How to Grow Onions: The Complete Backyard Grower's Guide - Backyard Boss
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How to Grow Onions: The Complete Backyard Grower’s Guide

You will be crying tears of happiness once you learn how to grow onions. Well, maybe a few of those tears will be from cutting the onions you harvested, but either way, having an endless supply of onions in your backyard is awesome! Onions are a tasty and versatile food.

Is it hard to grow onions? Absolutely not! They are extremely hardy and can be grown in numerous different ways, successfully. This tutorial will teach you how to grow onions in your garden, indoors, in containers, from scraps, from full onions, and more, answering all of your onion-growing questions.

What You Will Need

  • Onion Set/Seeds
  • Soil
  • Water
  • Fertilizer
  • Straw (optional)
  • Mesh Bag (optional)
  • Common Gardening Tools

What is the Best Way to Grow Onions?

You can grow onions from seeds, sets, scraps, and sprouting onions.

Planting scraps and sprouting onions are extremely easy, however, they tend to only grow onion sprouts, so if you are looking for bulb onions this is not the way to go.

Onion seeds need to be grown inside and transplanted to your garden which requires more work. However, they normally grow larger onions than onion sets.

Onion sets are easy to grow because they can be planted in your garden directly. They are the most popular way to grow onions, and what most people would call the best way to grow onions. They are resilient against frost damage and have a higher success rate than onion seeds. When picking out your set keep in mind that bigger is not better. Onion sets that are bigger than a dime may bolt too quickly.

Planting Onion Seeds Indoors

If you are growing onions from seeds you will need to start your plants indoors. Start growing them in trays in a cool location at least 6 weeks before you want to move them outside. Keep them moist so they will germinate.

onions growing indoors in window box

Once they reach a height between 1-2 inches move them to deep biodegradable pots with loamy, fertilized soil. Plant them shallowly in the pots. They should be placed on a windowsill so they get sun or near fluorescent bulbs.

Eventually, when the soil outside becomes warm enough, you can start hardening them off outside. Once you finish the hardening process, you can plant them in your garden.

Growing Onions in a Container

Growing onions in a container is very similar to growing them in the ground. The only difference is that you do have to pick out an adequate container for holding them and you also have to water them more.

The container you plant your onions in needs to be BIG because you have to plant several onions if you want a decent yield. The container should be at least 10 inches deep and 3 feet wide because onions need to have 3 inches of soil around them to properly grow.

You need to water your onions more when you grow them in a container. In a container, they need 2-3 inches of water a week but can need more if you live in a hot place. To make sure you are watering them properly, check the soil around your onions every day. If it is dry, water them.

Make sure that you place your container in a spot that gets lots of sunlight, whether it is outside or next to a window indoors.

Growing onions in containers is extremely easy and is a great option for people who don’t have a garden or garden space, but love onions!

How to Grow Onions From Scraps

Next time you are about to throw your onion base away, don’t! Instead, use it to grow more onions. It will grow best if it still has about 1.5 inches of onion attached to it, or around ⅓ of the onion bulb. Dry the bulb until it starts to shrivel and curl near where you cut it. This will take at least a few hours, maybe a whole day.

cutting onions to plant in soil

Fill a pot with potting soil. Make an indent in the soil that is the size of your bulb’s base before putting the bulb in it, root side down. Press down, and then cover it so the top is not visible. Water evenly, keeping the soil moist. Eventually, green shoots that you can use for cooking will pierce the soil’s surface!

You can also grow onions from green onion cuttings, by sticking them in a small container with soil, giving them lots of water, and making sure that they get plenty of sunlight!

How to Grow Onions from an Onion

Oh no! You just discovered a rogue onion left in your vegetable dish for too long, forgotten and alone, that has sprouted. What is there to do? Well, you could give up and throw it away. Or, you could use it to grow onion sprouts!

It is super easy. Simply fill a container with potting soil. Dig out a hole in the middle of the soil that will perfectly fit your sprouted onion. Place the onion in that hole and cover it with soil. Place the pot in a sunny spot and water it regularly, monitoring it and waiting. Eventually, green sprouts will grow for you to harvest and add to dishes.

