 sprouts planted around each bulb. This is not a rule of thumb, but it’s a good way to get started with proper planting plans.

If your onions still lack any green shoots, they’ll need a few days to get growing. Don’t worry if your onions are not ready for planting right away. Please keep them in the sunny area you’ve been keeping them in and let them grow a little bit more before transplanting, depending on how much and how long you want the onions to grow, the period before transplanting can vary greatly.

Pack the soil around your onions as you make holes for them to be planted. Remember how deep you planted the bulbs, and how many times you turned them up vertically. Plant the bulbs at about half or 3/4 of that depth, or at a 6-8cm (2.5-3in) depth.

Here is a list of things you need to grow onions in pots:

– Clamshell container or pot (which you can use for planting and growing onions)

– Organic soil mix (3 parts peat moss, 2 parts composted manure/fertilizer blend, 1 part perlite; no synthetic fertilizers)

Vegetable fertilizer (granular)

– Hand trowel or small shovel

– Watering can/sprayer

– Onion bulbs for planting, separate from the ones you are going to eat. These onions could be a variety your want to grow for seed purposes, or they could be onion sets that you purchased at the garden center.

Now that we’ve covered the base on how to prepare the pot and how to plant the bulb properly. The next paragraph is focused on tips on how to grow onions in pots.

  • Pot Size: The size of your pot is important. The number that you should look for is how many gallons the pots are for sizing purposes. It’s usually most recommended to have up to one gallon for each onion bulb being planted in a container(growing onions). 3-5 gallons is considered an ideal size.
  • Soil Type: For a healthy onion plant, the type of soil is an important thing to look at when planting your onion in a pot. You should use well-draining soil. Most people use either a potting mix or a topsoil/compost-based product like Miracle-Gro Potting Mix.
  • Sunlight/Lighting: Depending on how big your pot is, how much light your onion plant will need needs to be figured out. If the container is small, with about 3 gallons or less in it, then an indoor location may work just fine. But if you’re using a larger plastic container like 5+ gallons, then either direct sunlight or an artificial source of light would be needed. If you end up using artificial light, the lights should be about 6 – 12 inches above the plants.
  • Watering: Another important thing besides light when it comes to growing onions in pots, is the frequency at which you water your onion pots. It is important that you don’t let them dry out which can lead to the destruction of your onion plants. If they get too dry and die, it’s not a big deal; you’ll need to buy new ones. But if you kill off all of your onions by drowning them in water, that wouldn’t be good either. So moderate is the key here.
  • Variety: Some types of onions grow well indoor as compared to others, so it is recommended that you buy different types of onions to grow in pots. You could try white onions, yellow onions, and red onions. They are all from the same family so they usually do better when planted close together. You can experiment with various types and decide as you understand the species more.

It is recommended to grow them on your window sill or any place with an adequate amount of sunlight.

Where to get Onion Bulb?

You can either buy the onion bulbs online or at your local superstore and plant them how you would usually plant other vegetables. If you have bought the bulbs be sure to include some fertile soil when planting them as this will help improve how well they grow and how big they can become over time.

However if you have not purchased the bulbs, don’t worry because using individual onion sets is also another great way to go about growing onions indoors. The sets will be able to grow on their own and you’ll only have to buy a few of them.

The soil should also remain fairly moist throughout the growing process, how much water each set gets will depend on how warm or how cold it is inside your house/room where they’re growing.

How do onions reproduce?

Onions reproduce themselves via seeds which can then be planted in fertile soil. They are more likely to spread this way than from growing new bulbs so make sure if you want them to multiply by doing this that they are grown somewhere away from your other plants as not all plants like having too many onions growing around them at once!

Conclusively, space, water, light and variety are some of the most important things to consider as you research how to grow onions in pots.