Next to garlic, onions are one of the easiest things to grow. Requiring little attention, they are a hardy plant that can and will do well in just about any environment. If you are a beginner gardener, learning how to grow bigger onions is a great way to get your feet wet in your backyard garden.
Another plus to growing onions is once harvested, they will last quite a while if stored correctly.
Whether you keep your onions stored in a cool dark root cellar, add them to canning recipes, or dice/slice and freeze, you can easily enjoy your summer harvest throughout the winter months.
With so many varieties and uses, onions are a staple in just about every home. No matter what you cook more often than not onions are likely to be an ingredient that is called for. And that is great news because onions are a very economical vegetable to grow and one to buy as well.
How To Grow Bigger Onions – a Step by Step Guide
Step #1. Prep Your soil
Not all soil is created equal. This was something I learned the hard way. Most soil needs to be prepped before it can be planted and I cannot stress enough how important this step is. Without healthy soil, most if not all, of what you plant will do poorly. By taking the time to ensure your soil is at its very best you will be already ahead of the gardening game.
Now, don’t let this step deter you from gardening. Being sure your soil is healthy and balanced is actually easier than you may think.
SLCG PRO TIP: Onions prefer Nitrogen-rich soil so keep this in mind when preparing to plant. You can purchase an inexpensive soil testing kit so you know just exactly what improvements your soil needs. If you test and find your soil is low on Nitrogen, you can improve things with a healthy dose of compost.
STEP #2. Choose the Best Onion Variety
With so many choices out there, it can be a bit overwhelming deciding exactly what onions you will want to plant. There are quite a few varieties, but the most common are:
- Scallions – Also known as spring onions. Scallions have a mild taste and can be used in recipes that are both raw or cooked. They also work well chopped up raw in summer salads.
- Vidalias – A lovely sweet onion that can be used in dishes, with a mixture of grilled veggies or even cooked and eaten alone. Since Vidalias are sweeter you may need to adjust your recipe a bit to counter this if needed.
- Yellow Onions – Are the most popular onion and probably what the average cook is used to having in their pantry. A light sweet flavor they work in just about any dish from sweet to savory. Yellow onions are the most commonly found year-round in the grocery store.
- White Onions – Have a more pungent flavor than yellow onions and work well in salsas.
- Red Onions – With flavors that closely resemble the yellow onion, these do best raw in salads.
- Shallots – Have a flavor that is softer than a yellow onion resembling garlic more than onion when you add it to dishes.
- Leeks – Have a more delicate flavor than that of a yellow onion and do very well in stocks and soups.
My best advice is to try a few and see what you like. I prefer the yellow onion simply because of its wide range of uses. These onions do very well in all styles of cooking and are perfect for soups like French Onion. Before you plant know what you normally cook to help you better narrow down your choice. Also, remember that the right variety depends on where you live and what grows best in your local environment.
Step #3. Onion Set, or Seed
Where I live sets work the best. Not sure what sets are? Read on for a description of each and what will work best for your area.
What is an onion set?
An onion set is a small bulb of onion that has been started from seed, grown, then stored to plant for the next growing season. They resemble a mini onion and are usually sold in mesh bags or brown lunch bags to help keep them fresh. Sets are a great option for northern gardens because they give you a bit of a growing head start that seeds do not.
Onion sets are easy to plant and require less attention than seeds. The cost is still pretty low with this option, about $2 a pound which will give you approximately 100 or more sets depending on the size.
If you prefer the less costly seed option be prepared to do extra weeding since the seedlings can easily be crowded out especially in the beginning when they are small and fragile.
You can also start your seeds indoors and transplant them when they are bigger. Seeds need to be started about 6 weeks prior to outside planting and hardened a few days to acclimate them to your weather.
Step #4. Plant at the Right Time
Here in Pennsylvania, I have found it is best to plant onions just as soon as you can work the ground. This for us is late March or early April.
Check your Gardening Zone to know the best time to get your plants into the ground.
If you miss your window to plant, don’t worry. You can still get those sets into the ground. Just know that harvest time will be well into the fall rather than late summer. Remember, the later you plant the later your harvest will be. Another thing to remember is the later you plant the smaller those onions are going to be.
Bottom line? Get your onion sets into the ground in the window your zone allows.
If you plant a large number of onions, it is best to stagger your plantings. What I mean by that is, plant 1/3 of your sets on week one, the next third on week three, and the final third on week 5. This way you will have a steady stream of ripe onions come fall. Again, be sure you have a large enough window to do this before deciding to stagger plant your onions.
Step #5. Plant in Raised Rows
Where we live, our entire property is wet. Really – really wet.
This means, if I am not careful, most root vegetables run the risk of rotting out rather than flourishing.
A few years ago I was given advice by a farmer friend of mine to put our onions up in heaped rows. This would allow the onions to sit above the resting water we are always battling here.
