Yellow leaves - is it the low soil ph?

Discussion in 'Sick Plants and Problems' started by Laica_, May 5, 2016.

  1. #1 Laica_, May 5, 2016
    Last edited: May 5, 2016
    Dear wisemen,

    First crop and I'm off to a wrong start.. Both of my ladies showing disturbing signs of stress (yellow leaves right from day 1!)

    Some details first:

    * ladies 7 days old
    * 600w HPS Air-Cooled (plants at 12 inches from lights)
    * Temperature around 24C (min 19C - max 25C)
    * Humidity around 40% (min 10% - max 60%)
    * Soil: Plant Magic Plus mixed with 20% Perlite
    * Dry/wet cycle with watering every 24hs/36hs.
    * Watering with light tap water at 6.9ph ( left standing for min 24 hs. to evaporate impurities).
    * Last three runs off (watering with 6.9ph) were;
    48 hs. ago: 5.0 ph
    24 hs. ago: 6.0 ph (added 'crushed' Garden Lime)
    Today: 6.5 ph

    For testing purposes :
    * Run off from (clean) straight from the bag soil : 5.0ph

    How would you advise me yo proceed to properly look after my girls ??



    Watering can

    Image1462407793.048971.jpg Image1462407811.707801.jpg
    Run off
    Image1462407829.099168.jpg Image1462407839.839752.jpg Image1462407855.130627.jpg Image1462407867.552348.jpg Image1462407888.903216.jpg
  2. 6.9ph in and 6.5ph out. But please bear in mind that this is due to the lime I added yesterday ... Before that I was watering with the same can and getting 5.0 ph out..
  3. Well it looks like you have solved your problem! Plant Magic plus looks pretty is basically all peat so that explains the low ph. Garden lime was the thing to add and you got the ph up to where it needs to be. If you can keep it anywhere in the 6's you'll be fine. I usually try to keep mine between 6.3 - 6.7 in soil

    Light: check
    Temp: check
    Soil: check
    Wet/dry cycling: check
    Ph adjustment: check


    you're good to go :love-mj2:
    • Like Like x 1
  4. Like lazy said. Your problem should be solved. Just wait about a week so your baby could start showing progress. One of my plants if starting to yellow up at the bottom and I watered them all with a bit of epsom salt. It's all in the waiting now.

    Sent from my SM-G935P using Grasscity Forum mobile app
    • Like Like x 1
  5. P.s. next time I recommend using 3/4 fox farms soil and 1/4 coco coir. That's what I'm using

    Sent from my SM-G935P using Grasscity Forum mobile app
  6. Btw what strain(s) are they Laica?
    • Like Like x 1
  7. Hi LazyBlazer, they are one Cropical Fruit auto and one KO Crop auto.. But how long till I see 'results'? i.e. green healthy leaves ?

    Sent from my iPhone using Tapatalk
  8. Dear wiseman, I'm afraid we need to start over and consider all the options from the beginning. My ladies continue to show signs of distress with yellow almost white'ish leaves, and I am clueless about what is wrong..

    Soil: same as before, 80% plant magic and 20% perlite. Plus lime.
    Pots: increased to 1 gallon (4.5litres) - Bigger 4 gallon ones on its way (18 litres).
    Water: no nutes with 7ph in and 6.5ph run off.
    Watering: every 3 days approx.
    Grow tent Temperature: min 19.9, max 25.5
    Humidity: min 35%, max 80% (when the heating tube kicks in, the extractor fan stops and humidity goes up).
    Humidifier: bucket with towel and water
    Ventilation: one small fan inside the tent and 6 inch extractor (which works as long as the temperature doesn't drop below 21° C) with negative pressure. There is no intake fan but a vent is constantly open
    Lights: 600w air cooled
    Light schedule: 18hs/6hs
    Distance from lights: increased to 45cm (5.5 feet).
    Grow room: 1.5mtrs x 1.5mtrs

    Age: 10 days old

    Are there any other parameters that I should be looking for clues on what might be wrong?

