How To Grow Large Onions In Your Garden Without Too Much Investing

How many of you love to cook? To be honest, I know how to prepare only several recipes, and those are great, not to be falsely modest. However, besides several pasta recipes which are my specialty, I love a good sandwich. 

And to make one as it should be, you must have larger onion bulbs to use them as a topping. Because of that, here’s this article. Learning how to grow large onions will not just enrich your sandwich, but will also make you proud of your effort.


Why Shouldn’t I Use Two Smaller Bulbs Instead?

Onion pods

Generally speaking, you can always do so. Nothing stops you to take two smaller onion bulbs and use them for culinary purposes instead of bigger one. But, things are not always in favor of smaller onions.

Let’s say that you love onion rings. These are made of raw onions which is deep-fried. Although it seems logical to use smaller onions for this purpose, larger rings are better. Because of their size, smaller quantities of oil will be retained, and the taste will be far better. Also, when you are growing onions, it seems disappointing when the harvesting time comes, and you pull out acorn-sized bulbs from the ground.

But, Larger Bulbs Usually Have Weaker Taste, Do They Not?

Cutting onions

Well, yes… and no. If you have standard-sized onion variety, and you overwater it, so that the bulb grows larger, then the taste will be diluted. But this is not what I’m talking about. I have strived to get the most out of the soil, care and the plant, to get the best possible taste, with the bulb being bigger.

On the other hand, if you exaggerate with fertilizing, it can backfire; although onions are heavy feeders, they can get burned which leads to the withering of the plant and ruined harvest. There are several ways to avoid this, and they will be presented in this article as well.

So, Which Factors Influence The Size Of The Bulb The Most?

Among other things, there are three factors which are crucial in determining how large the onion bulb will grow. Those are:

  • check
    The variety – not all onions are same sized when grown.
  • check
    The soil – the amount of fertilizer, organic matter, and water contained within the soil determines how large it will grow.
  • check
    The Sun – onions require a full day of sunlight and thrive upon it, but too much can drain the water from the soil around the plants.
Effect of eviroment on onions

Also, there are combined factors such as the amount of organic matter in the soil which directly influences how much water is contained and if that extra water is drained further below. Luckily, gardening had progressed enough, so it is possible to affect almost every one of those factors.

What Is The First Thing I Should Do?

Preparing soil

“Plans are nothing; planning is everything,” said General from the WWII and later president of the USA, Dwight D. Eisenhower once. Although this is probably meant in the context of taking back France, this quote is also applicable when it comes to gardening. Therefore, the first thing I have done was to go out and see the situation in the field (pun intended).

The area where I wanted to plant onions and to try to get the biggest possible bulbs was nicely lighted, with loamy soil with sufficient amount of sand. However, I wasn’t satisfied with the amount of organic ingredients. Therefore, I have added about 2-3 inches of compost. In case that you don’t know how to make it, just throw organic waste into the tumbler, and shake it once in every few days.

Of course, this compost doesn’t need just to sit around, I have tilled it into the ground once in a few days for three weeks. This is my standard preparation, and if you have read my other articles about growing vegetables, you are familiar with that. Also, if you notice that your ground has too much clay, add sand to improve drainage. Of course, don’t use sand from sea beaches, that one is rich in salt, and can damage your plants.

As for the acidity of the soil, it was perfect, as my pH tester showed, 6.4. Remember that any pH between 6.3 and 6.8 is suitable for growing onions. However, if you need to apply sulfur to reduce alkalinity, keep in mind that higher levels of sulfur in the soil will lead to more pungent and sharper taste of the onions.

All Right, But Which Seed I Should Choose?

Onion seeds and pods

At this moment, you should choose how you will plant your onions. Two of the most common ways are either from seeds or pods. Seeds can be bought anywhere, and you can even buy some exotic varieties online if you want to try them.

