Guide: Growing Corn Microgreens

A quick and dirty guide on how to go from corn to shoots

A simple Step-by-step guide to growing Corn Microgreens indoors. We will take a a look at the process first and at the end we will finish off with more practical details on tray, corn, soil and light to use. Got questions? Don’t be shy, use the comment section 😉

Step 1 – Soaking seeds

Take your corn and soak them. I’ve tried soaking the corn anywhere from 4 to 24 hours and even though the longer you soak the seeds seem to help the germination, the difference isn’t large enough for me to wait longer than 4 hours. The reason why you’d like to soak the seeds are because there’s a thin film on the corn that protects it, by soaking it we loosen up that film and allow for a more nice, even germination.

Scientists are still trying to figure out if using a red bowl helps the soaking process, but use a different color at your own risk.

Step 2Add soil to trays, seed the soil. Add water.

How much soil to use? I prefer 2.5 centimetres (1 inch). The more soil you have, the less you need to fiddle around with watering since more soil means more water that can be absorbed at once. I use about 200 grams of seeds per tray, but if you don’t use the same dimension on trays as me that number is fairly irrelevant. A rule of thumb I’m using is seeding the trays until it seems like its even enough – In my experience you don’t need to cover every single inch with a seed, look for good enough not perfect. I’ve done this so many times now that filling trays takes under a minute per tray and goes super quick. Once the seeding is done, I like to spray the trays soaking wet (with water) so I don’t need to water for the 3 days they are stacked on top of each other. Speaking of:

Step 3 – Stacking for 3 days and “Blackout” for 4 days.

I use an extra tray, a piece of cut out cardboard and some weights, while many professional growers use a cement block.

By putting the trays on top of each other and adding some weight to the top you create a gentle way to push the seeds into the soil, making the soil contact consistent. This, in turn, makes the germination very even and ensures maximum harvest for minimal effort in the end.

It is preferable if you can shelter the trays from as much light as possible since this will stimulate them to try and seek out light by growing faster, just as if they were growing in the wild. Me, Curtis Stone, Kevin from Epic Gardening and Chris Thoreau all do this step slightly differently and we all have great harvests from our separate methods. I don’t think there is a “best method” here, I encourage you to experiment and find your favorite.

Check in every now and then to make sure everything is going fine under pressure for your seeds, but keep it pressing and squeezing together for 3 days.

After three days its time to unstack the trays and allow the growing seedlings to enter a blackout period, which in my case is 4 days long. I use an extra tray lid to “shield”the growing seedlings from the light, as illustrated by the photo to the right. Its probably time to give the poor guys some more water by now too, especially if you use as little soil as I am. I’m using the bottom tray to water the corn from here on out because I’m paranoid about mold – I’ve not grown any mold with my microgreen corns yet, so I think I’m on to something.

The blackout period is used to trick your seedlings they are still under ground and need to grow more to reach the sun (or grow light in our case).

Step 4 – Last stretch and harvest

You can harvest the microgreens after 4 days of blackout, like On the Grow did during their beta testing, and if you do that you get a sweeter microgreen crop that has a quite unique yellow color. I am looking for a microgreen that is a bit more grassy in the taste so after the blackout stage I let the shoots absorb 1.5-2 days worth of light. You can grab a snack every now and then and see how you like the greens, what you prefer might not be the same as what I prefer 🙂

Equipment Suggestions

I like my sturdy grow trays from Elho, a Dutch producer, but it seems the ones I’m using hasn’t been restocked yet so might be hard (impossible?) to get hold of. A good alternative is Bootstrap Farmers microgreen trays – High quality and not as flimsy to handle (read: easy to break when washing) as other brands.

Not using those personally, but have a friend that use them to good effect. There is cheaper alternatives, but you want quality trays that can take a punch or two without becoming useless. With washing, replanting, stacking, and so on you put your trays under a lot of stress, more than you think! Another important thing to consider is the dimensions of your trays: I picked trays first and picked out shelves that fit them, there were more options for shelves than trays for me. Something to have in the back of your mind.

What is non negotiable though, if you want a flexible tray system that you can use for a lot of different things, is a bottom tray. This will allow you to water from the bottom, saving you a lot of time. Plus, it lowers risk of molds and other nasty things in your top tray. I can flip over the bottom trays and they become a way to blackout crops with too. If you can, test the ones you want to purchase and check if you can perhaps save a bit on purchases to use the trays not currently in use as blackout trays.

As for grow lights, in my experience and observation from other growers, it seems there isn’t a simple answer to what you should get. There is one key thing though: You want full spectrum light to make sure you can grow the widest range of stuff with the lights. It will save you time and money in the long run. But, from there its just finding lights that fits your space and what looks good. Sunlikes grow lights are the best bang-for-your-buck there is when it comes to lights, and the life length is stunning. You could have one on for 12 hours a day for 5 years straight before you have to switch it out.


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