Do you always have onions in the kitchen? Do you want to grow more in your garden, like I do?
We have more than 300 onions planted in our garden right now. When they are ready to be picked, I store them whole for a few months and then freeze and dry the rest. Each year I have a goal to grow enough to last me until the next year. Although I haven’t achieved that goal quite yet, I get closer each season.
You make think since I have so many planted that growing onions is a no-brainer for me.
The truth is, onions are a little bit (ok a lot a bit) finicky. I plant a lot because every season is different, and the weather in Arkansas can really mess up the size of the bulbs because the temperatures change all the time.
Because I keep trying to get more onions, I’ve learned a lot about how to grow them over the last eight seasons. I’ve also learned a lot about what not to do.
I dive into the details on our latest podcast. You can listen to that below or continue reading.
Onions are a staple in many home gardens Their versatility in cooking makes them an essential ingredient in everything from soups and stews to sandwiches and salads However, it can be frustrating when the onion bulbs you harvest are smaller than expected. If you’ve wondered “why are my onions so small?” there are several factors that could be the culprit. Read on to learn the top reasons for small onions and tips to help you grow large, robust bulbs.
Choosing the Right Onion Variety
One of the most common reasons for small onions is simply planting a variety that isn’t suited for your climate. Onions come in short-day, intermediate-day, and long-day varieties. Short-day onions form bulbs with 10-12 hours of daylight and are best for southern regions. Long-day onions need 14-16 hours of light to bulb and do well in northern zones. Intermediate onions fall in the middle at 12-14 daylight hours.
If you plant a short-day onion in a northern climate it likely won’t get enough light stimulation to form a large bulb. Similarly long-day onions planted too far south may bulb prematurely, resulting in small onions. Be sure to select a variety matched to your growing zone. Check the number of daylight hours required on the seed packet. Talk to local gardeners or your county extension office for the best onion varieties for your area.
Preventing Early Bulbing
Cool, fluctuating spring temperatures can also cause onions to bulb early, leading to small bulbs at harvest. Onions are triggered to start forming bulbs once day length reaches their optimal hours and temperatures are consistently warm, above 60°F (15°C).
If cooler weather prevails after planting, the onion may be fooled into thinking it’s later in the season and begin bulbing too soon. Warm days followed by cold snaps exacerbate the problem. Unfortunately, once an onion starts bulbing, there’s no going back – the bulb won’t get much larger.
To prevent early bulbing, don’t plant onions too early in spring. Wait until soil has warmed and danger of frost has passed. Provide row cover or cold frames if needed to maintain warm soil temperatures. Avoid planting long-day varieties too far south where cool weather is still common when their optimal day length arrives.
Plant Spacing Issues
Planting onions too close together can also limit bulb size. When crowded, onions must compete for water, nutrients, and light. This stresses the plants, reducing their ability to form large bulbs. Follow seed packet spacing guidelines, allowing enough room between onion plants and rows.
As a rule of thumb, allow at least 4-6 inches between plants and 8-12 inches between rows. Wider spacing may be required for large varieties. Thin onion seedlings promptly as they grow to prevent overcrowding. Keep weeds clear so onions don’t have to share resources.
Insufficient Nutrients
Nutrient deficiency is another factor leading to small onions. Onions are heavy feeders that require consistent, even moisture and soil rich in nutrients to reach full bulb potential. Depleted soil lacking sufficient nitrogen, phosphorus, or potassium will reduce bulb size and plant vigor.
Have your soil tested to determine any deficiencies. Amend soil as needed before planting with compost or organic granular fertilizers. Side dress growing onions monthly with a balanced organic fertilizer. Ensure even moisture through mulching and diligent watering. Compost tea or fish emulsion provide an extra nutrient boost.
Planting Too Deep
Finally, planting onion sets or transplants too deeply can inhibit bulb growth. Onions form bulbs best when the top 1/3 of the bulb is exposed. If planted too deep, the bulbing process may be slowed or stunted, resulting in small, misshapen onions.
When planting sets or transplants, don’t bury them more than 1 inch deep. Push sets into the soil just until the tip is covered. For transplants, plant at the same depth they were growing in pots. Check that the soil level hasn’t buried the tops after watering or rainfall and adjust as needed.
What to Do with Small Onions
While disheartening, some small onions in a harvest are normal, even if you do everything right. Luckily, they aren’t destined for the compost bin! Cure any small bulbs fully along with the rest of your crop. You can then replant them in fall as sets the next season. Often, small onions will grow bigger when replanted for a second year.
