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.