Bonus: If your onion sprouts a flower, wait until it goes to seed. Then collect the seeds and save them for planting onions in the spring.

How to Grow Onions: A General Guide

Step One: Prepare for Your Onions

Before anything else, you have to decide whether you are planting onion sets or seeds, and what kind of onion you are planting. Choose the type of onion based on where you live because different onions thrive in different places. You can choose between short-day region, intermediate-day region, or long-day region onions.

Onions are a cold-season crop so you can plant them earlier than your other produce, in early spring, once the temperature is at least 28 F on a regular basis. It is a widely held belief that the earlier you plant your onions the bigger they will be.

Onions should be planted in a spot with full-access to the sun for the majority of the day. Use loose, well-drained soil that has a high nitrogen content.

Pro Tip: You can plant onions in places with mild weather in late fall or the winter. They will not grow throughout the winter but will start to sprout once spring weather arrives.

Step Two: Plant Your Onions

Before planting your onions, add a nitrogen fertilizer like compost or manure to the soil. You can work the fertilizer into the soil as you dig a shallow trench for the onions.

The onions should be planted in the trench, about an inch below the soil with at least 4 inches between each onion. Onion sets should be planted with the pointed end facing up.

If you are transplanting onions, plant them right on the soil’s surface. Transplants should be in rows at least 12 inches apart. Within the rows, the transplants should be at least 4 inches apart.

Pro Tip: Add straw between your rows of onions. This will aid moisture retention and stifle weeds.

Step Three: Care for Your Onions

At this point, you may be feeling impatient for your delicious onions and wondering, how long does it take to grow onions? Onions take about 3.5 months to fully mature.

healthy onions growing outdoors in soil

While your onions mature, the area around them should be kept weed-free.

Each week add nitrogen-rich fertilizer to the onions. This will increase the size of the bulbs. As soon as the onions push through the soil, stop fertilizing.

It may be tempting to cover the onions with soil once they push it back but do not. They must emerge above it. They will start to swell in late spring and will continue to increase in size until the dead of summer.

Water your onions with one inch of water a week. The more you water, the sweeter the onions will taste. Take rain and drought into account when watering.

If onion maggots start to attack your crop cover it with a fine mesh netting to protect it.

Step Four: Harvest Your Onions

Immediately harvest the onions if the weather turns cool in late summer, because that can spoil them, or if they sprout a flower, because that means they are done growing.

Otherwise, wait for the onion tops to turn brown.

You can speed up this process by bending the onion tops down or stomping on them as soon as they turn yellow. You can also loosen the soil around them to help with the drying process.

Once the tops completely fade and then fall over, dig your onion bulbs out, loosening their roots. Cut back the tops to 1 inch, and clip the roots of the plant. Then, gently adjust the remaining leaves down, not breaking them off the bulb.

Leave the onions out in the sun for a few days so they can dry.

Pro Tip: Be extremely gentle with the onions. Even a small bruise can cause a whole onion to rot.

Step Five: Enjoy!

Once you have harvested and cleaned off your onions, you get to eat them!

The work of growing them is done, but the work of deciding what to use them for is just beginning; there are so many delicious onion recipes to choose from!

row of onions in backyard gardenIf you don’t want to eat all of your onions at once you can store them. Before storing, allow your onions to dry for several weeks. The best way to do this is to spread them out on an open screen off the ground.

Store them with their tops braided together, hanging, not piled on top of each other, in a mesh bag, in a place with temperatures between 40 F to 50 F.

Onions should not be stored with fruits because they will ruin each other’s flavors.

Pro Tip: Pungent onions store longer than sweet onions.


Onions are not only delicious, they are also extremely nutritious, boasting benefits like increasing circulation, lowering blood pressure, and preventing blood clots.

They are an incredibly easy to grow versatile vegetable that will make an excellent addition to your garden.

I hope you enjoyed this tutorial! What was your favorite method for growing onions? Do you have any questions about any of the techniques? Let me know in the comments, and as always, if you liked this article be sure to share it!