Why Are My Onions So Small? How To Make Onions Bigger?

Onions are one of the indispensable spices in many dishes of every family, so they are often loved to grow in the garden, styrofoam, or trays in the house.

Onions are easy to grow, easy to care for, and do not require a lot of technique when growing. However, one of the problems many gardeners face is the size of the onion.

After the process of caring and fertilizing, you still only get onions that are much smaller than the standard size. Why are my onions so small? Perhaps this is the question you will have to regard.

Onions that are small and not up to the standard size can be due to a variety of reasons. Let’s find out in detail the causes of small onions in the article below.

Why Are My Onions So Small? How To Have A Bigger Onion?

The cause of your onions being smaller than usual can stem from seeds, inappropriate climate, the distance between onion plants, nutrients in the soil, etc.

In addition, you may also face problems with water, sunlight, pests, and other types of insect damage. Here are the most common causes that you need to consider.

1. The Type Of Onion Is Not Suitable For The Climate Where You Live

Onions are usually divided into 3 main types short-term onions, regular onions, and long-term onions. With each of these onions, they will be suitable for the weather and climate conditions of each region.

The key to getting the right size onions is choosing the right type of onion for the climate and weather to facilitate their growth.

Short-day onions: Usually grown in the southern regions of the United States in the fall or winter. If you grow this short-day onion in the northern part of the United States, the onions will not be as large as they are grown in the southern United States.

Growing time in the southern US is 110 days to harvest and 75 days in the northern US. However, in the northern part of the United States, you cannot plant onions in the fall because winters here are too cold, and frosty.

Short-day onion plants will begin to form bulbs if they receive 10 to 12 hours of sun each day. Varieties include Red Creole, Texas Super Sweet, White Bermuda, and Yellow Granex.

Common onions (Average harvest time): They are generally planted further north than short-day onions, but further south than long-day onions. The assortment includes Candy, Super Star, and Red Candy Apple.

The average time to harvest a typical onion is 100 days. You should plant onions mid-season in spring in colder northern regions and fall in warmer southern regions.

Ordinary onions will bear fruit if they receive 12 to 14 hours of sunlight each day.

Long-day onion: These are commonly grown in the northern part of the United States including varieties like Ailsa Craig, Copra, Highlander, Red River, and Red Zeppelin. The time to harvest this long onion is usually 110 days.

Long-lasting onions should be planted in early spring after the frost of winter has passed and harvested in late summer. Long-term onions in the northern United States tend to be less sweet than in other regions, so they are easy to store.

Read more: Cut Onion Tops While Growing – The Truth Will Surprise You

2. The Distance Between The Onions Is Too Thick

Choosing the right variety of onions for your climate is important, but growing them the right way will help you harvest larger onions.

The best distance between each plant is 6 inches apart. This distance is appropriate so that each onion has its own space and it can grow to the maximum size.

If you plant onions too thickly, the onion plants will not be guaranteed the amount of light, the amount of water they receive each day, and especially the nutrients in the soil that are not enough for them to absorb.

In addition, you should plant rows at least 12 inches apart to facilitate care, watering, and fertilizing to avoid uneven distribution of water and fertilizer in an area.

In particular, another serious problem in the process of growing onions is that weeds grow everywhere and encroach on the space of onion plants. You can easily find a lot of weeds growing around onion plants as well as clinging to onion stems to grow.

Your job is to regularly get rid of these weeds by rooting and drying. Then, burn them and compost them to use as fertilizer for the next crop.

Weeds grow very quickly and will encroach on the space and nutrients of the onion plants, making it impossible for them to grow normally and resulting in very small onions.

3. Small Onions Due To Insufficient Nutrients In The Soil

The source of nutrients is always an extremely important factor for any plant. To get big and delicious onions, you need to ensure the quality of the soil in terms of nutrients, porosity as well as good drainage.

Each onion plant needs a fixed amount of nutrients in the soil to absorb and nourish the tubers in the ground. Therefore, you need to fertilize the soil to provide adequate nutrients for each onion plant.

You need to treat the soil to make them loose because onions will not be able to grow in conditions that are too tight and difficult to move. The soil needs to be well-drained because too much water will cause the onions to stagnate, rot, and stop growing.

The ideal pH for growing onions is between 6.0 and 6.8, so if the pH is too high or too low in the soil, it will also make it difficult for the onion plants to absorb nutrients.

If the soil pH is too low (acidic), you can add lime (calcium carbonate). If the pH in your soil is too high (alkaline or basic), you can add sulfur.

Finally, you need to make sure to fertilize early, mid-season and late-season so that the onion plants have enough nutrients during each critical period.

While the onion leaves are growing, you should make sure to use a fertilizer with a high nitrogen content as they will support the onion plants to grow well, giving the ideal number of leaves (13 onion leaves per plant) to have large onions.

Read more: How Many Onions Grow From One Bulb?

4. Small Onions Due To Not Getting Enough Water Every Day

In addition to fertilizer, water is also an indispensable ingredient when taking care of onion plants.

Normally, onion plants need sunlight from 10-14 hours a day, so to ensure the survival of the plant they also need a certain amount of water each day.

Therefore, you need to make sure to always water your onion plants adequately by checking the moisture in the soil.

You should water in the morning so that the sunlight dries the onion leaves to avoid water getting on the leaves and creating favorable conditions for fungi that cause diseases to the leaves and onions.


The size of an onion depends on many different factors such as the variety of onions, the climate in your area, the distance between the onion plants, nutrients, pH, water, and light each day.

So to overcome the situation of small onions and not reaching the standard size, you need to follow these principles:

  • Choose an onion variety that is suitable for the climate where you live
  • Onions are spaced at least 6 inches apart and rows at least 12 inches apart
  • Ideal soil pH from 6.0 to 6.8
  • Plant in an area with 10 to 14 hours of sun each day
  • Water when the soil is dry
  • Fertilize and weed regularly
  • Plow the soil loosely and avoid waterlogging for onions

Also, if you want to learn more about care and tips to get bigger and sweeter onions, don’t forget to discuss more here.

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