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The pea plant (Pisum sativum) was grown in an ebb & flow hydroponics system until it failed; now it's in a deep water culture unit.

I noticed that the leaves were turning brown/grey. I thought this may be a disease so I sprayed Daconcil when needed, but it didn't seem to help. Thinking it might be fertilizer burn, I flushed the system, but now I noticed the leaves are drying up. To rule out the possibility of burning from too much light, I moved the light 2 inches back sideways. However, it's still progressing.

Why is this happening? Here are some details on the setup and environment.

  • Pea Little marvel (Pisum sativum)
  • pH as of now: 6.5 - 6.2 pH
  • Indoors.
  • Light is 100w 6500K (daylight) fluorescent.
  • Light period controlled by timer.
  • Light period was changed from 14 hrs to 16 hrs after light was moved.
  • next to air vent. (always cold)
  • Fertilizer is miracle-gro 20-10-10.
  • water has hydrogen peroxide in it to keep it oxygenated.
  • hydrogen peroxide ratio: 1/4 cup of peroxide per quart of water.
  • Air pump keeps water bubbling/moving to keep it oxygenated (no air stone, just a diy nozzle).

Click on the photo for a larger image
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Here's few more of the same setup: 1, 2 and 3.

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up vote 3 down vote accepted
  • next to air vent. (always cold)

  • Fertilizer is miracle-gro 20-10-10

Thinking out loud, I wonder if the constant cold air movement could be the problem (or part of the problem)...

That to me seems too strong a fertilizer, unless it's the recommend strength for growing a pea plant in an ebb & flow hydroponics system, is it?

No, but that's all I have. I have stopped using it for a week but saw no improvement

It would take (much) longer than a week before seeing any improvement, if in fact the plant could fully recover from over fertilizing (IMHO).

What is the recommend "general" fertilizer for an ebb & flow hydroponics system?

From my limited knowledge on the subject, it should be well balanced and contain essential micro-nutrients (seeing as there is no soil present).

What about the constant cold air movement, could that have contributed (to the problem)?

The air shouldn't cause a problem because the plant thrives in cool weather, but I think the problem may be the fertilizer.

"Cool weather" & "constant cold air movement" (basically a draft) are two very different things (IMHO).

Regardless of that particular argument, my gut feeling is the imbalanced (and strong) fertilizer is the cause of the problem (for what that's worth).

I recommend looking into specific ebb & flow hydroponics system fertilizers:

  • They're designed specifically for use in such systems.

  • They will contain everything a plant needs to survive, thrive in such a system.

  • They will probably cost more than "regular" fertilizer, but the additional cost should pay for itself in the returns you get from having health plants.

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