Hydroponics workshop: Root aeration

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Aeration for the roots

Roots all in water with no air => drowned plant
Roots in air without high humidity => those roots turn brown, die

Three ways to plan a system with aeration

  1. Roots take in aerated water (ex: Deep Water Culture).
  2. Roots alternately exposed to air and water (ex. Ebb and Flow).
  3. ‘Division of labour’: some roots in still water, others in very humid air. The humidity is the key, along with air roots. Important for ‘off-the-grid’ systems (ex. Kratky).

Plants optimize their root structure for their circumstances. Major changes to a system can cause setbacks while the plants adapt.

What are air roots?

‘Fuzzy’ or ‘hairy’ roots that grow in humid air pockets. They help take in air but they are delicate! If they get wet they lose their ‘hairs’ so only seen in non-circulating systems.

Roots should be perfectly white, fluffy, and abundant. If not:

  • Too much dry air: seal air leaks and avoid opening it up.
  • Is pH consistently kept in an appropriate range?
  • Is the container lightproofed?
  • If you improvised the net cup, does it have enough holes?
  • Roots that are completely brown, very thin, and silky are dead.

The existing roots generally won’t improve, but fixing the problem will stimulate growth of healthy new white roots.

Fixing air leaks – some likely suspects:

  • Cover unused net cup holes.
  • Media in net cups should go up at least as high as the holes.
  • Soft media should be packed densely and more may need to be added later if may need more added later.
  • Large hydroton can be covered with plastic wrap, just make sure if doesn’t restrain the plant.
  • If there’s a container with a lid, how well does the lid seal?

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