Compliments & Gratitude....& Microgreens?

by Paul Kim
(Atlanta, GA)

I am working on building an indoor micro-green system using sure-to-grow mat. I've considered NFT, but there are two drawbacks: 1) the edges roll up and dry out, and 2) I want to go organic and am concerned about the drippers clogging. I am trying ebb and flow, but concerned that too much water will stagnate and cause disease.

1) Can you recommend a synthetic grow medium (other than sure-to-grow)?

2) What is your opinion on sure-to-grow mat for micro-greens?

Answer: An ebb and flow system would be a good solution for you. Stagnant water would not be a concern, as the water in the system will not be standing long enough between flood cycles to actually stagnate. Another solution would be to use a small water pump to maintain a constant (although very shallow) flow of nutrient solution over the capillary mat at all times. This would at least prevent the edges of the mat from drying out.

Using organic nutrients in a drip system can be tricky. If you are set on this path, you will need to use an in-line filter with your water pump to prevent any sediment in the nutrients from clogging your drip emitters. This is a non-issue if you choose to go with a flood and drain system or a deep water culture (DWC) system.

By keeping several inches of nutrient solution flowing through the bottom of My Most Successful Homemade Hydroponic System, I was able to run an NFT type hydroponic system very successfully without the need of any capillary mat in the bottom. Whenever you can eliminate recurring expenses (like having to purchase rockwool or capillary matting), you increase the profitability of your operation.

If you are only growing micro-greens, you may want to consider the hydroponic system that I linked to above....or perhaps a DWC system for lettuce. These systems are very popular with commercial salad producers. Lettuce, spinach, and herb crops all do very well in these systems. Growing in standing water does not seem to bother these types of crops as long as you keep the nutrient solution well oxygenated with an air bubbler. It also becomes important to keep the nutrient solution between 65 and 72 degrees, as warmer water will not hold as much dissolved oxygen and may begin to cause problems.

In my opinion, using capillary mats to grow micro-greens would actually be making things more difficult than they need to be....especially since they grow very well in systems that require much less maintenance to manage (not to mention the need to purchase new capillary mat from time to time). The ideal situation would be a low-maintenance system that does not require the purchase of new capillary mat or new rockwook growing medium to run properly....the profit margins on micro-greens can be slim (especially if the operation is a small one), and as I mentioned before, all recurring expenses come right out of your bottom line.

I did come across an interesting site while looking into other sources for matting. It is ebbandflowmat.com. If you decide to go with capillary matting, this is worth checking out. The Alternative Garden Supply catalog also has some capillary matting products. If this were my operation, however, I think I would use some type of DWC system with expanded clay pellets as the (re-usable) growing medium. I hope this helps you out, and Happy Growing!