Treating rockwool cubes

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rockwool with seeds -

Rockwool cubes are a great option for germinating seeds. In order to use them, they first have to be treated. They come at a pH of around 8 and it is recommended to get that pH down before germinating. Here are the steps:

  1. Fill a bucket of water about halfway depending on how much rockwool is to be treated.
  2. While wearing gloves, add a pH downer (such as phosphoric acid) to the water, drop by drop while measuring the pH with a digital pH meter. 
  3. Bring the pH down to around 5.
  4. Add the rockwool into the bucket and soak them for a few hours or overnight.
  5. While wearing gloves, take the rockwool out when they are ready and carefully shake out some of the water. You do not want the rockwool to be soaking wet, but neither should they be dry.
  6. Place the rockwool back in the tray.
  7. Add the seeds into the rockwool using a wetted tip of a toothpick.
  8. Cover the tray using a clear plastic to let the light in but to keep rockwool from losing moisture.
  9. Place the tray in a shady area. In the aquaponics greenhouse, this can be on a shady side of the grow beds that contain clay pebbles, so the roots can find their way and the germinated seeds can be transplanted without damaging the roots.
  10. Periodically water the rockwool using rain water. First check the pH to make sure it is around 6. If tap water is used, use a pH downer to bring it to around 6.