How to Grow Awesome Onions


How to Grow Great Onions

There are a lot of benefits to growing onions in your garden. They don’t take up much room, so you can grow a large amount in a small area. They’re a short season vegetable, so you can often plant another crop in the same bed after your harvest the onions. And if you grow the right kind, you can store them in your house and eat them all winter long.

I love growing onions so much that I plant between 300-500 each year. They’re one of my favorite vegetables to grow in my garden.  And I store them in my basement and use them in cooking all throughout the winter and next spring.

They’re not difficult to grow, but there are a few keys things you need to know in order to have a successful crop.

onions growing in garden


Plant Early

Onions are sensitive to the amount of light in the day. The size of the bulb you’ll harvest later in the summer is related to how big the plant is when it starts bulbing. In the north the plants start bulbing up when the day length is around 14 hours. So, if you plant too late, the onions won’t have time to grow enough green leaves to encourage large bulbs. In Madison I plant my onions during the last two weeks in April.

Use Transplants or Sets, Not Onion Seeds

Don’t plant onion seeds directly into the ground in spring. They won’t have time to turn into bulbs. If you didn’t start onion seeds at home you’ll need to buy onion transplants or sets.  Transplants are seeds that were started a few months ago inside a greenhouse. Sets are immature bulbs that were grown last year.

Choose transplants if you have the option. The sets are more likely to bolt, or put up a flower, since they were started the previous year. I’ve gotten the best results by growing my own onions plants, so consider putting them on your seed starting list for this year if there’s time.

Growing OnionsMy husband prepping the onion bed in our community garden plot.

Choosing Varieties

There are three colors of onions – red, white and yellow – and two common types – storage and sweet onions. Sweet onions don’t last as long as storage onions. The drawback of buying sets is that it’s difficult to find storage varieties.

If you want to grow some onions for storage, try to find transplants at your local farmers market. I usually grow one variety of sweet onions to use for making salsa and fresh eating. The majority of what I grow are storage onions to keep in my basement and eat all winter. My favorites are Ailsa Craig, Pontiac, Redwing and Ruby Ring.

Prepping Your Garden Beds

In general I don’t spend a lot of time prepping my garden beds before planting spring vegetables. But, onions are the exception. Loosening the top few inches of soil before planting onions makes the task much easier. We use a digging fork and rake for the job.

Tight Spacing

Use six inch spacing and you’ll fit a lot of onions into your garden bed! We use a handmade dibbler that has prongs spaced six inches apart. It creates our holes for us so all we have to do is place the transplant into the hole and cover it with soil.

Planting OnionsUsing our dibbler for planting onions.

Weeding & Watering is Critical

The two practices most important to successfully growing onions are weeding and watering. Onions don’t compete well with weeds. It’s best to get them mulched as soon after planting as possible. It’s difficult to mulch small transplants with hay, so I wait a couple weeks until they get bigger.

Onions love water, so you must make sure they get one inch of water per week. I keep track of the weekly rainfall with my rain gauge. If we don’t receive one inch of rain during a particular week I water my onions very deeply.

Mulching Onions

Mulch your onions with hay to keep down the weeds and trap in moisture.

If you’ve had less success than you’d like growing onions, follow these tips and I bet you’ll have a completely different experience this  year.

If you want to delve more deeply into growing onions successfully, check out my eBook on the topic here.




Want to read more about growing tricky vegetables?

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  • I know you say that you place your onion plants 6 inches apart, but your dibble looks to have points 4 inches apart as I figure out by placing my hand on a ruler like yours on the dibble. Do you place onions 4 inches apart in rows that are 6 inches apart? …or is your hand just much larger than mine?
    I like the dibble and want to make one, just brought up short by this inconsistency.

  • I’m just starting to garden, so I apologize if my questions seem silly. Are transplants just seeds you started in a sunny window in Feb? And, are green onions just ones that are harvested before the form a bulb?

  • Hi Brianna- Yes, transplants are seeds either your or a farmer started in the winter. I don’t recommend growing your seedlings in front of a window because they need overhead light. If you want to grow green onions you’ll get the best results by buying seed meant for this purpose.

  • Hi Megan, I was wondering what type of hay you use for mulching? Thanks for your great blog!

    • Hi Penny – Thanks for reading! I use marsh hay. Be careful of your source. Make sure you’re not buying from someone who hayed a weedy field. Oat straw will work well most of the time, too. The oats may sprout but they usually die pretty quickly.

  • Hi, I would like to know how to tell my onions are ready to harvest and do you ever grow garlic in the same soils as your onions or with your onions I should say? I live in Mississippi so of course we have a warmer climate and a lot of spring rain. Thank you..

    • Hi Tamara- Your onions are ready to harvest when the greens flop over. I wait until this happens to the entire bed. I grow garlic in a different bed since I plant it in the fall. I don’t plant my onions until April.

      • What do you mean exactly “harvest when the greens flop over”? The whole plant? So what about when the flower bud stem curls?

        • Daphne- You shouldn’t have any flowers on first year onions. If you do, it’s probably because you’ve planted onion sets. They’re technically second year onions, so they sometimes go to flower. I’ve had the best luck growing my own onions from seed. When I do that I don’t get any flowers and all of the green leaves flop over when it’s time to harvest.

  • […] that peaked my interest. As I said above, Redwing is one of my favorite onions to grow. So, how could I resist a new and improved version? Answer: I couldn’t. I quickly added Red […]

  • nancy daniels

    How do you store your onions after harvest?

  • How long are your dibbler stakes?

  • Hi! I’m new to most gardening (especially veggies!) I was wondering how do you keep or store your onions since you grow so many? Thanks for your posts!!

  • I have started my seeds in 3″ peat pots. Will I need to remove them from the pots and put them in bigger pots? They are broccoli, cabbage and cauliflower for now. Tomatoes and peppers plus squash later. Zone five and I started them on February 22, 17. Thank you for your reply.

    • Hi John- It depends on what quality soil you used. If you see them starting to turn yellow you might need to replace the soil, although you don’t necessarily need to give them more room. I grow my brassicas in 4 packs or 6 packs, which are pretty small container sizes.

  • Sylvia Buck

    Dear Megan,

    I wonder if dried bracken could be used to mulsh onions in place of marsh or oat straw?


    • Hi Sylvia- I don’t see why not. Plenty of people use dried leave for mulching. Try it out and let me know how it goes!

  • How big are the prongs on your dribbler, ( width ) and how deep do you plant your onions. Thanks !!

    • Width is about half an inch. I plant my onions a few inches deep. I like to get them down into the soil and make sure all of the white and some of the green is covered up. It’s fine to plant them deep.

  • Schere Allen

    I have trouble getting large onions. Most are medium to small. A few will be large. What would be keeping me from getting large onions.

    • Schere- Are you using your own plants or buying from a nursery? Keeping them weeded and watered are two big things you can do. I also have better luck with growing my own seeds at home or buying transplants.

      • Do I have to worry about root maggots and if yes how do I deal with not getting them. I read wood ash works??

  • Thanks for your information on fall gardening and onions I found it very helpful!

  • I did something different with my onions this year. I used onion sets as opposed to seeds. What a big mistake. My onions were a disaster this year. I know a lot of people love starting from sets, but for me I’ll stick with the seeds. I do far better.

    • Mike- I agree! I’ve used both and I get much better onions when starting my own seeds. Not all experiments turn out well in the garden, but we always learn something from them!

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