If you’re wondering “why aren’t my onions growing?” one of these common issues could be to blame.
Growing onions is a hugely popular past-time for vegetable gardeners around the globe. It might seem like a simple job, but there are many things that could go wrong with your crop and ruin a possible harvest.
These issues can usually be avoided by doing simple things like choosing the right types of plants to grow, feeding and watering them regularly, and giving them the space they need to do well.
If you want to learn how to grow onions, these eight common issues shouldn’t scare you. With a few tips from a pro, you’ll have everything you need to be successful.
It’s easy to mess up when you grow onions at home, but onions are a tasty crop (credit: Getty/Wayne Farrell / EyeEm).
Drew is a former professional gardener who also specialized as a grower of vegetables, fruit, and herbs. He worked in several walled gardens and grew edibles for chefs, and to sell to the public. In the kitchen gardens, onions were a common crop, and he has grown and picked many kinds of onions over the years.
Growing onions from seed offers many benefits – more variety options, cheaper costs, and earlier harvests. However, it also comes with unique challenges. Onion seeds can be tricky to start and grow successfully. Below are some of the most common problems when growing onions from seed, along with tips to help troubleshoot these issues.
Problems with Onion Seed Germination
Getting onion seeds to reliably sprout can be one of the biggest obstacles. Here are a few reasons you may struggle with germination:
Starting Too Early
It’s tempting to get an early jump on the growing season by starting onions inside weeks ahead of your last expected frost. But onion seeds germinate best at soil temperatures between 55-85°F. They simply won’t sprout if it’s too cold. Wait to start seeds until about 4-6 weeks before your average last spring frost date.
Planting Too Deep
Onion seeds need light to germinate. Plant them too deep and they’ll struggle to emerge. Sow seeds just 1⁄4-1⁄2 inch deep in seed trays or pots. Cover lightly with seed starting mix and mist to water in.
Overly Wet Soil
While onion seedlings need consistent moisture, soaked soils can inhibit germination. Allow the starting mix to dry out slightly between waterings. Onion seeds may rot if planted in a constantly soggy medium.
Improper Storage
Onion seeds lose viability when stored in hot humid conditions. For best germination rates store seeds in a cool, dark place in an airtight container. Refrigeration can extend viability. Only buy seeds from reputable sources and check expiration dates.
Young Onion Seedling Problems
Once sprouted onion seedlings face hazards like damping off nutritional deficiencies. and more
Sowing Too Densely
When starting onions indoors, it’s tempting to plant seeds close together to maximize space. But overcrowded containers cause seedlings to stretch and become leggy as they compete for light and nutrients. Sow seeds 1⁄2-1 inch apart and thin later.
Damping Off Disease
This fungal disease causes onion seedling stems to rot at soil level, killing the plant. It thrives in cool, wet conditions. Allow containers to dry between waterings, provide plenty of airflow, and avoid overcrowding to prevent damping off.
Nutrient Deficiencies
Onion seedlings need consistent nitrogen feeds to grow healthy greens and develop bulbs later on. Use a balanced liquid fertilizer every 2-3 weeks at half strength after seedlings emerge. Goes signs of deficiencies are yellowing, stunted plants.
Light Issues
Without sufficient sunlight, onion seedlings get tall and weak. Make sure to grow seedlings in a bright, south-facing window or under grow lights. Supplement natural light with 14-16 hours per day of artificial light.
Troubleshooting Young Onion Transplants
Transitioning onion seedlings from indoors to the garden comes with potential pitfalls:
Transplanting Too Early
Eager to get seedlings in the ground? Don’t rush it! Onions can’t tolerate any frost. Wait until soils have warmed and nighttime temps stay above 40°F before hardening off and transplanting.
Poor Hardening Off
If onion seedlings aren’t properly hardened off, transitioning from indoors to outdoors, they’ll suffer transplant shock. Harden off gradually over 7-10 days, bringing plants outside for increasing periods of time.
Overcrowding
Give those onion roots room to expand. Overcrowded bulbs will be smaller. Follow seed packet spacing guidelines, usually 4-6 inches apart in rows 6-8 inches apart. Wide spacing also allows for air circulation.
