The Mother of Invention

They say necessity is the mother of invention, but I say so is frugalness.  Over the last couple weeks I have ramped up production with an additional weekly restaurant account and increased sales at the farm market.  As a result, I have found myself with more trays than I have lights for.  Since I grow to order, that is a very good thing.  However, I’m not quite ready to invest in a third set of shelves and lights.

I was contemplating this dilemma when I realized I wasn’t using the top shelves.  I was storing random stuff up there, but between my two racks that was potentially room to light 8 more trays.

My first thought was to hang lights from the ceiling.  That seemed a bit precarious.  In the meantime I posted a photo on Instagram of my racks running at full capacity and someone said he had used PVC to hang lights for the top shelf.  Ingenious!

I ordered 4 more lights from Amazon.  When those showed up I ran to Ace and eyeballed which size PVC would fit the posts.  Of course my husband was out of town with the truck, so I had to have it cut in half to fit in my car.  Four elbows for each rack, a few cuts on the chop saw, and voila!  Room for 8 more trays.


Fancy PVC light holder

Hopefully I will need to bite the bullet and outfit a third rack to accommodate more business soon, but for now this will do.

Damping off

Damping off: the enemy of microgreens

Microgreens are delicate.  When growing something to full-size you have a bit of play.  You can usually make some mistakes and still end up with good results.  Not true with microgreens.  When growing less than two weeks and in cramped corners there is not a lot of room for error.  Having the right temperature, humidity, and water are critical.  So is having sterile soil.

I have been battling damping off in my kale trays for about a month now.  Damping off is the result of a fungal disease and shows up as smooshy seedlings.

When I brush my hands over the seedlings, all I should see is stems.  If I see little smooshy bits at the bottom (like in the photo above), my tray has been contaminated for one reason or another. Damping off spreads so once I notice it, the best action is usually to just dump the tray.  Not good if I am trying to make a profit.

I got a second dehumidifier going, closed all the vents in the basement so it would be a little warmer, and became diligent about bottom-watering.  Nothing seemed to help.

When I opened my next bag of soil I noticed a lot of mold on the inside of the bag.  That’s when I had my lightbulb moment and realized it was my soil.  The last time I bought soil I had thought they were heavier than usual.  They must have been stored outside and had small holes in the bags which let in water and mold spores.

I decided to order a bag of Promix HP on Amazon.  My thinking was that Amazon would most likely be storing everything in a warehouse, not outside.  Promix HP is a little more expensive than the All-Purpose Promix I have been using, but worth it if I would no longer have to dump trays.

The results are in and they are good!  The new soil is much lighter, doesn’t stay damp as long (important for microgreens to not stay wet 100% of the time), and best of all it magically shows up at my house.  And no more damping off!  If I could just get the FedEx guy to carry the 65 pound bag to my basement, I’d be golden.

What to do with all that soil?

Let’s face it.  Buying brand new potting soil for every tray of microgreens isn’t especially sustainable.  Or cheap when each bag of soil is $20.  However, it would be kind of difficult to screen out all the roots, hulls, and stems that end up in the soil after harvest.  Not to mention, if there was any mold present, it would be exasperated by reusing the soil unless it was sanitized.  And I’m not about to start throwing piles of potting soil in my oven.  Luckily I have other uses for good soil.

I have found a solution that I can live with for now.  Jason built me a bin out of t-posts and pallets with a removable door.  I get one of my teenagers to carry my containers of used soil out to the bin.  Then I let it sit.  I’m not necessarily composting because I am not adding layers and paying attention to how hot it gets, but I want to let the majority of the green matter rot so that I am left with mostly just potting soil again.

Microgreen trays dumped into my bin to sit a while

Next, I move the soil to our new greenhouse to build up our beds.  The plan is to add layers of my spent potting soil and compost, and eventually we will have soil that is the envy of everyone who gazes on its glory.  Look for specialty greens like arugula and mustard this fall as our first crop with this reused soil.

Starting to build the beds in our new greenhouse

Eventually I would like to be able to reuse this soil for the microgreens.  It is going to take more careful planning and a dedicated area to carefully compost and sift.  In fact, inspired by mom’s grant for Red Brick Farm’s new greenhouse, I am starting to look at grants to possibly help fund a more sustainable solution for me.


