8 Problems Growing Onions and How to Solve Them

Growing onions is a popular pastime for many of us. According to onions-USA, nearly 7 billion pounds are produced yearly in the US. That’s a lot!

Onions are grown for many uses, such as eating, cooking, and pharmaceuticals. They add flavor to your favorite dishes, such as soups, salad dressings, and stir-fries, while also acting as a side dish with lunch or dinner. 

If you’ve ever tasted raw onion, you’ll be familiar with its pungent smell and intense flavor. However, getting this desirable flavor from your crops can be difficult if you don’t go about it correctly.

If you’re trying to grow your onions at home and take care of them from the start and continue to monitor them until harvest, you will have the best-tasting onions you have ever had.

But there are several things that you should be aware of before you start, including how to deal with potential pests or diseases. By addressing these problems from the beginning, you can keep your onions free of unwanted disturbances.

So let’s look at the common problems growing onions and how to solve them.

1) Small Bulbs at Harvest

If you notice small bulbs or lots of deformed ones at harvest time, this is a sign that your onion crop may have been exposed to cold temperatures for too long.

Even though onions don’t like extreme heat, they’re not very fond of cold weather either. They will perish if left unprotected in freezing conditions. In these cold environments, the leaves of onion plants begin to shut down, and so do their metabolic processes.

small onion bulbs laid out next to each other in soil
Small bulbs are a common problem with growing onions

The root system is still active, but the leaves need sunlight and moderate temperatures to produce enough sugars for bulbs to grow large and round. 

For this reason, it is recommended to plant your onion seeds in early Spring to expose them to their ideal temperatures. Of course, you can plant onions during any time of year, and they will still grow, but a severe frost will devastate them.

2) Onions With Curled Leaves

If your onion leaves are curly, it may indicate poor quality soil or even a lack of moisture in the ground. 

Poor quality soil can be due to different factors such as zinc deficiency. Zinc is used by plants to produce chlorophyll, and if your leaves look withered, it could be due to this. 

Another potential reason for the leaves to curl is the lack of moisture in the soil. Make sure you are consistent with your watering schedule and consider the weather. If it is scorching outside, increase the water, your onions are getting.

Another possibility may be down to the dreaded thrips. More on them later!

3) Growing Onions Problems: Blight

Blight is a plant disease caused by bacterial or fungal infections. Blighted onions will have brownish spots on the outside of the bulb. If left unaddressed, they can spread throughout the entire onion plant leading to its eventual death.

blight on onions has brown/yellow spots
Blight on Onions. Credit: ipm.ucanr.edu

Blights on onions are caused by fungal diseases such as Alternaria or botrytis blight. A common way to prevent blight is by purchasing disease-resistant varieties of onion plants. These cultivars are the best choices for the home gardener since they can survive and grow healthy bulbs without succumbing to fungal diseases like common varieties.

If your onions already have blight remove the affected leaves and stems immediately. Use a suitable Fungicide to slow the spread of the infection and move the plant away from others nearby.

Monitor the spread of the disease until it has subsided by applying the Fungicide where necessary.

4) Viruses

While onions are pretty disease resistant, they can fall to certain viruses. Iris Yellow Sport Virus is one such virus.

Although it is uncommon, the effects can be long-lasting. Symptoms can range from mild forms of mosaic or mottling to severe stunting, dwarfing, and other bizarre shapes.

Once you notice a plant is infested with viruses, they spread quickly to nearby plants through insects like aphids. So the only way to stop the spread is by removing all infected plants.

onions in the ground in a row
Check your onions consistently for symptoms of viruses or infections

5) Onion Seeds Not Germinating

Onions may not germinate if exposed to cold temperatures for too long. Onions need a specific type of soil and air temperatures to grow successfully. In addition, they require plenty of sunlight and adequate moisture.

Your soil temperatures should be above 40°F, but the optimum is 75°F. Make sure to plant onions at the right time of year. Early Spring should provide the best conditions. The pH of your soil should be around 6-7, and it should be deep and loose to give the roots plenty of access to nutrients.

If you have poor quality/rocky soil, which is the wrong pH, try building a raised bed. Raised beds allow you to control the soil quality completely, giving you a better chance of growing perfect onions.

If you’re having trouble getting your onion seeds to germinate, purchasing onion plants and seedlings from a reputable nursery or garden center is the best option. You can also search online for the specific cultivars that will grow well in your location.

spring onions in bunches on top of each other
Plant onions at the right time of year

6) Tops Falling Over

You’ll notice that this is more of an issue with shallots than other onions, but it could happen to any plant as they age. Since the top is usually heavier than the roots, they could start to fall over. This becomes an issue as the plant is not exposed to as much sunlight as it could be.

To correct this problem, you can try staking your onions. You can easily support them by weaving a stake between the branches and tying it off with twine or garden netting. This should prevent tops from falling and keep parts from drooping and breaking off.

stakes in the garden in a row of small plants
Staking onions is a good solution if the tops are falling over

7) Why Are My Onions Not Growing?

If an onion plant isn’t growing as quickly as the others in your garden, it could be due to several different reasons. 

For example, if you notice leaves curling up with brown spots on the underside, it may be because of blights or viruses. You should also check for onion larvae in the soil.

Once germinated, onions start to grow quickly, and their leaves will begin to poke out of the ground. They should be about 6 inches tall after a few weeks and ready to harvest approximately four months after germination. 

Slow-growing onion plants could come down to several factors. Whether it is the incorrect soil pH, lack of sunlight, or even lack of moisture, these are variables that you must monitor to grow consistent crops yearly.

This is why raised beds are a great solution, as they remove any type of inconsistency that you will inevitably encounter when planting in the ground.

onions sprouting from the ground
Onions should be sprouting after six weeks. Credit: MasterClass

8) Thrips

If you notice that your plants are dropping leaves or their foliage is discolored, it could be due to Thrips feeding on the plants. Also known as Thunder Flies, Thrips are tiny insects that, unfortunately, love eating onions.

As they feed, they release a toxin that causes onion leaves to turn gray or white before eventually dying off.

Taking preventative measures like using insecticides is the best way to reduce the chances of infestation. First, be sure to remove any part of the plant that shows signs of thrips and use the insecticides on the remaining parts. Then, continue to monitor the situation until there are no signs of any thrips.

Keeping onion plants spaced out from each other will also help prevent thrips from quickly reaching them.

Thrips on onion leaves. Credit: Greenlife

Final Thoughts On Growing Onions

Onions are a great addition to any garden because they produce delicious and flavourful bulbs. 

However, many different problems can occur with them throughout their life cycle. Therefore, you need to know how to identify and solve these issues before they escalate into something worse.

What do you think of this article on growing onions? Let us know what you think and if you have any other tips to include.

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