Watering Frequency of NFT Microgreens
When using an Auto Watering System for Microgreens we have to keep in mind a couple of Factors. 1. Watering Frequency
2. Dissolved Oxygen in Water
3. Nutrient Strength
4. Flow Speed
5. PH of Water
NFT Systems are designed to run 24 hours a day 7 days a week, but with Microgreens some exceptions must be made. Through our own testing we have found that the frequency and volume of water given to Microgreens can impact the quality of your final product. What makes this more challenging is that not all microgreens enjoy the same amount of water. Some Varieties like Arugula or Red Cabbage inherently prefer less water than broccoli, sunflower or others. So in the interest of keeping everything under the same timers and watering cycle we set out to find the solution.
Keeping it simple:
Each Cycle is 30 Minutes of Steady Water (Not Enough to Move Seeds approximately 6 GPH) - Based on an 18/6 Light Cycle we water our microgreens 1 hour after lights on
- Second Cycle is 5 hours after that.
- Third Cycle is 5 Hours after that.
- Fourth Cycle is 1 hour Before Lights out.
Using the above mentioned watering Frequency across an 18/6 light cycle has given us the most reliable results and even growth throughout the channels. (See Below)
Dissolved Oxygen in Water NFT systems which are running 24/7 do not require additional Oxygen to be added to the reservoir, but as you can see above we aren't running things 24/7 so the best practice in this case is to add an aerating stone. Typically we would suggest running an aquarium air pump with a minimum of 2 air stones. In the Reservoir you want to keep things circulating so place the stones at opposite corners from one another. Without enhancing the oxygen levels in the water you will see that towards the end of your channels there will be less abundant growth. Nutrient Strength When Growing Microgreens in an NFT System you don't require nutrients however in the final few days before harvesting there is a noticeable impact on the leaf size and stem strength of those who receive and those who don't. Rather than complicating things we run a small amount of Nutrients through our system for the entire grow. Keeping in mind some of the following things. 1. When measuring dosages we only use 1/2 of the suggested dosage on the bottle for seedlings. 2. Use highly Chelated Nutrient Solutions 3. Do not use things like kelp or seaweed as this will give an off odor to your greens after packaging. It is also harder to maintain a clean system with these types of nutrients. 4. If you use a three part nutrient always add the MICRO first and allow it to disperse for a few minutes before then adding your Grow and Bloom. Water Flow Speed At the Beginning we had our NFT Microgreen System running at a very low drip, with more frequent cycles. What we found doing this was that the microgreens were not seeing a proper exchange within the substrate we use (Biostrate Felt). We assume that this would be similar with any other substrate as well. We were seeing some leaf yellowing, roots were periodically getting brown sections and the microgreens closest to the water input were thriving, with those further down the line looking stunted. As we Increased the water flow over time we noticed more uniform growth down the entire channel. The rate we use is regulated by Emitters at approximately 6 Gallons per Hour. PH of Water Originally we planned on running an Automated PH system for our Microgreens however it just wasn't in the budget so we got ourselves a couple of PH/EC Pens and hit the ground running. Our water has a natural PH of around 6.8 which is somewhat suitable to grow in however we found the best results trying to keep our PH range between 6.2 and 6.5. Using this PH range we are not experiencing any problems with growth. However when looking at which PH down or UP Solutions to use we highly Recommend CYCO Nutrients PH Down or PH Up. This solution is much more stable than others and wont leave you with wild fluctuations on a daily basis. Conclusion Microgreens can successfully be grown using an NFT system. Once they are matching the parameters above you will find growing them to be very low maintenance. Thanks for reading! Leaf Sweets Urban Farm.