The following year I took his advice and the results were pretty amazing. Our onions were HUGE! And the level of rot was pretty much non-existent. I was so impressed with the results, that I now plant most of my root vegetables this way.
When making your rows use a garden hoe and work the ground line by line, pulling the dirt in to create a straight row of raised ground. When you are done, go back and pat down the row down gently to firm things up allowing the ground to become a bit more solid and easier to plant in.
You will want your rows a good 18″ or more apart.
This will allow enough room to get down between the rows without risking injury to the plants. It also is enough room for a rototiller to get in there if this is your preferred method of weeding.
When planting your onion sets, be sure to space your onions 4-5″ apart and plant sets at 1″ deep.
Step #6. Mulch to Deter Weeds
Since onions require very little attention, mulching well is important.
I used to forget about my onions giving my best care to my delicate tomato and pepper plants. When it came time to harvest, my poor onions would be lost in a sea of weeds. Because the weeds stole all the nutrients from the soil, my onions would be small and soft.
I have since learned that mulching really cuts down on the weeds allowing those onions to really grow and flourish.
To mulch simply lay a layer of newspaper down on the ground and cover with cut grass or straw. The newspaper will naturally compost down as the growing season progresses and will act as a barrier limiting the number of weeds that will grow.
Now that I am mulching my raised onion rows, I only need to weed around the very base of each plant. A weedless onion is a happy onion.
It just amazes me how a little time in March can make all the difference come September. 😉
SLCG PRO TIP: Be careful when doing close weeding near young onion sets so you do not accidentally pull out your onion plant. When onions are young, it is best to hold the plant in with one hand and gently pull the close week out with the other.
Step #7. Water Your Onions Correctly
This part can be a bit tricky.
Water too much and you will encourage diseases. Water too little and you will produce small and weak plants.
Mulch is also very helpful with watering, it ensures better drainage and keeps the soil moist longer.
SLCG PRO TIP: if you want a sweeter onion, water more steadily. Be sure to keep water off of the leaves since this can promote fungal diseases. A soaker hose is a perfect option for this. Drought onions tend to be a bit pungent so keep this in mind when growing.
Step #8. Cover or Not to Cover
As your onions grow they will emerge from the ground exposing part of the onion. At this point, it may be tempting to cover the exposed onion with a layer of soil. When I was a new gardener I was given the advice to cover the onion with soil and what resulted was a batch of smaller and softer onions.
My advice to you is to leave your onions as they are. But you will get different answers depending on who you ask. The final decision is up to you, but you can try to cover half and leave the 0ther half go and see what results you get.
Step #9. Diseases to Watch For
The biggest problem I have had with my onions is bolting.
Bolt is when an onion produces a flower about 1/2 to 3/4 of the way through the growing season. This can occur especially if the growing season is wet or chilly and is bad news.
Once an onion bolts, it is pretty much done growing so your best bet is to remove the stalk and flower to see if you can “jump-start” it back.
But the odds of this working are not in your favor. Your best bet is if the onion is large enough, you can harvest your bolted onion, dry, and use it as you normally would. They may be smaller onions but will taste just fine.
Step #10. Harvest
When your onion tops begin to yellow and fall over that means your onions are just about ready for harvest.
You can encourage things by bending your tops over and even loosening the soil around the bulb just a bit. After a few days, pull your onions and let them dry on the ground where they are.
Step #11. Dry and Store
When your onions are finished drying, gather them up shaking off excess dirt as you go. Move them to dry in a safe area until the tops are brown and dry. This should take 1-2 weeks.
I have found an old window screen works perfectly for this. But you can use any solid surface to hold and dry your crop.
Once you are sure your onions are dry, remove the tops and the roots with a pair of scissors. I like to remove the outer skin especially if it is brittle and dry. This just keeps things a bit neater in my pantry.
You can store your onions in mesh breathable bags in your root cellar or pantry if you intend to use them up quickly. Check your supply each week for any onion that is beginning to go bad. One bad onion can spoil several neighbors so it is important to be diligent on this.
Onions will last 2-3 months in a pantry and 5-8 months in a cool dry root cellar.
Step #12. Freezing Onions
Another storing option for onions is freezing.
If you plan to freeze your onions make sure you dice them or slice them before you do. Place your cut onions on a foil-covered cookie sheet and par-freeze first. This will keep the moisture-filled onions from clumping together in an icy mass.
Once par frozen, you can put the onions into labeled freezer bags being sure to remove as much air as you can before your final freeze. By doing this you will keep your onions from getting freezer burn allowing them to last longer.
Whether you are beginning your first garden or a seasoned pro, onions can be a great addition. A simple vegetable to grow and store this option should be on any beginner gardener must-try list.
Learning how to grow bigger onions that are huge, healthy, and organic is a simple and great way to fill your winter pantry.