Select Page

Growing Onions From Seeds The Simple Way

Growing Onions From Seeds The Simple Way

With the summer seasons on the horizon, many people love to love to slip on their gardening gloves and start to plant many flowers and vegetables. For someone who isn’t too savvy in the world of gardening it can be slightly intimidating, however, gardening as a whole isn’t a strictly exact science and even experts can make mistakes.

One of the best starter grows are onions as they are a very hardy vegetable that can be planted in summer months or the winter months, without any worry of damage and have a much higher success rate.

In this article, I will be sharing with you how to effectively grow onions from seeds.

Choosing Your Seeds

When it comes to choosing your onion seed, there are three different categories that you can choose from and they depend on which plant hardiness and growing zone you reside in. If you so happen to choose the wrong type of onion for your zone, you may not see the higher success rates that onions are known for.


  • Zone 7: Warmer climates, short day onions.
  • Zone 6: Colder climates, long day onions
  • Any Zone: Day neutral onions

If you are unsure of which zone you live in, there are many online guides and tools that can assist you in finding your zone.

Starting Dates

You should allow 8 to 10 weeks of growing your seeds before the colder weather comes into play. Grow them indoors before transporting them outside. Allowing them to grow indoors will give your seedlings a head start and allow them to successfully germinate into healthy seedlings before moving them outdoors.

The Growing Process

Filling Your Container

Find a shallow container and fill it with a dampened seed starting mix. Your container should be at maximum 4 inches deep and should contain drainage holes, the size and shape of the container doesn’t really matter as long as it is 4 inches deep.

Planting Your seeds

Most seed packets have detailed instructions on how to plant specific seeds, however, many of us tend to throw the packets away without thinking but don’t worry! You can still plant them even without the exact instructions the packet provides.

To start with, sprinkle the seeds over dampened soil and mist them lightly with water. Proceed to cover them with around ⅛ inch layer of seed mix and gently pat the soil by hand.

Warmth of Your Seeds

There are two ways you can keep your seeds warm and damp until they sprout. The first way is by using a humidity dome which will help to maintain the ideal humidity and temperature conditions to maximise germination.

If you don’t own a humidity dome the next way is to simply cover your seeds in starting mix and cover them with plastic.

The important part here is you need to keep your seeds somewhere warm in temperatures of around 70 to 75 degrees Fahrenheit. If you live in colder climates and struggle to maintain these temperatures, you can always use a heat mat.

Humidity and Warmth Limitations

Once your seedlings have sprouted which should take 7-10 days but in some cases slightly longer, you should be ready to limit the humidity and warmth of the seedlings. Remove your humidity dome or if you used a plastic covering, completely remove it and transport your sprouts to a cooler location.

It’s important to keep your soil moistened and ensure to fertilize it. Any type of fertilizer is fine, however, if you are unsure of which type to use you can do a little research online as many experts have written articles about the best fertilizers.

Transportation of Your Seeds

Before you transport your seeds outside you should harden them for 4 weeks prior to the actual transportation. This is a rather slow process as you need to slowly introduce the seeds to the outdoors first.

The way in which this is carried out is by placing them outdoors first in a sheltered spot for several hours and then allow them to be brought back inside for the rest of the day. Continually increase the exposure to the outdoors gradually every day until you are able to leave them outside overnight.

The reason for hardening your seeds is that is will allow them to adjust to colder temperatures better, along with decreased watering and sunlight.

It is very important to not put your seeds outside straight away without the process of hardening as this can potentially kill your plants by sending them into shock.

The Actual Planting of The Onions

Before you actually put your seeds in the ground, ensure that they are a minimum of 4 inches tall as this will help to ensure the plants are strong enough to tolerate the outdoor environments. In preparation of this, you should prepare a well-draining and phosphorous rich soil.

Make sure the soil is in a spot that receives at least 5 hours of sunlight per day, as this will ensure the healthiest plants.

To prepare the soil spread around a ½ inch of fertilizer across the soil and then proceed to mid it to a depth of around 8 inches. This is the time to make sure your soil is soft and is free of all lumps, clumps and debris.

Plant your seeds a minimum of three to five inches apart as this will give your plants plenty of room to grow and thrive. Create a small hole in the soil and place your seeds gently into the hole and push the dirt back into place.

Once all of your seeds have successfully been transplanted into the soil, water them enough to dampen the soil. Always ensure to water the onions frequently as the biggest mistake most beginners make is letting their onions dry out by not watering them enough.

The Growing Process

Your onions are now maturing into bulbs and as this happens you should gently pull the soil away to reveal their tops. The leaves of your bulb shouldn’t be the only part of the onion that is above ground, the bulbs should grow above ground too.

If the bulbs will not develop above ground you may need to remove some of the soil surrounding them so that the only part left in the ground are the roots and the bottoms of the bulbs are left in the soil.

Harvesting of The Bulbs

As you check the growth of your plants, the optimal time to begin the harvest of the onions is when they are around two to three inches in diameter. Begin by bending the plants to the ground and give them between five and seven days to dry out and turn brown.

Optional: You can trim the leaves down if you so desire or keep them longer to braid the onions as you would with garlic. This is completely up to you.

Once the outer layer of your onion has browned and dried, you can remove them from the ground and place them in a container for storage that is dry, dark and warm with plenty of ventilation.


Growing vegetables may seem complicated at first and even if you are feeling intimidated, don’t be! Anyone can plant and successfully grow any plants and it will soon become second nature to do so, you will be an expert in no time.

I hope this guide provided you with an insight on how to grow onions successfully and you will be fully prepared for the next planting season!