Yellow and brown bottom leaves

Discussion in 'Sick Plants and Problems' started by SlowMo, Mar 26, 2015.

  1. I have two almost identical plants - same strain (Easy Ride autos), same pots, soil mix (2 parts Happy Frof - 1 part pearlite), same 6.5 pH'd nute and distilled water schedule, same everything. They are in their 7th week - starting the 3rd week of flowering.
     
    One plant is doing ok with minor yellowing and some brownish spots while the other started to develop patches of yellow & brownish dried out leaves among the older lower ones. The stems of the affected leaves are dark purplish color - all other stems are green.
     
    They've only had a single nute feeding of half strength (1 mL/gal) DynaGro "Bloom" (3-12-6) plus a half dose of Cal-Mag since going into flowering. I watered only today with 6.5 pH distilled so I could check the pH of the drainage water. It was 6.5. I'm religious about pHing not overfeeding and watering so I'm pretty sure it isn't connected with nutrient lock.
     
    Thanks for any help friends!
     
     
     

     

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  2. Hmmm... some of the pics and descriptions at growweedeasy.com would seem to indicate a phosphorus defeciency.
     
    So, even though I already watered them heavy this morning (but not quite a full flush) and won't again for probably about 5 days, can I still give them a 3-12-6 nute treatment today or should I wait until the next scheduled feeding?
     
  3. Yeah its common misconception that its okay to feed store bought soils 6.5phed water all the way through. Thats a bad idea.

    As soil decays over time, sulphuric acid causes ph to drop. As it falls and you maintian a 6.5 ph your ph slowly slides below six and since you dont do anything (like watering with a 7.5 ph to offset the balance) you help the plant slide further into the low ph area.

    Theyre probably just a bit hungry. Since you poured calmag into soil (bad idea, as magnesium and calcium are almost always the most abundant elements in soil) you may have exacerbated the problem by causing magnesium to bind up parts of the soil.

    If they were mine, id flush them well. Then id pick up some chicken manure for 2 dollars at home depot. That bag should last you a year if youre growing 30 plants at a time. Top dress with that unless you can get castings :) even better.

    Consider adding some oyster shell powder to help buffer the ph a bit if you can.

    They may just be hungry but it looks like ph imbalance and hunger to me.
    ~ poke
     
  4. Thanks for your wise counsel! I do appreciate it.
     
    I'm pretty sure the pH has actually been between about 6.3 and 6.7 throughout the grow. I use a calibrated meter (calibrated with 7.01 and 4.01 calibration solutions) as well as pH drops to check it against each other. 
     
    Anyway, I just flushed them pretty thoroughly with a half strength pH'd Bloom nute (3-12-6) - distilled water solution like they recommend at groweedeasy.com. I'm hoping this will help any under/over nutrient issues. 
     
    I know that towards the end of the grow the leaves may turn probably turn yellow as lower leaf nutrients are stolen for use in flower production but I still have a month of flowering left. 
     
  5. You could consider a pot up to another size pot then flush well, but as these are overfed autos, I'd just stick with the flush and improve my lighting by getting more 2700k light in there to prevent these shitty squat internodes you have.
     
    But the most important thing you can do here is understand that reading
    the potential of hydrogen in soil is a fools error from the outset
     
  6. These plants haven't been overfed nutes. I only nuted every third watering (at half strength each time) and I only water when the soil is no longer moist almost to the bottom of the 3 gal smartpots - around 5 days on the average.
     
    Also, I have two identical strain plants and they each have gotten the exact same nute-water regimen, soil mix, etc, but only the one plant is showing these symptoms - which seems a little odd to me. 
     
    I assume by the reference to "reading the potential of hydrogen" you are referring to checking pH of what I put on the plants. From what I've read at dozens of sites, in the so-called grow "bibles, advice here at the grow forums, and various youtube videos, I think I'll stick to bringing the pH between 6 and 7, even if it is a fool's error. I really can't see any harm in not applying overly acidic or caustic solutions to my plants. But whatever... what do I know - I'm a noob.
     

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