Onions are nutrient-dense and flavorful ingredients you can add to almost anything.
From salads to casseroles, you can’t go wrong with adding a handful of diced onions to spice things up.
Do you know what’s even more impressive? Because of their hardiness, onions are relatively easy to plant, too.
The key is knowing when to plant onions and how to care for them the right way.
When is the best time to plant onions? Onions are a cold-season crop, so the best time to plant them is in early spring. The cool weather will encourage them to grow tops. And as the weather warms up, that’s the time they form bulbs. If you live in mild-winter areas, plant onions in the fall instead.
What Is the Best Month To Plant Onions?
As with any plant, the best month to plant onions depends on your location and the climate in that area.
Basically, what you want is to make sure that the weather where you are is cool, not cold.
In most cases, this would be around late winter until mid-spring.
Again, if you live in an area with mild winters, you can start planting your onion seeds in the fall or winter.
Still, keep in mind that the leaves, roots, and bulbs develop in temperatures between 55 F and 75 F.
Once the leaves start to grow, you can expect your onions to survive in temperatures higher than 75 F.
Choosing Onion Seeds
Onion plants are very sensitive today, hours, or the number of hours they receive daylight.
Whether they form bulbs or not depends on the number of daylight hours in the region where you plant them.
As the name suggests, this type of onion requires shorter days or about 10 hours of daylight.
It will begin forming bulbs once the day length reaches the 10-hour mark.
Keep in mind that if the top (leaves) does not get enough time to grow lush before the temperature changes, the bulbs won’t grow bigger, too.
This onion variety requires around 14 to 15 hours of daylight to form bulbs.
If you plant long-day onions in an area that doesn’t get that much daylight, don’t expect them to develop bulbs.
Instead, you’ll only get the leaves.
Compared to the other two, this type does not rely on the number of daylight hours where you plant it.
As such, you can plant day-neutral onions in almost any region.
Planting Onions in Different Climates
Plants need different conditions to grow and thrive.
If you want to try your hand at growing onions, focus on getting to know the weather conditions in your area first.
Below are general tips for planting onions in different climates:
Both the amount of rainfall and the level of moisture in the soil can make it challenging to grow onions in the tropics.
A hot, humid climate may cause them to rot in the ground, which is why you want to use well-draining soil to plant onions.
Planting in raised beds or raised rows using fertile, free-draining soil is the best way to go about it.
Onions need constant moisture to develop bulbs. If they don’t get it, the bulbs will most probably split.
For this reason, the general rule of thumb is to water more frequently but make sure you don’t overwater them.
Places that don’t experience extreme heat or cold are the best growing conditions for onions.
Make sure you choose the correct type of onion to plant depending on the number of daylight hours in your area.
You will have better chances growing onion from seeds if you plant them indoors first—around a month or two before the last frost date.
Then, transplant them into your garden as soon as the soil becomes workable.
Again, onions can tolerate the cold but not so much that they can survive extremely cold winters.
In that case, you have to learn how to protect the onion plants from overwintering.
For this, you can add a good layer of mulch or choose to plant them in containers indoors instead.
How Long Do Onions Take To Grow?
For spring onions, you can start harvesting about a month after planting onion sets.
However, if you want the bulbs themselves, you’d have to have more patience.
Onions have a long growing season, usually taking about 90 days to reach maturity.
Some even take as long as five months to be ready for harvest.
How To Plant Onion Seeds
While it’s way easier to grow onions from bulbs, it’s possible to learn to grow them from seeds, too.
Just make sure you follow these steps to the T, and you should be fine.
Step 1: Choose the Right Seed Type
Depending on the growing zone you live in, you would want to pick the correct type of onion variety to ensure your success.
Short-day onions will grow best in areas under Zone 7 or warmer.
These onion varieties include Vidalia, Red Creole, and Red Burgundy.
If you’re from an area with colder climates, such as those categorized as Zone 6 or cooler, opt for long-day onions.
These can include White Sweet Spanish and Copra onions, as well as Alisa Craig onions.
If these two types don’t meet your requirements, you can always plant neutral-day onions, which grow in most regions.
