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For many years, I would just buy the same ol’ sets from the farm store to start our onions in the ground. But, the last couple of years, I’ve started our onions from seed. They’re not really difficult to start from seed, but it’s an involved process. A process I will continue to do because….
If I start onions from seed, I can select the varieties we want to grow. Instead of whatever variety is available at the farm store. Which is generally eloquently labeled white or red. Wow… decisions, decisions.
Another fun perk about starting onions from seed is you get to play in the dirt starting in February. Which, to me, is fun. It brightens my day any time I get to play in the dirt. Especially when it’s cold out and everything is still covered in snow… if we ever get any snow.
I usually just pick one variety and stick to it, but a great idea is to pick multiple varieties that mature at different rates. That way, you don’t have a huge harvest all coming in at once, but you can start everything at the same time in the dark, cold days of early February.
How to Start Onions from Seed
Presprout Your Seedlings
I like to presprout things. Why? Well, I know what germinated and what didn’t before it goes into the soil. Another reason is, the kids find it fun to do as a little homeschool project. Maybe I’m weird? I don’t care. I think watching the plant come out of the seed is neat. I like watching it grow instead of it being buried beneath the soil sometimes waiting on it to pop up.
Note, though, you do not have to presprout (which is called chitting). You can just stick them in moist seed starting mix and cover them lightly with about an 1/8″ of seed starter. We find it too entertaining to skip this part, so we do it every year.
- Place your onion seedlings on a damp paper towel (not drenched, not barely wet) and then place them in a plastic bag and zip it. We stick ours in the kitchen windowsill, though they do not require light to sprout. If you don’t have a bright place, that’s okay.
- Keep an eye on your seeds for the next few days. Some varieties take longer than others to sprout. But, once you see a sprout coming out of the seed, wait a day and then you’ll transplant the seedling to some starter mix.
Transplant Your Seedlings
Onions will be in starting containers for a long while, and they are heavy feeders. I usually use containers we get fruit in from the farmers market. I’ve heard of people using strawberry containers as well. You don’t want anything huge, it needs to drain easily, and you’ll just set whatever you use on a plastic tray or some other sort of container for the water that leaks out of the bottom of your containers.
- Fill your containers with organic seed starting mix about 3/4ths full and tamp it down. Moisten the soil. Don’t drench it, but it should be wet. I always wet it down before I plant anything, even seeds. It makes it easier. Albeit, a little messy. Sprinkle just a little bit more starter mix on top of the tamped down starting mix.
- Place the seedling root down into the soil, gently. Note: onion seedlings will sprout with the seed capped on the top of the seedling, not on the bottom. So, don’t stick the black seed into the dirt, stick the opposite end in. If they don’t stand up or are covered up with soil, it’s okay. They’ll make it through in a couple of days. Plant no more than 4 for every square inch of space. You’ll thank me later.
- Put just a bit more seed starter mix on top of the seedlings. Place them under a grow lights or in a very bright, south-facing window. They will need at least 12 hours of light a day.
Maintaining Your Seedlings
- Keep the soil moist, but not drenched. Onions can be forgiving, but you run the risk of dampening off disease if you overwater.
- Once your onions have been growing a little bit, you’ll notice they begin drooping. So, you’ll give them a little trim. Just use a pair of scissors and keep the tops around 2-3 inches high. Keep them trimmed up and they’ll grow great root systems. You can use the greens to cook with, don’t waste them.
- Since onions are nutrient hogs, they will need fertilized. I use fish emulsion (which does smell, I’ll warn you now, but it will go away). Compost tea is another option.
Harden them Off
Don’t forget that even though onions are a cold-hardy crop, they still need hardened off. You’ll want to begin hardening them off about a month before your last frost date. Here in zone 5b, that’s supposedly May 1. So, in April I’ll begin hardening them off. If you aren’t sure, you can find your last frost date here.
- For the first week or so, I put a fan on them lightly for a few hours a day. It makes the tops stiffer.
- About 2-3 weeks before I plan on taking them out to transplant, I’ll start taking them outside. The first few days they need a sheltered location out of the direct wind and sunlight.
- After the first few days, take them out during the warmest part of the day for a few hours the first day and increase that time until they are outside overnight.
- Once they’ve been acclimated to the outdoors for a constant 24 hour period, they can be transplanted into the garden.
Transplant Into The Garden
Yay! It’s time to get them in the dirt where they can finish growing out and you can enjoy the fruits of your labor. You can absolutely harvest the greens, or just let them grow until they’re mature.
- After you’ve hardened off your seedlings, you’ll want to give the tops one more good trim. This is where you’ll thank me for not allowing you to throw all of your seeds in the soil with abandon. There’s a method to the time consuming madness…. If you planted too many seeds/seedlings together within a square inch, you’ll have a ridiculous tangled mess and break the roots off trying to get them separated.
- If you’re mulching the garden to help control weeds, do it before you plant. It will make your live a million times easier… ask me how I know. It really helps keep the weeds at bay if you do choose to mulch around them. Onions do not like weeds. And it’s a bear to harvest them if the weeds took hold.
- You’ll want to carefully remove the seedlings from your container by gently squeezing it to loosen the soil up a bit. Just like you do with any other starts or the flowers from the garden center.
- Separate your seedlings gently, and plant 2 to a hole, or don’t. I choose to put two in a hole and harvest one earlier than the other. It works really well and takes up less space. This is great for us because on an acre, we are limited on such things.
- I use a dandelion weeder to plant my onion seedlings. I know… weird. But, it’s the perfect size, it moves just enough dirt out of the way. I have never used it for its intended purpose. I like dandelions.
- Use whatever tool you have available to make a small “hole” and push the dirt out of the way. Plop the two seedlings (or one if that’s what you choose) into the hole and gently put the soil back around it. Don’t tamp it down. Just place it back around the hole. It’ll be fine.
How to Grow & Harvest Onions
The hardest part is over, really. It’s pretty easy to maintain the plants once they’re outside in the ground.
- Keep the soil evenly moist and water regularly, but do not overwater.
- Continue fertilizing them every month or so with fish emulsion or compost tea.
- Once the tops begin to die off, stop watering. If you are using the onions fresh, you may harvest them at any point during the growing season. Otherwise, once the tops die off, bend all of the leaves to the ground, uncover the top 2/3rds of the bulb for a day or two and harvest on a dry day. Cure them and put up for storage.
Onions are fairly easy to grow, and I love the ability to choose whatever varieties I want and test them out. Some mature faster than others so I can kind of stagger the season a bit, and they’re fun to cure and delicious to use. Just one step closer to that self-sufficient homestead!
Other Growing Guides You’ll Love:
- Complete Guide to Growing Sugar Snap Peas
- 7 Steps to Grow Awesome Tomatoes
- How to Start Seeds Indoors
- 8 Vegetables You Should Start Indoors
Do you have a favorite onion variety? Share in the comments below or join the conversation on Facebook or Instagram!