    Please find attached pictures of both my ladies and the tent.

    I really appreciate your help as I am both disappointed and frustrated with myself for being unable to understand what these girls are telling me.

    Much love


    Image1462836826.866385.jpg Image1462836840.024308.jpg Image1462836848.418250.jpg Image1462836856.726240.jpg Image1462836865.361989.jpg Image1462836873.932876.jpg

    Attached Files:

  9. next time try using a 1 to 4 ratio. 3 parts fox farms ocean grow and one part coco coir.
    my babys are nice and fat and thats all ive been using

    Sent from my SM-G935P using Grasscity Forum mobile app
  10. If ph isn't a problem now I can think of 3 possible things that could be the culprit. 1) Over watering, even though they don't really look overwatered. 2) Too much light. You said your plants are very light yellow almost turning white...could be light bleaching. I would move the seedlings under some fluorescent lights if you have any. If not try raising your light another foot. 3) There could be something in that "Plant Magic" soil that they just aren't agreeing with. Also I would have waited a little bit to transplant. They will need a couple days to reestablish before they can focus on fixing the problem at hand.
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  11. 600W for a seedling is your problem. Waaaaay to many Lumens for her! : )
    • Like Like x 2
  12. Another potential issue with this could be chlorophyll levels. Chlorophyll is the pigment in plants that makes them green, but it is also very very important, because it is critical in photosynthesis.

    Chlorosis is basically a disease in a plant where chlorophyll levels are diminished, and one telltale sign is yellowing. It can be caused by high alkalinity (pH is too high; needs to be more acidic), poor drainage (sitting in water all the time) or not enough nutrients. And this is bad; it makes photosynthesis less efficient!

    Between 5.5 and 6.5 is usually ideal for most plants. You are JUST over that number. So try to bring that pH down closer to the lower part of that range, and you should (hopefully) see a greener, happier plant. Which makes for a happier you! Haha
    • Like Like x 1
  13. #17 Laica_, May 11, 2016
    Last edited: May 12, 2016
    Thanks for the tips.

    1) I'm fairly confident that watering is under control and soil drainage is good (perhaps even too good).

    2) SOIL: I don't know how to find out whether there is something wrong with 'Plant Magic'. Beyond keeping an eye on PH (which I have already adjusted) I don't know what other parameters to look at. Just a gentle reminder that water run off used to come at 5.0 ph until I adjusted the soil with lime. I will target a 6.3 ph as per CityOfStars comment's and look for an improvement in leaves Color.

    Ilove562 I don't have access to FoxFarm where I live. Any other brand you would recommend ? Canna Soil? Bio Bizz ? Is there a good chart / thread on this? It would be great to find a soil mix which is spot on in terms of PH range.

    3) I think all of you might be onto something with light potency / potential light burn.
    Leaves are very yellow almost white for the top ones and their tips are curled up with some leaves bending as well. I have raised the lights another 6 inches. It's worth mentioning that lights had been just a foot distance from seeds until 4 days ago (I was following the chart attached below). Given that it's an air cooled hood I felt quite relaxed about its proximity to the plants. I could had been epically wrong on this. I don't have fluorescent lights but I do have an adjustable ballast. Should I reduce the input to 400w or 250w for the 600w bulb? Or just keep raising the hood (including the latest adjustment.. currently at 23 inches)?

    Thank you in advance for reading and sharing your experience and knowledge.

    Much love



    Black spots

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  14. Yes now that you have leaf bending/curling I'd say its definitely light burn/bleaching.

    "Given that it's an air cooled hood I felt quite relaxed about its proximity to the plants. I could had been epically wrong on this." - I think you're relating light burn to heat stress. The air cooled hood will definitely keep the light cool enough for the seedlings. Excess heat isn't the issue it's the excess light. Yes I would dim the bulb

    Good luck!
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  15. Thank you for the feedback. I can confirm that it was light burn. I swap the 600w bulb for a 400w and the girls thrived.[​IMG]
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