Black spots on leaves

Discussion in 'First Time Marijuana Growers' started by FluidMotion, May 3, 2011.

  1. Hey everyone, I'm new here. Had a problem with growing that I posted to reddit's cultivation forum and they went me here. My new plant (just under 2 weeks old), has been getting lots of black spots on its first set of leaves (the 2nd set is fine). Not sure what's causing it, here's a picture:

    Additional info:
    Lighting: two 100 watt cfls, 6500k.. one 100 watt cfl, 2700k

    Watering: About every 3 days, I soak em on watering day then let em almost completely dry out.

    Ferts: None yet, these plants aren't even 2 weeks old yet.

    Soil type: garden soil from my family's garden. Its a mixture of that tan clay soil, typical dirt and sand. I figured the differences in graininess would hold water well.

    No other plants have black spots, some very slight yellowing on some of the others.. but nothing out of the ordinary for young plants.

    Please help me save her!!:(
  2. Do you spray leaves?
  3. Nope.
  4. bump.. Any ideas? I really don't want her to die.
  5. Looks like it's phosphorus deficiency....P deficent can be caused by not enough phosphorus in the nutes, ph is above 7 and can escalate with a wet soggy soil condition.

    I would check the ph of your runoff water and adjust your solution and maintain a 6.2-6.5 ph to treat a deficiency.

    More than likely your ph is off and not uptaking the p in the soil. If ph is ok, a mild dose of fertilizer with p may help.

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