How to Grow Onion Microgreens in 5 Easy Steps
With onion microgreens, you pack that oniony goodness into a tiny little sprout! Microgreens are very easy to grow and add vitamins and minerals to your diet. Rachel Garcia will go over how to grow them yourself.
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From winter to bunching to green, there are tons of cool onion varieties. They may be different colors and have different flavors, but all have one thing in common: onions make great microgreens! Onion microgreens are low-maintenance, tasty, and the perfect new garden project.
If you haven’t tried growing microgreens yet, it’s definitely worth a shot. A microgreen, like a sprout, is a young plant that’s harvested early for its tender flavor and surplus of nutrients. Unlike sprouts though, microgreens are grown until they develop their first leaves (cotyledons), which optimizes its culinary characteristics.
Onion microgreens are one of the more unique-looking choices. These long, skinny greens hang onto their black seed husks, which gives them a polka-dotted look. The husks are edible and said to have a garlic taste. The onion microgreens themselves are savory and have a stronger onion flavor than you’d think. They taste delicious when prepared like chives or chopped green onions.
Onion microgreens are very easy to grow, but they grow slowly (you may want a faster plant if this is your first time growing microgreens). It’ll be anywhere from 12-21 days until these fresh greens are ready to harvest. Once the time comes, these onions will definitely be worth it!
Yellow Sweet Spanish Utah Bulb Onion
Yellow Sweet Spanish Utah Bulb Onion Seeds
What You’ll Need
Onion microgreens need the same materials as any microgreen to grow. Most of these can be reused so you can experiment with other microgreen types later on.
Seed
You might be wondering: don’t onions grow from bulbs, not seeds? It turns out that these plants can do either one, but seeds are the most efficient for onion microgreens – especially since we want to grow them close together. Since the seeds are so small and they’ll be densely planted in the soil, you may want to buy them in bulk. You’ll need at least half an ounce of seeds per 10×20” tray of soil.
Although seeds are the norm, you can still plant bulb sets instead for larger onions. Be aware that bulbs will not produce grass-thin microgreens as seeds do. If you want to give this a try, we recommend checking out our article on planting onions.
You can choose any onion seed you like. Seed like Texas Early Grano is tried and tested with an excellent germination rate, or you can try a red onion seed like Red Amposta, Flat of Italy, or Monastrell.
Containers
Choose containers that have drainage holes or that can have holes poked in them. You also need a cover and a container without drainage holes is ideal for this job. If you need to purchase containers, try Seed Starting Trays from the online shop.
Growing Medium
Seed-starting soil is usually the best for microgreens growing. However, onion microgreens will also grow well in coconut coir. This medium will retain moisture better than soil so you don’t have to water as often.
Grow Lights
We recommend using grow lights to get straight microgreens rather than relying on sunlight. You’ll also be able to control the amount of time the microgreens get light each day for a better result. You can get Seed Starting Grow Lights for growing microgreens indoors.
Extras
A few other basics will include a misting bottle and kitchen shears for sipping the microgreens for harvesting.
How to Grow Onion Microgreens
Onion seeds are teeny and don’t have to be soaked before planting. But, a couple of hours submerged in water may help them germinate faster, so it’s up to you. These are the steps that follow for growing these oniony greens.
Step 1: Plant
We want to grow onion microgreens like a dense mat of grass. This saves space and optimizes our harvest. To start, punch some water-drainage holes in a growing tray and fill it almost to the brim with soil. Pack the soil down and wet it with the spray bottle. We’re now ready to start planting seeds!
Spread your microgreen seeds all over the soil surface, including the corners of the tray (you may want to use a shaker bottle). The seeds should be close together. However, you have to ensure that they aren’t actually touching each other. When they grow too closely, onion seeds create the perfect habitat for fungal growth in the soil. Leave the seeds exposed instead of covering them with soil.
Step 2: Cover
After planting, give your onion seeds a good spritz of water for germination and then place the second tray directly on top of them (right side up). This creates a blackout for the onion seeds to germinate while also pressing them into the soil. You can even add up to five pounds of weight to the cover to ensure no light gets through to the seeds. After germination, when the onion microgreens start growing, they’ll collectively push up the cover and weight.
Step 3: Grow
Keep your planted seeds in the dark for at least three to four days. They likely won’t need watering during this time. When the seeds grow into seedlings and have yellow coloring, you can remove the seed cover. The sprouts may seem squished down at first, but they’ll quickly stand up (and turn green) in the light.
Place your onion microgreens directly under the grow light. We prefer artificial light for indoor microgreen growing because the shoots grow towards the light. If the trays are simply placed on a windowsill, the microgreens will grow unevenly. With a grow light, you’ll also be able to control exactly how much light the trays get each day (we recommend eight to twelve hours).
Remember how we’re trying to prevent fungus growth? Perhaps the most important precaution we can take is bottom-watering the tray. This keeps the microgreens dry and less inviting to fungi spread.
To water from the bottom, grab your second tray. Fill it with a couple of inches of water and set the growing tray inside it. Let the soil drink up the water for about ten minutes and then remove it. Repeat this watering process whenever the soil starts to dry out.
Step 4: Harvest
Onion microgreens have a larger window than most for harvesting. You’ll be able to harvest bit by bit instead of all at once (though you can certainly do just one big harvest). However, take note that the microgreen flavor will change as they mature so you don’t want to wait too long. Sometimes, the onion microgreens also dry out on the tips as they keep growing.
Begin harvesting your onion microgreens when they’re four inches tall and start leaning over (they’ll look like un-mowed grass). Using clean kitchen shears (or something similar) clip the onion microgreens in bunches at least half an inch above the soil surface.
Onions grow from the bottom of the stem instead of the top. This means we can squeeze a second harvest out of the trays. Just keep caring for the microgreens until they regrow and can be harvested again.
Step 5: Store
After the harvest, hold off on washing the onion microgreens until you’re about to use them. As mentioned earlier, you can keep the seed husks on or remove them from the onions. Whichever you choose, each delicious green will provide an excellent, no-hassle, onion flavor (they won’t even make you cry when you chop them!).
Keep your microgreens, onion or other, in a sealed container in the fridge. They should stay fresh for up to a week – especially if you put a paper towel in the bag to absorb extra water.
