Onions are very sturdy vegetables. I would say they’re almost indestructible. Their roots are wiry and strong, built to withstand drought, overwatering, cold, and all kinds of environmental stressors.
Growing onions from seed may take a long time, but it’s worth it because it’s so easy. These little seedlings will survive neglect or overwatering, so they’re perfect for beginner gardeners. However, some gardeners panic when growing onion seedlings for the first time, because they have a tendency to flop over.
It’s normal for onion seedlings to fall over at some point, especially when they reach a size where they can no longer support themselves. But size isn’t the only reason why onion seedlings look a little droopy. You could be dealing with underwatering or overwatering, as well as too much heat.
In this article, you’re going to learn about some issues you might have with onion seedlings, what to do to fix them (if anything), when it’s time to transplant, and why should you even bother with growing onions from seed in the first place.
Growing onions from seed – issues with onion seedlings
If you’re growing onion seedlings for the first time, they’re like nothing you’ve ever grown before. They spring from the soil like blades of grass – when emerging, both ends of the seedling are stuck underneath soil level, and that’s perfectly normal.
As the onion seedlings emerge, they straighten out into a single narrow leaf pointing up. Often, the black seed husk is stuck to the top – it’s best to leave it for a while since you risk pulling the seedling out of the soil altogether if you’re not careful.
You may notice shallow, exposed roots on some of the seedlings. This is because some onion seeds were planted too close to the soil’s surface. But don’t worry, they’ll soon send strong roots below if you don’t mess with them or try to rearrange them.
Once they grow for a week or two, you may start noticing a few issues with your onion seedlings:
- They may start to fall over
- Their tops may start to wilt
- As they grow, the base leaves will start to wilt and brown
These are all normal with onion seedlings, even the base leaves drying out. The first leaves on onion seedlings are much like cotyledons on other plants, and it’s natural for them to wilt since they’ve fulfilled their purpose.
If you’re interested in why leaves are turning yellow and wilting on some of your other seedlings, check this article I wrote on the subject.
What causes onion seedlings to fall over?
Onion seedlings generally start to fall over because of two main reasons:
- Underwatering, combined with excessive warmth
- Size – they’re getting too big
Young seedlings that are just a couple of weeks old will often droop if you’ve failed to water them on time. You’ll notice that the soil is dry and light brown and that the trays are light. It can also get pretty warm underneath the grow lights, so if you’re growing them indoors, make sure to check the temperature.
Young onion seedlings will quickly get dehydrated, especially when grown in small modules that don’t hold on to a lot of water. But the good news is they recover just as fast. Start watering them from below and they should spring back in a matter of hours – if they do, you’ll know for sure that underwatering was to blame.
- Tip: Choose seedling trays large enough to hold the onions’ roots for 4-6 weeks – this is the size I recommend.
If you’re new to watering seedlings, be sure to check this guide on the best ways to water your young plants.
As onion seedlings get older, they also get longer and grow more leaves. It’s normal for the first leaves to die out, and even for the tips of older leaves to brown a little. The taller they get, the harder it is to support their own weight, so they tend to bend from the middle and flop over.
This is when you can either choose to give them a haircut or leave them as they are until it’s time to transplant. There’s no right or wrong way to do it, I’ve grown onions both ways, and even if my seedlings looked a little droopy and sad, they still turned into beautiful bulbs.
Should you trim your onion seedlings?
Some gardeners choose to trim their onion seedlings as soon as they’re starting to fall over and continue to trim them regularly.
There are no hard and fast rules on how to trim your onion seedlings. You can go as low as one inch from the soil, or stay on the conservative side and trim the top 2 inches off.
Just remember that you’re not harming them by doing this. Trimming the tops of onions, whether it’s in their infancy or topping adult onions, signals their roots to grow stronger and send more growth. Some gardeners swear by this method and claim it leads to more growth rings and bigger onions as a result.
You can do the same with leeks if they’re growing too tall since they’re so similar to onion seedlings when they’re young.
Also, don’t toss your onion tops away. You can use them in your kitchen as a topping and enhance your dishes with a delicate onion flavor.
- Tip: Invest in a good pair of Teflon trimming scissors. Not only will they remain rust-free, but you can also use them for harvesting all kinds of leaves and pruning tomato suckers.
When is it time to transplant onion seedlings?
When onion seedlings are about 5 to 6 inches tall and have developed three leaves, you have two options:
- You can transplant them to bigger, deeper pots and allow their roots to develop. They’ll start growing upright and thicken their leaves, and you can continue to trim them until mid-spring, when it’s time to move them outside.
- You can transplant them directly outside when they’ve formed three leaves. If you do this as soon as the weather allows it (early to mid-March), make sure to protect your seedlings from cold nights with horticultural fleece. They will still flop over and look a little sad at first, but they’ll soon send new growth.
Whichever option you decide to go with, make sure to harden off your seedlings properly, to shield them from transplant shock. Young onion seedlings will survive the cold, even if they look young and fragile, but getting them accustomed to outdoor temperatures will greatly increase your chances of success.
You can also opt for multi sowing your onions. Drop 3-4 seeds in a module for growing bulbing onions and up to 8 seeds per module for growing bunching onions. Onion bulbs will push each other apart, and while you won’t be growing giant onions with this method, you’ll triple your harvest in the same amount of space.
Planting onions from seed doesn’t take a lot of practice. Most experts agree that growing onions from seed gives you more variety and bigger bulbs that store better, so it’s a no-brainer to choose to grow them this way.
The only downside is that it does take a lot of time – you have to start 8-10 weeks before the date you transplant them outside. That’s quite a commitment to take care of onion seedlings.
If you want more options, you can find more about growing onions from seed, sets and seedlings in this article, while this post will teach you how to choose between short, intermmediate or long-day onions.
Good luck with your onions this year, and happy gardening!