MicrogreenBox, an open source project

I am new here and wanted to introduce my project, which will provide enough microgreen sunflower and broccoli for a green smoothie every day.

I have been logging my steps toward an automated MicrogreenBox on my youtube channel.

Here is a recent video with an overview: https://www.youtube.com/watch?v=pSPgjQMyBD4


Greetings @skyl4rk, welcome to the forums! Cool microgreens project! Thanks for sharing the video! I’d enjoy learning more about setup design as I’m working a similar project. In my case, I designed and fabricated a tray/catchment system to optimize drainage. I’m approaching the environmental controls on a larger scale (by rack) but our basic approach appears similar.

Again welcome, looking forward to hearing more!

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At the moment I am testing a number of substrates for hydroponic grows in trays: pvc screen, tule mesh, paper towels and none. At the moment I think that paper towels for brocolli and no substrate for sunflower may be the way to go. If I have to, I will go back to coir.

I have a lot of other variables to work through to find out what the seedlings like and what produces the best yields.

I have tried no nutrients (straight water) and mild nutrient solution and the results are better with nutrients. For 10 day sunflowers, I get about 2x the seed weight yield with only water, and 4x to 5x seed weight yield with 25% of full strength nutrient solution (2g NPK, 2g Calcium Nitrate, 1g Magnesium Sulfate in 4 gallons). So a clear winner there.

One issue is that on day 3 there is a strong odor - urine or aquarium smell. It is quite strong. It seems to go away by day 5. I suspect it is coming from decaying seed hulls but ???. My temperatures may be too high. I am using trays which hold puddles of water/nutrient solution. I am using them because they were cheap and easy to find. I would prefer to use a flood and drain tray with a sump that fully drains the tray. But I will see if I can make what I have work.

I am in the middle of trials and they don’t always work out well, it is a matter of testing the edges to find the ideal method. So I am not filming my current trials. But when I get my system dialed in, I will start posting videos with recommendations on how to successfully grow microgreens in the system.

Using a flood and drain system, paper towel as substrate in perforated trays for broccoli seed works well. No substrate is needed for sunflower seed, I am just scattering dry seed in the tray.

The seed trays need to be clamped down in the flood tray so they don’t float during the flood cycle.

I have set up three phases: Germination Phase, Grow Phase and Harvest Phase. The Germination Phase has a flood schedule every 6 hours. The Grow Phase has a flood schedule every 8 hours. Both these phases have the same heat set point, with one exception: I set up a Hot Day, on Day 6, the heat set point is boosted a bit to encourage the sunflowers to drop their hulls.

Actual settings for heat: I try to put the heat set point at 72F and the heat set point plus hysteresis at 76F. This means the heater turns on at 72F and off at 76F, while the fan turns on at 76F and off at 72F. Either the heater or the fan is running at all times. The Hot Day boost should bring the settings up by about 3F, or 75F to 79F heat range.

The Harvest Phase runs the fan continuously with no heat. This is to chill the plants a bit and stop their development to give me a longer window to harvest while they are still crisp with no true leaves. The flood cycle runs every 36 hours, the intent is to dry the microgreens a bit but still give them enough water to live.

This is a video log of a trial grow:

The harvest was about 600 grams total. I can improve this by reducing the amount of time that the fan runs. The fans were chilling the sunflowers.

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Automated Microgreens Crop Order of Events