Burying the Stems
Don’t plant too deep. Onion bulbs form right at soil level. If stems and leaves are buried, they can rot. Plant onions with just the root end in the ground and stems exposed.
Forgetting to Water
Seedlings dry out quickly outdoors. Until established, water transplants daily or every other day if rain is lacking. Prioritize consistent moisture the first 2-3 weeks after transplanting.
Preventing Common Onion Growing Problems
Here are some tips to avoid issues through the growing season:
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Test soil and amend as needed – onions like fertile, well-draining soil with plenty of nutrients. Incorporate compost or aged manure before planting.
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Use drip irrigation – wet foliage is susceptible to fungal diseases. Drip irrigation targets water to the soil.
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Weed religiously – onions do not compete well with weeds for water and nutrients. Keep area around bulbs weed-free.
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Side dress with fertilizer – scatter high-nitrogen fertilizer around plants every 3-4 weeks to fuel bulb growth.
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Control pests – onion flies, maggots and thrips can damage developing bulbs. Use floating row covers.
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Allow drying before harvest – bulbs left wet in ground are prone to rotting. Allow 2-3 weeks drying time before gathering bulbs.
While growing onions from seed has challenges, paying close attention to seed starting, plant care, and growing conditions can help overcome common issues. With experience and troubleshooting, you can successfully grow onions from seed for an inexpensive, steady harvest.
Not feeding crops sufficiently
Fertilizing onions is an important part of home maintenance that needs to be done if you want to grow the biggest bulbs. When you plant your onions, you should add fertilizer, and you should keep feeding them during the growing season. Nitrogen (N), phosphorus (P), and potassium (K) are three important nutrients for plant health that are found in plant fertilizers. The numbers on the packaging of any plant fertilizer will show how much NPK it contains.
When onions are planted, they need a balanced fertilizer to help their roots grow in a healthy way. About a month later, they need a high-nitrogen feed, which should be done every three weeks. If you want to grow onions, you can use onion sets or seeds. You can plant hardier onion sets in the fall. Any onion sets planted in fall should be given a dose of high-nitrogen fertilizer in spring. A good example is the Hi-yield Ammonium Sulfate fertilizer from Walmart or Calcium Nitrate from Amazon.
Dominique Kline, Farm Manager at The Hope Farm, explains that onions have high feed requirements and a close eye should be kept on the crop to identify when to stop feeding your bulbs.
Dominique says, “Onions are surprisingly heavy feeders; they act more like a leaf crop than a root crop and depend on high nitrogen for plenty of foliage growth to support later bulb growth.” ‘We recommend a 5-10-5 ratio for your fertilizer. Stick to a regular fertilization schedule until you see the bulbs getting bigger and the soil cracking around the base. This means you don’t need to fertilize anymore. ’.
Before planting the crop, putting down a lot of well-rotted manure or homemade compost will also give it a lot of important nutrients. Mulching around the crop will also add nutrients as the material rots down. It’s possible that your onions didn’t grow as big as they should have if you didn’t feed your plants. If you’re wondering “why didn’t my onions grow big?,” it could be because you didn’t use enough fertilizer.
Onions are a hungry crop that need feeding for the biggest bulbs( credit: Alamy/GKSFlorapics)
For the bulb to grow and get bigger, onions do need water, but they only really need a lot of it when it’s hot and dry. When there are heat waves, giving onions more water can help stop bolting, but too much water can usually make them grow poorly. If you water a crop too much, it can get fungal or bacterial diseases. Onions can rot in the ground after just a few days of too much water.
“Plant it in soil that is moist but not soggy,” says Julia Omelchenko, a botany expert who works for the NatureID app. Water the onion frequently until the bulbs establish. Then you’ll need to scale back on watering. Make sure to increase watering when it’s hot and dry and reduce it when it gets colder.
Onions should get about an inch of water per square foot per week, but this can change depending on whether it rains or doesn’t. Check with your fingers to see how much moisture there is in the soil an inch down. Many growers use drip irrigation to focus the water down to the roots rather than spraying the leaves. It is important to check the pot’s moisture level every couple of days if you are growing onions in pots, since the soil can dry out very quickly on hot days.
