How to grow onion microgreens and doing it perfectly is super simple. In this guide I take you by the hand to show you step-by-step how to go about growing your own onion microgreens at home.
The best part about what I will show you here is that it is applicable when growing microgreens of a variety of types such as cabbage, lettuce, and radish among many others. You may also see my general how to grow microgreens indoors guide here.
In this method, we will be growing our onion microgreens using soil. Microgreens such as sunflower can be grown without any soil at all as I show how to do this here. Onion microgreens, however, do well when grown in soil.
But what are onion microgreens? Onion microgreens are essentially germinated onion seeds that are allowed to grow to a certain stage, which is not too far along to maturity. They are then harvested for use in salads and preparation of all manner of recipes. As one could imagine, onion microgreens bring amazing flavor and taste to salads and other microgreens when mixed together.
There are over a dozen onion varieties under the scientific name Allium cepa. These varieties include Ailsa Craig, Italian Torpedo and Red Burgundy among others. You are free to use any variety you fancy. It should be just fine.
In case you have a general interest in growing all types of onions, I also invite you to have a look at this step-by-step guide that I put together on how to grow mature onion from kitchen scraps. Many people throw away onion scraps, but you could regrow these into full mature onions if you wanted to. It is also fun to do especially with children.
What you will need to grow onion microgreens
You will need a few things to successfully grow your onion microgreens. Here is a list with some links to a good source of the materials in case you first need to purchase any.
- Microgreens trays (supplier)
- Grow lights (supplier)
- Soil sifter (supplier)
- Soil
- Onion seeds (supplier)
- Watering spray (supplier)
- Water for watering
1. Prepare your growing soil
Our first step is to prepare the soil. Many people think that microgreens need some super special soil type to grow. Your native garden soil should do just fine as microgreens rely on nutrients in the seed to thrive in the first several days of life.
Unless you prefer it that way, you can get potting soil and what not to grow your microgreens but good old garden soil will do just fine. Remove any debris or particles from the soil by sifting the soil. I find that sifted fine soil also makes it much easier for the microgreens seeds to germinate. Use a sifter to sift your soil.
2. Fill microgreens growing tray with the sifted soil
Next, grab your microgreens growing tray and fill it with your prepared soil. Your tray should have draining holes underneath.
Although, many people are now using commercially sold microgreens trays such as these ones, any good container will do. In fact, I have grown microgreens in repurposed grocery punnets which once contained tomatoes, onions and so on.
So do not crack your head a great deal on what container to use. Any container not too shallow yet not too deep will do just fine. But of course if you so wish, you may invest in a commercial quality long term reusable trays .
3. Thoroughly water the soil in the tray
Our next step is to thoroughly water the soil in the tray. For this, use a watering spray that produces a fine spray to avoid disturbing the soil in the tray. The soil should be well soaked after the watering as this will be our only watering episode until the onion seeds germinate. You will know the soil is well soaked when water starts draining through the bottom holes of the tray.
4. Plant your onion microgreens seeds in the tray with watered soil
Now that the watered soil is now sitting in your tray or microgreens growing container, it is time to plant the seeds. Take your onion seeds and evenly spread them all across the tray. Since we are growing microgreens, ensure that the seeds are densely but evenly spread. Ensure every corner of your tray has some seed.
Note that we had to water the soil first before planting the seeds to avoid disturbing the seeds by watering dry soil. This was also in preparation of the next step which we now turn to.
5. Gently press the onion microgreens seeds into the wet soil
Using your open palm, gently press the seeds into the soil. We want the seeds to come into full contact with soil and not buried in the soil hence the press is to be gentle. We will not be covering the seeds with any soil so the press will cause enough contact with soil to stimulate germination of the seeds.
6. Cover the planted tray and store away
The next step is to cover the tray and putting it away in a dark cool place. The following is optional but I find it useful. You may put a board or a fitting card over the tray on top of the seeds to create some kind of weight. This increases the speed and quality of germination. So put a board or card and a weight like a stone on top before putting away the tray.
Let the tray sit in a cool dark place for the next two to three days. At about day three you can check to see if your seeds are germinating.
7. Move tray to a location with light
Once the microgreens have germinated covering about 85-90% of the tray, it is time to move the tray out of the dark onto a location with light and free flowing air. This is the time to place the tray under artificial light as emitted by fluorescent lamps. There are now a variety of grow lights available to use for this purpose. You may have a look at some of them here that I recommend.
Avoid putting the tray in direct sunlight. Microgreens will not do well under these conditions. You will need soft light which enhances growth in an upward trajectory that is aesthetically pleasing. Soft light is also important in ensuring the microgreens have good flavor.
8. Water the growing onion microgreens
Once you have moved the onion microgreens onto to a location with light and good air circulation, it is also time to water them for the first time. Microgreens are prone to mold. One of the ways mold develops quickly is when the microgreens are kept moist on the stems and leaves. This comes down to how you water them.
To reduce risk of mold, avoid watering the microgreens by spraying water directly. Instead, sit the tray in a bigger container filled with water such that water percolates from the bottom through the draining holes into the tray. I show this simple method of watering microgreens here.
Keep watering the onion microgreens every other day until harvest. The trick is to ensure that the soil is not soggy but just moist all the time.
9. Harvesting your onion microgreens
Unlike some other types of microgreens, onion microgreens take a bit more time to grow to the point of harvest. Regardless, the wait is worthwhile as the flavor to de delivered by these microgreens in your salads is amazing. At about 10-12 days your onion microgreens should be ready for harvest.
How to tell when the microgreens are ready for harvest is by observing their stature in the tray. When you notice them start falling over, this is a good sign they are ready for harvest.
Take a kitchen scissors and cut the onion microgreens off just above the soil. Do not uproot the microgreens out of the soil. If you do this you rob yourself of a potential second and even third harvest.
After cutting them, the remaining stumps will regrow and fill the tray once more although this time around the yield may be lower. The point, however, is that it is possible to harvest onion microgreens more than once.
Before consumption, chop off the ends of the microgreens which still have the seed shells attached.
10. How to store your harvested onion microgreens
Once you have harvested your onion microgreens, put in a container or zip-log bag and store in the fridge until needed. As per usual, microgreens are freshest and with best flavor punch when consumed closest to the time of harvest. The further away it gets from the day they were harvested, the less fresh they become.
So this is how to grow onion microgreens easy. Enjoy your journey, I suspect you will be hooked!
