Grow Onions in Pots – 7 Important Steps

If you want to grow onions in pots, you must consider a few points! In my opinion, growing onions in pots is the most effective method. They are far simpler to handle than planting them outside in the ground and much easier to regulate than weed-like plants. Additionally, they don’t take up a lot of room in your yard or garden and let you experiment with growing several different species simultaneously. Everything you need to know about starting to grow onions in pots, including how to choose the best pots and water them appropriately, will be covered in this article.

Start to Grow Onions in Pots

How to grow onions in pots? It’s advisable to start simple when using onions for the first time. All you actually need to get started is one container, one bulb, and one plant. Consider extending into extra pots or planting more bulbs once you’ve had your first crop if your space permits. After this short introduction you are ready to look at the steps to grow onions in pots.

Now let’s have a look at the steps we need to go through to grow onions in pots!

Steps to Grow Onions in Pots

  • First, choose the right pot
  • Check for drainage in your pots
  • Then prepare the right soil
  • Choose the right place to grow onions in pots
  • Continue with planting your onions
  • Water regularly
  • Finish with good care (Fertilizer)

What Type of Pot Should I Use?

Onion Companion Planting

What Type of Pot Should I Use?

The best start you can make to grow onions in pots is to select the right pot. For onions, a range of pot sizes are suitable. The number of onions you want in the pot should be taken into account while selecting the optimal pot size. Typically, for every medium or big bulb you plant, add 1 inch to its diameter. Put 20 tulip onions in a container with a 20-inch diameter, for instance. Small bulbs like hyacinths may contain almost twice as many. Use containers 8 to 12 inches high in a 20-inch pot to give the roots and bulbs room to expand.

Are Drainage Holes Important?

Let us continue to grow onions in pots with another important task. Test the holes in the bottom of your pot before planting your onions. You can use a toothpick to unclog them if they are clogged. To assist hold the soil in place and provide more drainage, if necessary, you may also use a tiny piece of pebbles or a coffee filter.

Which Soil Should I Use?

What can I do to soften hard soil

A pH level of 6.5 or above is preferred since onions do not grow well in soil that is too acidic. You can add wood ash or ground limestone to your soil if the pH is too low. Otherwise, as long as they are grown in nutrient-rich soil, onions should thrive. By utilizing potting soil, you can make sure the soil is enough1.

A common problem is that your soil can get hard. This is not a good sign for your plant. So, make sure to soften it! How to do that? Very easy! Just follow our simple instructions in the article below:

Where to Place my Onions?

Choosing the right spot is an essential task to grow onions in pots. During the winter or early spring, growing onions indoors on a bright south-facing windowsill is excellent. When the onions are ready to plant, however, you may move them outside in following with the last normal spring frost date in your area. Onion sets can also be planted now straight into garden beds, 4 to 6 inches apart, and planted half an inch deeper than when they were in pots.

Grow some red onions indoors on your countertop or windowsill to add extra color and taste to your culinary foods! They’ll be prepared in around nine months. In order to give a greater surface area from which to produce leaves and bulbs, choose an onion type for indoor cultivation that has a big diameter base. When choosing which onion kinds are most suited for indoor growth circumstances, take into account whether the bulbs should be white or red.

The place you choose to grow onions in pots can be very tactical. Have you ever heard of the method of companion planting? If not, you must check it out! In short, it is basically planting several plants (which enjoy the presence of each other) together in order to benefit from their cooperation. The results are faster growth and avoiding pests! One point you must consider is that there are also bad companion plants. So, be aware of what you are doing and be picky with your choice!

We have a huge list of over 90 companion plant articles! Also, for onions! Check it out:

How to Plant Onions in Pots?


It is time to sow the seeds after about four to six weeks, or when they are around ten cm tall. It should be between six and ten cm deep. How big the bulbs may grow will depend on the size of the pot. Gently tap the potafter adding the potting soil. Create a hole in the soil using your finger or an implement like a pencil, then carefully insert the bulb plant.

Do not cover the plant higher than the white area above the roots. Instead, keep it near the surface. The bulbs should be spaced apart at least three inches. Give bigger bulb varieties more room. Water the newly planted plants often. In order to grow effectively, onions often require two to three inches of water every week.

It might be challenging to transplant your bulbs, particularly if you planted them all in one pot. That is why having someone observe you do it is beneficial. Like that you can grow onions in pots in a better way.

If you just have a little amount of room, pick plants that are larger than the rest and have sturdy cotyledons. Even if you have a large garden and don’t have any preferences, you may focus your attention on the plants that have the highest possibility of thriving.

When to Water my Onions

tomato watering greenhouse

The most crucial steps for growing onions on a balcony are weeding, watering, and fertilizing. Always water plant boxes or pots thoroughly so that the water may get all the way down within the planters. However, they must have a drain in order to function. Because waterlogged bulbs cannot withstand it, too much water may drain from this area. 

The simplest method is to measure the soil’s dryness before watering. When the soil remains dry, even four centimeters below, it can be watered. This will be one of the most important things you can do to grow onions in pots.

How do I Fertilize my Plants?

There are numerous guidelines to follow while fertilizing. You only require nitrogen, such as horn meal, if you grow plants in big pots loaded with compost. This swiftly breaks down in the soil, releasing its beneficial components for the plants.

If new compost cannot be added to the potting soil to re-fertilize it, an organic fertilizer with nitrogen, potassium, and phosphate2 should be used. 

As you all already know buying fertilizer can be exhausting sometimes. Which is the best? What fits my plant best? These are questions that make our lives harder. For that reason, we have prepared an article about making organic fertilizers at home! It is really easy, just follow our guide:

  1. Soliman, A. I., Morad, M. M., Wasfy, K. I., & Moursy, M. A. M. (2020). Utilization of aquaculture drainage for enhancing onion crop yield under surface and subsurface drip irrigation systems. Agricultural Water Management239, 106244.
  2. Nelsen, C. E., & Safir, G. (1982). Increased drought tolerance of mycorrhizal onion plants caused by improved phosphorus nutrition. Planta154(5), 407-413.