The small cured bulbs also make great storage onions through winter. They lack the moisture content of their larger counterparts and will keep longer in storage. Though not ideal for large recipes, the petite onions work well chopped or minced in cooking. Their mild flavor is perfect in salsa, sauces, soups, and stews.
Of course, you can always use small onions fresh! Thinning green onion bunches provides mini onion bulbs perfect for topping salads, tacos, and more. So don’t despair over those small onions. With proper curing and storage, they’ll add flavor to meals for months to come.
Key Tips for Growing Large Onions
- Choose an onion variety suited to your climate zone’s day length
- Allow enough space between plants and rows for bulbs to size up
- Plant when soil is warm to prevent early bulbing
- Ensure soil is rich in nutrients and maintain even moisture
- Plant bulbs or sets no deeper than 1 inch
- Cure and store small onions to use through winter
With the right variety selection, spacing, care, and planting depth, you’ll be harvesting armfuls of big, beautiful onions from your garden in no time. Paying attention to these key factors will help you diagnose and prevent small onions going forward. Don’t let disappointing bulbs get you down. Try again next season using these tips for onion success.
Planting the wrong onion types
Planting the wrong kind of onion is one of the most common mistakes people make when they try to grow them. This is especially true if you’re buying your seeds, sets, and transplants from an online source. You can buy intermediate-day (also called day-neutral) onions, short-day onions, or long-day onions. Which ones you pick will determine whether you harvest bulbs or just green onion tops.
If you are wanting large bulbed onions rather than green onions, you will plant the type of onions depending on your latitude. If you are in the US, find your location on this chart to determine which kind of onion is best suited for you. In many areas, like mine, I can plant both short-day and intermediate-day onions, but long-day onions would never bulb for me.
Planting sets instead of transplants and vice versa
Have you ever heard of sets of onions? They are those tiny onion bulbs that look like little onions. Transplants look like green onions with a long green stem and roots at the bottom. I made a mistake my first season when I went into the store and grabbed the sets, hoping they would grow big bulbs. Sadly, all I harvested that year were green onions.
It’s impossible to say for sure, but I think those were long day onion sets. To be honest, they were probably meant to be grown as green onions in my area. They grew very long, beautiful stems…but no onion bulbs. The next year, I learned my lesson, bought the transplants and they grew into huge bulbous onions.
Because of this, I thought wrongly that sets are for green onions and transplants are for onion bulbs. But then I started to see northern friends posting about growing sets and having huge success. So, then I started to wonder? What is actually right here?.
I looked into this topic a lot and found that even on reliable university extension websites, the answers are not all the same. It depends on where the source is found.
This has led me to believe that learning how to grow onions, more than any other crop perhaps, is entirely dependant on the climate you live in. The very best source you can use is your local university extension (find yours here). I — and other gardeners online — don’t live where you live and our experience most likely won’t be the same as yours.
As you learn how to grow onions (which ones to plant, when to plant them, how long until the harvest, etc.), ), be SURE that you know where the source you’re reading about is located.
When it comes to planting onions, whether you choose sets or transplants, the most important thing is to pick the right day-length onion.
Why Are Our Onions So Small?!
FAQ
Why won’t my onions get bigger?
Why are my onions stunted?
Why are my onions so small?
Also, early flowering due to fluctuating temperatures causes small onions. Finally, a lack of nutrients due to competition or poor soil also causes small onions. We’ll look at each of these factors in turn, but let’s start with choosing an onion variety that is compatible with your climate.
Is it bad to eat a lot of onion?
Excessive consumption of onions can lead to gastrointestinal problems such as irritation, reflux, pain when defecating. The breath may also have an unpleasant odor and there may be a change in the color of the teeth.
What happens if you get small onions?
When farming onions, getting small onions is a significant concern; this might damage your entire production, which will affect your earnings. Onion cultivars are classified into intermediate-day, short-day, and long-day onions.
Why do onions fail to grow?
When onions fight for sunshine, moisture, and minerals, they frequently fail to develop many leaves as plants require to develop huge bulbs. Onions have weak tubers, making them weak rivals against adjacent weeds. Mulch the soil beneath onions with a thick coating of dried leaves, crushed leaves, or cleaned hay to keep weeds at bay.
Why are my onions shrinking?
When there’s a crowd, bulbs start shrinking and the fight for nutrients gets real. Why are my onions so small? Onions may grow smaller if they are not given proper space.
Why do onions grow bigger?
The number of leaves produced by the onions before the days shorten impacts the growth of the onion. As a result, the sooner you put the plants, the bigger your onions will become. Growing an onion species that is not suitable for your environment can lead to smaller onions. How Do I Get My Onions To Grow Bigger?