In the middle of summer, when the bulbs have swollen and the leaves have turned yellow, about four weeks before the onions are ready to be picked, the crop should no longer be watered. Continuing to water after this point will impair the bulb’s storage life.
Giving onion crops the right amount of water is key( credit: Getty/Halfpoint s)
Onions regularly bolt and it is caused by the plant feeling stressed. Because it is stressed, it grows a long stem so that it can flower and make seeds. Bolting can happen when it’s hot and dry and there isn’t enough water, or when it gets cold out of the blue. A bolting onion stops bulbing because it wants to flower, which is bad for the grower because it ends up with small bulbs.
Although it’s not all bad news if your onions start to bolt, you can still harvest them. If you want to store them, though, keep in mind that onions that have bolted won’t keep well.
Jen McDonald, a certified organic gardener and co-founder of Garden Girls, advises: ‘Cut the flower off and you can either leave the onion in the ground for a few weeks longer or you can harvest it. You can also choose to save the seeds to plant the following year.’ A bolted onion is edible and can last for up to a month in the ground, though it is advisable to use them right away.
You can buy varieties that don’t bolt, and onions grown from seeds tend to bolt less often than sets. Dominique Kline says that the best way to stop bolting and keep your crop from being stressed is to do things like water it often when it’s hot outside. “Keep an eye on the forecast for your area,” she says. “During cold snaps, cover your crops to protect them from shock. During heat waves, spray your plants with cool water to protect them from the change.”
Bolting is common in periods of hot and dry weather( credit: Alamy/Marina Kovacevic)
Growing the wrong type of onions
Short day, intermediate day, and long day onions are some of the different kinds of onions you can grow. They are differentiated by the level of daylight hours the variety needs to start forming bulbs. Growers may have trouble with it because some types do better in certain USDA zones and won’t do as well if they are put in the wrong climate.
Bruce L Frasier, President of Dixondale Farms in Carrizo Springs, Texas, claims that choosing the wrong variety for your area is the ‘foremost’ issue when it comes to many people’s onion growing problems.
He explains: ‘Onions are characterized by day length requirements. When the days get to 10 to 12 hours, short day onions start to bulb. On the other hand, intermediate days need 12 to 14 hours, and long days need 14 to 16 hours.
“Planting on a short day in the north won’t make enough leaves before the bulbs start to grow, so the onions will be about the size of golf balls.” If you plant a long-day variety in the south, you’ll get big green onions that never turn into bulbs. ’.
When choosing what onions to grow, make sure to pick varieties that are best suited to your regions. Find out what USDA zone you are in to see what cultivars will do well there, or go to local farmers markets to see what kinds of plants growers there are having success with.
Onions come in short day, intermediate, and long day types( credit: Getty/Lezh)
New GENIUS Method Of Growing Onions From Seed – Mid February To Mid March Time To Start Onion Seeds
FAQ
Why are my onion seedlings not growing?
Are onions hard to grow from seed?
Why do my onion seedlings keep dying?
How long do onions take to mature from seed?
Can you grow onions from seed?
Sets are the easiest to grow and can be planted straight outside, making them a great choice for beginners. If you’re growing onions from seed, you’ll need a seedling tray located indoors, good-quality peat-free seedling compost, and something to replant them into – either larger pots and compost, or a bed in your garden.
How do you grow onions in a garden?
Weed your soil and work through compost and a general-purpose fertiliser. 3. Plant the sets with the pointy section facing up and locate them about 10-15cm apart 4. Keep the area weed free and water them during dry periods. 5. You can harvest the onions when they’re big enough to eat or the leaves have turned brown and started to wither.
Are You planting the wrong type of onions?
You may be surprised to learn that one of the most common mistakes when it comes to growing onions is planting the wrong type. This is especially true if you’re buying your seeds, sets, and transplants from an online source.
How to grow a large onion?
To grow large onions, keep the weeds out of their turf. Be careful not to disturb the onion bulb while weeding, as you’ll do this by hand. Pull weeds gently from around and between your onions. By doing this, your onions should thrive. 7. Harvest and Store