Step 2: Start Seeds Indoors
Once you have the seeds, you can get ready to start them.
It’s important that you make sure you use the seeds you buy within two years after purchasing them. Otherwise, they might not sprout at all.
To start onion seeds, plan to plant them around eight to 10 weeks before the average last frost date.
During this time, the seeds will germinate into seedlings healthy enough to transplant outdoors.
Using a four-inch-deep container, plant the onion seeds following the instructions from the packet.
More often than not, this means sprinkling the seeds on dampened starting mix and lightly misting them with water.
Lastly, cover them with about an eighth of an inch more of the starting mix.
Step 3: Wait for the Seeds To Sprout
Place the container in a warm spot (about 70 F to 75 F).
If you live in a colder region, you can try using a heat mat to achieve the right conditions.
Cover the container with plastic or a humidity dome, and wait around seven to 10 days for the seedlings to emerge.
Step 4: Lower Humidity and Heat
Once you notice the seedlings, transfer the container to a cooler spot and remove the humidity dome or plastic.
Do this all while making sure the soil is kept moist and fertilized.
For fertilizer, you can use compost tea or diluted fish emulsion.
Step 5: Transplant the Seedlings in Your Garden
Seedlings are still very sensitive, so you want to harden them first before transplanting them.
To do this, gradually expose the seedlings to the conditions outdoors by leaving them outside for a couple of hours each day.
Then, place them back indoors for the night.
It’s best to do this around eight to 12 weeks before the last frost date in your region.
When they are about four inches tall, that’s when you know they are strong and healthy enough that you can transplant them into your outdoor garden.
How To Water Onions
As soon as you plant them outdoors, remember to give the plants enough water regularly.
Allowing the soil to dry just as the plants are forming bulbs might cause the bulbs to split.
Step 1: Water During the Day
As with any plant, water them in the morning as opposed to midday or evening.
Watering plants when the sun is high up will only cause the water to evaporate.
On the other hand, watering at night might result in wet foliage, which can encourage the development of diseases.
Step 2: Give the Plant Just Enough Water
Assuming you plant them in a mix of well-draining soil, give your onion plants a thorough soak every week.
This means giving them about an inch of water every seven days but don’t let the soil become soggy.
Doing this regularly means the soil around the bulbs doesn’t harden, giving them enough space to grow even bigger.
Step 3: Stop Watering and Allow Them To Mature
Notice the leaves falling over?
That’s the time when you need to stop watering your onion plants and let them finish maturing.
Leave them be for about a week or two before getting ready for harvest.
How To Grow Onions and Harvest Them
The last phase of learning how to grow onions is finding out how to harvest them.
In this stage, what’s important is to allow the bulbs to dry after pulling them out from the ground.
Here’s how to do this:
Step 1: Pull Out Each Plant
Onion bulbs in full size are about three to five inches in diameter.
You can also try checking for ripeness by looking for a soft spot about two to three inches above the bulb.
The best way to tell when it’s time to harvest is when about 80 percent of your onion plants already have bent tops.
When this happens, go ahead and harvest each bulb.
Step 2: Cure the Bulbs
Pick a cool, dry spot where you can spread the bulbs next to each other and allow them to air-dry.
It’s very important that you do this with the tops still on.
Wait for about a month before you prepare them for storage.
Step 3: Ready Them for Storage
Lastly, cut off each bulb’s top, leaving only about an inch or two behind.
Carefully brush away any dirt, and that’s it!
You can bring them store them as you would store onions, sell them, or give them away to friends and family.
If there’s a vegetable present in all cuisines, it is onion.
Onions are not only delicious but also packed with nutrients. In fact, it is loved for its ability to help lower inflammation and fight off free radicals.
For these reasons, more and more homesteaders are choosing to include onions in their home gardens.
And with this guide, we’re confident you are well on your way to harvesting your own batch of fresh onions very soon.
3 thoughts on “When To Plant Onions – Planting Guide 2023”
You can grow onions from seed during late fall, whether you live in a warm or cold climate. Other than autumn, early winter is best for hotter regions, while for cooler ones, early spring is better.
That was the best post I’ve read on onions! Thank you so much!