Dirty Business: Microgreens

This is for the people who either can’t grow a garden outside, or for the people who want fresh produce even during the non-growing months.  Microgreens are quick, cheap, relatively easy to grow and highly nutrient-dense.  There are a bewildering variety of microgreens available for growing—everything from lettuces to vegetables to more exotic types like amaranth or sorrel.  They can also be grown either with or without soil, depending on the type of green.  I’m lazy, so I only grow greens which don’t require soil (hydroponically) and that’s what I’ll be showing you today.

To grow microgreens hydroponically, you’ll need the following equipment:

Growing Tray

Cover Tray

Growing Media

Grow Light(s)

Seeds

Spray Bottle

Your growing trays can be big or small, depending on your needs.  Our trays are 10”x20” and we splurged on sturdier plastic trays.  The more commonly found black trays are thin and prone to cracking and leaking, but they are excellent for use as covers.

Growing media comes in a number of different types and sold either in precut sheets or in large rolls.  We get the rolls because it’s cheaper per sheet to buy them that way.

You can get pretty much any variety of grow light that you like, provided that your light is large enough to shed light evenly over the whole tray at a fairly close distance—no more than eight inches from the tray—so using small lights that are typically used at higher distances for starting vegetable plants won’t work because you’ll have light and dark sections of the tray.  We decided to splurge on an aluminum rack so we could grow multiple sets of greens at once, and it has paid off for us over time.

You can get seeds from almost anywhere.  For our part, we get our seeds from True Leaf Market.  They have a wide variety of seed types and supplies.  Pretty much a one-stop shop for microgreens.  They also have a very helpful set of how-to videos.  So, if you want more detail than is posted here—or you’re interested in using the soil method, their site is a good resource.

Before you start your seeds, you’ll want to test your water for its pH level.  While microgreens will grow in drinking water from almost anywhere, they will respond better to water that is pH balanced between 5.5 and 6.5.  You can use a basic litmus paper test on your water to see what the pH is and then adjust it from there.  Our water is a little too alkaline, so we add ½ teaspoon of lemon juice per gallon of water to nudge it down to the ideal range.  If your water is too acid, then you’ll probably want to use a pH Up liquid, as there isn’t really anything else that will do the trick.

For hydroponic growing, it’s also helpful to add a little nutrient mix to the water.  We add about a teaspoon per gallon of this stuff called Floragrow.  It’s not required, but we’ve found that the greens tend to respond better.

Because we grow a lot of microgreens at one time, we tend to prep ahead with a number of gallon jugs of pH-balanced and nutrient enhanced water which are ready to go.

So, once your water is ready, the rest is pretty straightforward.  Start by placing a sheet of growing media in the tray and soak with water.  For a 10”x20” tray we use two cups of water, tilting the tray this way and that to make sure the water gets everywhere.  Then, flip the media over and tilt the tray again.  At that point, you can use a spray bottle filled with your prepared water to soak any remaining dry patches, or you can just use your fingers to pat the media down to get it wet.

Once the media is good and wet, sprinkle the seeds evenly over the media.  Eventually you’ll figure out how dense the spread should be for your greens.  This is a tray of broccoli greens:

Use the spray bottle to get the seeds good and wet, then spray the inside of a black cover tray and place upside down over the top of the seed tray which will create a good amount of humidity and darkness.  The seeds need darkness to encourage germination.  What we’re doing here is essentially mimicking an underground environment for the seeds.

Then, each day over the next few days, lift the lid and spray the seeds and the inside of the lid and cover again.  The seeds usually germinate within two or three days.  After about four or five days (depending on the type of green), they will have rooted and begun to grow upward.

When the greens are at this stage, you’ll want to then flip the lid over, spray the bottom of the lid and place it down on top of the sprouts.  This, again, is to mimic an underground environment where the sprouts have to struggle to break through the earth.  They need a little weight to fight against to become stronger and avoid getting thin and leggy.

At this stage, instead of wetting the sprouts with the spray bottle, feel underneath the growing media to determine how wet or dry it is.  Then simply lift up a corner of the media and pour an appropriate amount of prepared water in the tray, and tilt the tray around so that the water is evenly distributed.  Some greens are thirstier than others, so you’ll get the knack for how much is enough as you go along.  If your greens suddenly lay down and die in the whole tray, then you’ve watered them too little.  But, have no fear, usually watering them again will help them recover if they haven’t been dry for too long.  If a small patch of dead greens appears and starts to spread, then you are watering them too much.  The only remedy for this is to back off on the amount of water until the dead patch stops spreading.

After two or three days more, the greens should be almost to the level of the sides of the growing tray.  At that point, remove the black cover and turn on the grow light—again taking care to keep the light fairly close, no more than 8 inches away. 

Continue checking and watering on a daily basis, or as needed, for another few days until the greens have well-established leaves on top and are green and lush like the header image.

To harvest, simply take a pair of scissors and give them a haircut as close as you can to the growing media.  We don’t harvest the entire tray all at once, but instead cut out a few rows at a time for our salads with dinner.  If the greens get a little too large, or start to get a little wet rot near the roots, then take them all out and keep in a breathable container in the fridge.

After the initial investment in equipment (which, depending on your setup, can either be considerable, or just a few bucks), the cost of a tray of greens is literal pennies to grow.  We haven’t bought lettuce from the store in years.