How to Grow a Store-Bought Onion

Simply Loren
Apr 17, 2023
3 min read

SimplyByLoren April, 2023

Image of Onions & Garlic beginning to sprout

Help, my onion started growing - is exactly what I googled yesterday when I saw my store-bought onion begin to sprout. I knew I wanted to start gardening this year, but honestly, if I hadn't seen my onion trying so hard to grow, I wouldn't have even bothered to pick up the shovel. Anyway, after deciding to help the little guy live, I did some research and was overwhelmed by the results. So, I decided to make things simple for everyone, and just give you an all-in-one, easy, step-by-step, guide on how to grow a sprouting onion:

Sprouting Onion Image from wikiHow — Photo from wikiHow

Step 1: Take off the excess onion skin

If you have a whole onion that has begun to sprout, or if you have a previously cut onion that is sprouting, you just need to extract the sprouting part from the rest of the onion pieces. Usually, the sprout will grow at the center of the onion bulb, so you can just cut through to the sprouting area and get rid of (or cook with) the rest.

Step 2: What color are your onion roots?

Brown: If you are seeing dry brown roots, it is not yet time to plant your onion sprout. Instead, put the onion into a glass with some water in it and wait for some white sprouts to form.
White: If you are seeing white sprouts, you can plant your onion straight into your soil.

How long do I have to plant onion sprouts before they are bad?

Your onion sprouts will hang around for about 3 weeks before they start to give up on you. So, ideally, you want to plant them before then.

Image of canvas bag that you can use to plant your onion in — If you have one lying around, you can even plant your onion into an old canvas bag.

Step 3: Where do I plant onions?

In part this depends on you, you can plant onions directly into the dirt, into a grow bag, or into a pot. This is because onions don’t need to be buried very deep. You only need to plant them about 1 inch into the ground and about 4 inches apart from one another so the bulbs have space to grow. You can also add mulch or compost to your onion sprout as well.

Step 4: Where should I keep my onion plant?

You can plant your onion wherever, but it needs an ample amount of sun. Keep in mind your climate, and if you live in a cooler space maybe keep your plant indoors. If you want, you can start by keeping it inside and gradually try to move it outside, but if you just toss your onion in the cold without giving it time to adjust it might die.

Step 5: How do I water my onion sprout?

You can water onions every few days. Make sure to wet the soil and not the plant itself, and if you are using mulch you only need to give your onion an inch of water a week:

Length of your garden in inches x width of your garden in inches

Step 6: How to Maintain my onion sprout?

Other than watering, just keep out any weeds. You can also opt for a fungicidal spray if you would like. This will prevent fungi from destroying your sprout. You can just spray it a couple of times every week and you should be good.

Step 7: When will my onion be ready to harvest?

60-80 days. If you see the bulb emerging from the soil, if the sprouts wilt or turn brown, or if flower stalks appear, it is time to harvest. Ideally, your onion will be the size of a baseball by the time you pull it out of the ground.

Image of onion growing out of the ground ready for harvest

How do I safely pull my onion out of the ground?

Just pull it vertically up and then you can lay it in a cool dry place until they shed some skin and then you can remove the roots. Or you can just eat them, up to you.