How Long Do Onions Take To Grow: A Journey From Seed to Cutting Board


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Onions are a delicious and versatile vegetable that can be used in a variety of dishes.

In just a few months, you can grow your own onions to use in your kitchen.

How Long Do Onions Take To Grow
How long do onions take to grow

The time it takes for onions to grow will depend on the type of onion you are growing, but while you wait for them to grow we’ll teach you how to care for them and what to look for when they are ready to harvest.

How to Plant Onions

Onions are a cool-season crop and they can be started from seed in the ground weeks before the last frost occurs.

As soon as the dirt can be tilled, you can plant onion seeds.

They will, however, need full sun for at least 12 hours a day to establish the bulb.

Without 12 hours of sun exposure, the bulb won’t develop very big, or at all, and your harvest will be a little disappointing.

How to plant onion process
How to plant onion

Before planting onions, test the pH of the soil.

For Onions – The pH should be between 6.0 and 7.0. There are products you can buy to increase or decrease the acidity levels of the soil.

Once you have found the right spot to plant onions, and the soil is at the right pH, create small holes 6″ apart and 1″ deep.

Put the seeds in the holes, fill the holes with dirt, and give them a good drink of water.

You can also grow onions from bulbs.

If you are planting onion bulbs, only bury them deep enough to cover the bulb, but leave the tip of the onion above the soil level.

Type of Onion

Planting onions is the same across the board, but how long onions take to grow will depend on the type of onion.

types of onoins

Let’s take a look at the seven most common types of onions.

Yellow, White, Sweet, and Red Onions

These standard-shaped onions take quite a long time to grow.

It can take them anywhere from 100 days to 175 days for yellow onions to reach maturity and be ready for eating.

Since onions take so long to mature, try starting them indoors earlier in the season, and then plant them in the garden when they are warm enough.


Shallots are a type of much smaller onion, and they can be harvested sooner.

If you want to harvest green shallots, you can harvest them within 30 to 60 days.

If you want to wait for shallots to mature, you can harvest them in 90 to 120 days.

Green Onions

Green onions grow extremely quickly. You can harvest them after only a couple of months.

Different types of onions
Types of Onion

The cool thing about green onions is the stalks will regrow.

Whether you cut the stalks from the garden, or buy green onions with the roots still attached at a grocery store, you can continue to cut more green onion as it grows.

The green onion in your garden has to be watered constantly, and the green onion from the grocery store should be placed in a shallow dish of water, so the water level is just covering the roots.

You can get about 4 or 5 harvests from one stalk of green onion before they stop producing more edible stalks.


Leeks take 120 to 150 days to grow.

This type of onion should be started indoors before the spring, and transplanted outside after the final frost.

How to Harvest Onions

How do you know when onions are ready if they are growing under the soil where you can’t see them?

How to harvest onion process
How to harvest onion

No, please don’t dig them up to check on the progress and put them back, there’s an easier way to tell.

When the foliage above the soil begins to turn yellow, stop watering the soil.

This will let the onion start to dry out as it continues to mature to avoid rotting.

You’ll start to notice the leaves start bending towards the earth, showing that the plant is drying out. This is fine and actually encouraged.

When you notice half of your onion garden has bent leaves, you should bend the rest of them by hand.

Mark your calendar for two weeks after you bend the rest of the leaves.

After the two weeks have passed, it’s time to dig up your onions, but don’t pull directly on the leaves.

Instead – You should loosen the soil around the onion and lift it by the bulb. Then you can cut the leaves and the roots off, and leave them in a dry area for a couple of weeks.

When the outer layer of the onion looks dry and crispy, they are ready to be stored until they are eaten.

Storing Onions

If you store your onions properly, they can last up to three months.

To store onions, you will need to keep them in a cool, dry place.

Pantries, cellars, basements, and garages are some of the best places to store onions, as long as there is no moisture.

Growing Potatoes in Soil
Keep onions away from potatoes

If you hang the onions in a mesh bag, similar to what you would get at a grocery store, the onions will get good ventilation and prevent any moisture from ruining your hard work.

Keep your onions away from potatoes!

Potatoes release a gas that causes the onion to rot. The gases will cause the onion to spoil and the entire crop will be ruined.

Final Thoughts

Knowing that onions will only take a few short months to mature, it’s time to get everything ready for planting.

Find a spot that has full sun, has the right pH, and isn’t too far from the hose, and you’re ready to plant some seeds or bulbs!

And don’t forget – once they are harvested, you can store them in a cool, dry place for months. Enjoy!

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