But, seeds have one drawback when compared to pods. Namely, seeds must be sown much earlier, and are overall more difficult to handle. To have the most prominent bulbs possible, you will need one onion on every 5”. This is nearly impossible with seeds, because of their small dimensions; pods are far more accurate.

Also, pods are small onions which are waiting for the opportunity to continue with growing. This is another advantage of the pods. You get them, plant, and they start growing. The process of germination is already passed, so you don’t need to worry about it.

The remaining question to answer is whether you prefer more sweet varieties, or those more pungent? In case that you like the first kind, you can take into consideration Sweet Spanish, Yellow Granex or Walla Walla. Stuttgarter Giant and Giant of Zittau are coming from Europe, and are not as sweet as the others.

In Which Period I Should Sow Them?

If I had to answer in four words to this question, my answer would be “The sooner, the better.” Of course, you need to look after the weather forecast. In case of spring frosts, you should wait for the weather to get better and more favorable. Although the onions are resistant to cold weather (can spend an entire winter covered in snow), pods are still sensitive, so wait until the frosts pass, which is usually somewhere in March.

On the other hand, if the spring starts sooner than usual, feel free to use this to your advantage; make trenches 16” apart, where you have planned your onions to be, and put one pod in every 5”. Cover with soil and water adequately. The usual practice is to gently press the soil around each pod so that the air is pushed out. Onions have small and short roots and require good contact with the ground.

What To Do After This?


After you have planted the pods, all there is left is to apply fertilizer properly and to look after watering. Onions will drink water as long as there is any, so you must dose it correctly. 1-2” of water per week (including rain) is the middle ground; not too much for the bulbs to swell, nor too scarce for them to be stunted.

As for fertilizer, it is known that every fertilizer is rich in three basic compounds which are represented with the NPK index. Nitrogen makes the green parts stronger, Phosphorus is improving the fruit, and the Potassium is the element which regulates good flow and distribution of the previous two. Because of this features, there are two periods of applying fertilizer.

Right after planting, you can apply some form of fertilizer which is rich in nitrogen, so that the leaves will have a good start. At the end of spring or the beginning of summer, you can include fertilizer with more phosphorus. One of the best ones is a fish emulsion since it is rich in said element, and also has a lot of other nutrients, such as minerals and salts. If you are not keen on spending money, you can always make fertilizer at your home.

There is also one alternative which you can take into consideration as well. Microbial Inoculants are not fertilizers, but will help the onions grow. These are consisted of several cultures of beneficial bacteria which will boost the intake of nutrients. Because of that, they can be used together with regular fertilizers.

How To Take Care Of My Onions?

take care of onions

Luckily, there are only several pests which will dare to attack onions, so you need to take a good look. If there are some dried leaves, while the others are still green, it is highly likely that you are dealing with the onion fly.

The best way to deal with these nasty little critters is to remove the top layer of the ground, add some wood ash and cover the soil again. Of course, in case of thrips or some species of mites or aphids, you have a full selection of organic insecticides which can help you to deal with this menace.

Beside pests, a second worst thing which may happen to your precious onions are weeds. They are useless plants which sole purpose is to draw nutrients from the soil and to weaken your vegetables.

Although there is a broad selection of chemical solutions, I’m firmly against using those. Removing them by hand is far healthier, and also contributes to your health and makes you fit and in shape.

Of course, if you are unable to attend your garden on a daily basis, cover the soil with a few inches of mulch. This is a useful approach for both keeping the weeds at bay, and to prevent water from evaporating from the ground.


So, there it is. Knowing how to grow large onions is vital if you have no previous experience, or if you have developed a green thumb, but you need to upgrade things a bit. Undoubtedly, growing these is a matter of feel and control, both of which are vital for a great gardener.

I have to point out that Microbial Inoculants have proven to be far more superior than the rest of the competition, so feel free to buy them!

In any case, your thoughts, opinions, and advice are more than welcome in the comment section below.

Leave a Comment