After the trays have sat stacked for a few days, it is time to uncover them and put them under the lights.  I don’t wait a specific number of days.  Every morning I check all my stacked trays and uncover any that are ready for light.  There is some wiggle room for how many days you wait.  However, if you unstack too early the newly germinated seeds dry out and die. If you wait too long the soil ends up molding because there isn’t any airflow between the trays.


Kale ready to be uncovered


Radish ready to be uncovered

You will notice in both of these examples the leaves are yellow.  Because they have been stacked they haven’t gotten any light – after a day in the light they look significantly different and the leaves are green.  Once I uncover the tray, I put it under my lights and give it a good watering.  For most varieties, this is the only time I water from the top.  These are newly germinated seeds, and as such they dry out easily.  I give them a good saturation making sure to water the entire tray lightly.

I grow with two trays – the soil and seeds are in a tray with holes which sits in a tray without holes.  Every morning I rotate all the trays on the racks, then check in between the two trays to see if they need watered.  If I pick up the top tray and there is some water in the bottom tray, it waits until the next day.  If not I put enough water water in to almost cover the channels in the bottom of the tray.


Channels in tray

That’s about it for watering.  Some varieties that grow super fast, like radish and sunflower, I water from the top occasionally because they dry out easily.  The rest I only water from the bottom because I found out the hard way they get damping off when watered from the top.

Let’s get planting

I thought I would spend a few posts talking through my process.  At a high level, it is simply: plant, water, harvest.  But there is a little more to it than that.  Today I will cover planting.

Since my growing room is in my basement, the first step is to try to con one of my teenage boys to carry the pro-mix bale to the basement.  If that doesn’t work I put on my big girl pants and carry it down myself.


The pro-mix is compressed so it can’t be used straight out of the bag.  I put some in a plastic bin and get to work breaking it up as fine as I can.  I used to screen it but lately I have ditched that effort because it seems I am always short on time.  Next I add some water so that it is damp but not soggy.


Next I lay out the trays and fill them with soil.  I am the queen of using what I’ve got, so I use an old concrete mixing cup.  I’ve found that 4 cups full fills the trays nicely.


I spread the soil out with my hands and then use the “smoosher” that my husband made for me.  It is important to have the soil compact and as flat as possible so that germination will be even and the microgreens will be fairly consistent in height.  Otherwise you have a harvesting headache.


Next it is time for seeds!  I used to measure my seeds by weight but found that was taking a really long time.  Now I use a measuring spoon (or cup for sunflowers and peas).  I use about 2 1/2 tablespoons for seeds like kale and cabbage, and 3 tablespoons for bigger seeds like radish.


The goal is to have good even coverage.  You don’t want clumps of seeds – if they are too thick they will rot as they get bigger.


The last step is to stack and weight (and wait).  I stack all varieties.  About 5 trays high, with a brick or two on top.  This helps aid soil contact with the seeds which increases germination.  The seeds also don’t dry out this way and it drives the roots down into the soil so you have strong healthy greens.  I peek at everything each morning to see if they are ready to be uncovered – usually they are uncovered after several days and introduced to the light.


Sprout or microgreen?

I often hear the terms “sprout” and “microgreen” used interchangeably.  In reality, the two are very different.  I thought this first blog post would be a great place to clear things up.

Sprouts take 7 days or less to produce.  Germinated in water, usually in a jar or tray, the seeds are kept damp and rinsed periodically.  Since they are grown for such a short time, very little light is needed.  The entire sprout and root are eaten.  Have you ever had alfalfa sprouts or bean sprouts?  If your answer is yes then you’ve eaten sprouts.

Microgreens (or shoots) are grown slightly longer.  Usually 7-14 days.  The seeds are planted in a growing medium (unless grown hydroponically).  This can be potting mix, felt, or even a paper towel.  Once the seeds germinate they are given light and grown until they are the desired size and height.  Microgreens are harvested at the cotyledon stage.  Cotyledons are the first two leaves produced by the seed.  To harvest, the leaves and stems are cut off (I use scissors) and the bottom (the seed and roots) is discarded.

After the microgreen stage you reach the baby stage.  Let’s consider baby spinach for instance.  Have you ever noticed those weird long skinny leaves in a bag of baby spinach?  Those are the cotyledons.  After those cotyledons are mature, the first true leaves start to form.  These are the leaves you eat when you buy baby spinach.  In the same way, you could have baby kale, lettuce, mustard greens, etc.


Spinach with cotyledon and first true leaves