If you’ve tried growing multiple flats of microgreens before, then there’s a good chance that you’ve probably encountered the issue of having your crops stuck to the bottom of the flat stacked on top of it.
Well, if you’ve tried a couple of fixes, and you have yet to find a method that does the trick, then you’re in luck because in a video released by Paperpot Co., Urban Farmer Curtis Stone shares a couple of fixes to that problem.
The Paperpot Germination Tray
The Paperpot Germination Trays are durable flats that are just a little bit bigger than the usual 10×20” trays many microgreen growers use. Measuring about 24 1/16” in length, 12” in width, and 1 3/8, these trays have holes at the bottom to allow even drainage.
One thing that Curtis noticed when he first started growing microgreens in the Paperpot trays is that because the trays have holes at the bottom and he stacks them in fours, the growing microgreen crops would tend to grow into the holes of the tray on top of them, which would then make a mess when it comes time to unstacking them.
Fix #1: Timing
After growing flat after flat of microgreens in Paperpot trays, one of the fixes Curtis found is getting the timing right. Uncovering the trays at just the right time will prevent any of the crops from growing into the holes above them. And while the timing still depends on the kind of crop being grown, Curtis usually uncovers the flats 3-4 days after seeding.
So for example, if the flats have been seeded and watered on a Monday, then they’ll be uncovered come Thursday or Friday. Any longer than that, and the crops would begin growing through the holes of the trays above them.
Fix #2: Using Durable Covers
In the video, Curtis took out a sheet of plastic that has been cut out to fit the size and shape of the Paperpot tray and placed it over the crop. Curtis used coroplast, but any material that is durable and can withstand watering will work well for this purpose.
Curtis also pointed out why we should consider putting a cover sheet at least on the microgreens tray at the top of the stack, the one under the weighted tray. In the video, Curtis uses a Paperpot tray weighted with a single large brick in the middle.
He explains that the holes on the weighted tray would be very well ventilated especially in the summer when it’s drier and warmer. This uneven ventilation, temperature, and humidity would then result in uneven germination in that top tray. Placing a cover over that tray would prevent that uneven germination.
Apart from covering the top tray with a durable sheet, some growers will use a hole-less tray for the weighted tray, which essentially does the same purpose.
That said, while this method served as a good fix for the issue for a while, after growing a bit more trays of microgreens, Curtis found that it’s simply easier and much less of a hassle to get the timing of uncovering right.
In the video, Curtis seeded a few trays of broccoli and kohlrabi and placed coroplast sheets over the top tray and over the next couple of trays underneath it, leaving the tray at the bottom of the stack uncovered.
Three days after seeding, he uncovered the trays, and the ones with the coroplast covers came off fine without any issues, but the one tray at the bottom of the stack without a cover was stuck to the bottom of the tray on top of it.
Safely separating the stuck trays. To dislodge the crops from the holes, Curtis grabbed the tray on top and gave it a side-to-side shake, careful to make little twisting motions with the tray to dislodge the crops that have grown through the holes of that top flat.
Even though that flat of broccoli was successfully separated from the other tray, had the unstacking been done even just a day later, the crops would have grown further into the holes and would have been beyond saving.
“In an ideal world, you want to get your timing right.”Curtis Stone
When all is said and done, it’s a lot easier to prevent any crops from growing through trays than it is to troubleshoot crops that have already grown through trays. In the end, the best fix for this issue is to get your timing down and uncover your microgreen trays at the right time so you’ll never have to deal with troubleshooting again.