OpenAg Wiki Archive

Archived Contents from the original OpenAg Wiki (snapshot on Apr 8, 2020)

The archived wiki only includes information up the v3.0 version of the PFC-EDU, and is here for preservation purposes. You can find resources about the latest version of the PFC v4.0 on the Personal Food Computer resources page.

Generic germination procedure

  • Photoperiod: 16hr
  • Ideal PAR: 250-350 µmol/m2.
    • Seeds and seedlings aren’t photosynthesizing yet. Light at this stage is serving as a signal to break dormancy and point the plant to what’s “up.” So long as there is “some” light to provide that signal, germination should be successful.
  • Distance between the light and the top of the foam cubes: 14” (where the PAR was measured)
  • Nutrients: 150 ppm nitrogen from our standard A/B protocol.
  • Watering: wet cubes twice a day. The foam cubes naturally dry between cycles.
    • We use a flood and drain system, which keeps the cubes/seeds moist all day. See picture below. The idea is that twice a day, the cubes get flooded in water, keeping them moist until the next flood.
  • Ideal temperature:
    • Rack / tub is open to the ambient climate.
  • Ideal humidity:
    • Rack / tub is open to the ambient climate.

Flood & drain rack

mini seedling germinator

At our large Bates facility, we need hundreds of seedlings at a time to start a new experiment in the Food Servers. In our tiny lab on the MIT campus / Media Lab building / OpenAg offices, we only need 12 seedlings per PFC. So Rob Baynes built this scaled down seedling germinator for his own use and provides these “plans” for you as-is.

design

The simple design is the small pump runs for one minute every 12 hours and puts enough water+nutrients into the clear bin to wet the foam cubes to the seed level. The fluid drains out via gravity back into a hole cut into the bucket lid. There is a small stick that holds the fill corner up a bit, so flow is down to the drain.

Adjust the pump flow rate and partially occlude the drain hole so the fluid drains at a slightly slower rate than the pump.

The second timer turns the grow light on for 16 hours.

Any grow light will work, spectrum and power don’t really matter. Just the ‘light’ itself and some of the warmth are what triggers the the seed to become active.

In the picture you may notice that we taped a bit of black plastic inside the bin. That is to make sure the foam cubes are not sitting in left over fluid that doesn’t drain out.

parts

mini-seedling-germinator.jpg