Updated: Nov 3, 2022
Over the past several years, the Nick Greens Grow Team has put thousands of hours into growing microgreens for commercial sale. During that time we’ve learned several hard-earned lessons that growers can use to avoid these common issues and problems. Here are our top six most common challenges/problems with growing microgreens.
Uneven germination – Uneven germination is caused by either human error or lack of moisture. We can’t solve the human part, but here are a few tricks we learned along the way: Build or buy a tent to house your black 10X20 trays for the first few days of growth. Make sure to spray trays at least once a day and reclose the tent. Depending on the variety, remove trays after two to three days You are seeking 90% humidity and might need to experiment with the location of your tent several times. Alternatively, you can use a humidity dome with a black 10X20 over the dome for your higher end varieties such as Shiso or Borage.
Mold and mildew – Mold and mildew starts during the germination process (because of the high humidity) but does not reveal itself until four or five days into the grow cycle. Reducing this problem starts with air-flow, Add small mini fans or an inline blower with carbon filter and intake booster fan for fresh air. Spray your plants with Terereplenish during the germination process which naturally decreases mold due to the presence of beneficial, free living microbes.
Harvesting difficulties - Even if you buy an expensive harvesting machine it might not be worth it. The only successful way to harvest microgreens in our experience is by hand. Use a decent pair of shears (we use the Fiskars titanium shears with the black and gray handles) and make sure you have a high stainless steel table to cut on. Ideally one that rolls and has a shelf underneath. (Anything smaller will cause ergonomic issues for you or your growers.) Line your food grade containers with paper towels (to absorb moisture) and refrigerate within 30 minutes of harvesting.
Too many varieties to choose from – It not easy choosing which varieties of microgreens to grow. We have had great success growing the following: Pea Shoots, Red Rambo Radish, Hong Vit Radish, Kale, and Broccoli. Each is easy to germinate, and turns in less than 10 days. Also by mixing everything listed above, you can create a great tasting rainbow mix. Trying to grow anything more than six or seven varieties at time will be a nightmare for your crop planning and lead to disappointed customers.
Costly fiber-based media mats – Fiber-based media mats, like hemp, can be very costly growing media, and can significantly reduce or wipe out your profits. Any media that costs more than 10% of your revenue per tray is too expensive and your goal should be to achieve a 5% ratio. We found the most efficient and profitable mats are burlap. You can buy good quality, safe burlap, or you can partner with a local roaster and reuse coffee bags which are more sustainable and generally free. In either case, you need to cut mats in advance, and then soak with 3 ppm of H202 for half an hour before seeding. Burlap doesn’t produce as much yield as soil, but it grows faster and is less expensive. If you are contemplating large production, you will want to grow on burlap or some other fibrous mat. The downside of burlap is that it dries up quickly and requires equipment with a timer and automatic feeding system. The best systems are supplied by Crop-king NFT, or you can build your own home-made racks with botanicaire flood trays.
High lighting costs - While lighting and electricity costs for indoor crops are relatively high, microgreens typically need less than 4 DLI a day -- equivalent to 8 hours a day at 125 PAR. We found using a combination of LED and fluorescent is the best.