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Thread: Plants turning yellow 5 weeks into flower?

  1. #1
    420 Member icky's Avatar
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    Exclamation Plants turning yellow 5 weeks into flower?

    I know its normal for some yellowing well into flower but it's getting out of hand now. The Flowers were growing well but now they seem to have slowed to a crawl. They are not as thirsty as they were either. Even some of the new growth has signs of a little yellowing. I'm so close, now I'm worried.


    What Strain is it? Unknown from bag
    Is it Indica, Sativa or Hybrid? What percentages? looks sativa
    How Many Plants? 5
    Is it in Vegetative or Flowering Stage? flower
    If in Vegetative Stage... How Long? vegged for 2 months
    If in Flowering Stage... How Long? 5 weeks
    Indoor or Outdoor? indoor
    Soil or Hydro? soil
    If Soil... What is in your Mix? MG 6 month/perlite.
    If Soil... What Size Pot? 3.5 gal
    Size (Wattage) of Light? How Many? 1 400w HPS
    Is it Air Cooled? no
    Temperature of Room/Cabinet? 60-80 (temps getting low overnight) heater cant keep up.
    RH of Room/Cabinet? 50-60%
    PH of Medium? 6.8 according to my shitty stick in the dirt probe.
    Any Pests? have seen a few nats. not an epidemic.
    How Often are you Watering? every 2 days, full watering.
    Type and Strength of Fertilizers used? first time ever fertilized used 1/4 strength jacks classic bloom booster 10-30-20, week 1 of flower. and second dose 1/2 strength in week 3.
    Size or Square Footage of Room? 12x15



    I have to wonder 2 things! temps getting too low at night and I also used water from my tap with a water softener/ salt tank system, Is the plant salted up and locked out? How to fix this?

  2. #2
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    Re: Plants turning yellow 5 weeks into flower?

    I just had this problem but in veg. My probelm was not enough nutes. Maybe a nitro def in this case? I use tap water too , so i let it sit out for 24 hours in a bucket. Then i airate the water for a couple hours, before adding nutes. Not sure as to the temp being the cause, but i wouldnt be happy with my ladies getting down to 60f for any amount of time.

  3. #3
    420 Member icky's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    It seems the more I read the more I think the low temps are locking out the nitrogen and since a mid to late flower nitrogen deficiency is normal, the problem is compounded.
    I turned the heater up, I don't know if I should feed it nitrogen or not. It likely has nitogen there just can't absorb it. I just want the dang buds to start growing again!

  4. #4
    420 Member Stoned4daze61's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    Use a Nutrient that is high in Nitrogen. A Bloom booster is high in phosphorous and potassium but low in nitrogen. Are you pots drying out normally ? If they stay moist longer then usual you may have a nute lockout. You don't need to supply as much nitrogen during flower as veg, but you still need a decent steady amount. Especially if those are sativa's, since the flowering time is longer it will need a steady amount of nutes to reach full potential. You want to give nutes every other or every 3rd watering.

  5. #5
    420 Member icky's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    They are not as thirsty as before. growth has stopped. I think it was the room temp. The MG soil seemed to work really well for 2 months of veg. and into 1 month flower, plants grew like crazy. but the temps have been dropping and I realized when the 400W hps goes out the heater wasn't keeping up. I never go in there after lights out so "I think" the cold has been locking out N. Someone please correct me if I'm wrong. I turned the heater way up and I hope in a week or so they start growing again. I added a 1/4 dose of 20-20-20. to one plant and totally flushed her twin sister. 6 gal. just to see if one does better than the other. Hope I'm on to something here.

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    420 Member Fuzzy Duck's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    Well rule of the thumb is house temperatures rarely drop blow 17c / 62f even in the colder months but can happen in the older style of house/drafts etc as far as i'm aware i never seen my own house temperature drop blow 16c / 60f - this is all based upon the fact the heating is turned off & temperatures stated are an average ambient.

    Temperatures dropping below 15c / 59f can induce plant shock.

    Remember heat/warm air rise's meaning upstairs will have a higher ambient temperature by a degree or 2, than a grow room down stairs.

    Some other stuff worth a read...

    Nitrogen - Plants need lots of N during vegging, but it's easy to overdo it. Added too much? Flush the soil with plain water. Soluble nitrogen (especially nitrate) is the form that's the most quickly available to the roots, while insoluble N (like urea) first needs to be broken down by microbes in the soil before the roots can absorb it. Avoid excessive ammonium nitrogen, which can interfere with other nutrients. Too much N delays flowering. Plants should be allowed to become N-deficient late in flowering for best flavor.

    Magnesium - Mg-deficiency is pretty common since marijuana uses lots of it and many fertilizers don't have enough of it. Mg-deficiency is easily fixed with teaspoon/gallon of Epsom salts (first powdered and dissolved in some hot water) or foliar feed at teaspoon/quart. When mixing up soil, use 2 teaspoon dolomite lime per gallon of soil for Mg. Mg can get locked-up by too much Ca, Cl or ammonium nitrogen. Don't overdo Mg or you'll lock up other nutrients.

    Potassium - Too much sodium (Na) displaces K, causing a K deficiency. Sources of high salinity are: baking soda (sodium bicarbonate "pH-up"), too much manure, and the use of water-softening filters (which should not be used). If the problem is Na, flush the soil. K can get locked up from too much Ca or ammonium nitrogen, and possibly cold weather.

    Phosphorous - Some deficiency during flowering is normal, but too much shouldn't be tolerated. Red petioles and stems are a normal, genetic characteristic for many varieties, plus it can also be a co-symptom of N, K, and Mg-deficiencies, so red stems are not a foolproof sign of P-deficiency. Too much P can lead to iron deficiency.

    Iron - Fe is unavailable to plants when the pH of the water or soil is too high. If deficient, lower the pH to about 6.5 (for rockwool, about 5.7), and check that you're not adding too much P, which can lock up Fe. Use iron that's chelated for maximum availability. Read your fertilizer's ingredients - chelated iron might read something like "iron EDTA". To much Fe without adding enough P can cause a P-deficiency.
    We are a culture fully immersed in the ideology that truth is what we see and what we hear. Yet we hire lawyers to manipulate truth, we hire PR and marketing firms to create truth, and we hire investigators and private detectives to uncover truth. The problem to which I am affected every day is truth in the cannabis industry.

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    420 Member SSNUGS's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    It is definitely a lockout issue. Also the salt in the water from the softener is a problem. You may want to get a water filter there are a couple out there that work well. I personally use one called a tall boy it takes the chlorine and other hard minerals out of your water using a duel filter. Air temp isn't the issue this is all about your water and nute lockout.


  8. #8
    420 Member icky's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    The room is in the attic, thats why it gets cold. I am on a well so no chlorine. I also have a top of the line water filter system w/blacklight. I just don't know how the softener works and if it actually adds too much Na to the water. I flushed one plant a few days ago but it still has damp soil and no new growth. SO, "sigh". still not sure if its salt locked or temp shocked. Def. has a N def. but which issue is causing it and how long will it take to see improvement in the new growth even if I fix it? I got the temps up to 65 F overnight which was pretty good for what it was outside. 75-80 all day with the hps lamp on it. I was thinking I should foliar feed them as an attempt to give them what the roots won't until I figure it out. I shouldn't have a mold problem, humidity is too low for it. So if its salt I need to flush right? how much tho? 3 1/2 gal pot. The one flush I did was 6 gal.

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    420 Member icky's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    @Fuzzy! Thats a great read man, thank you!

  10. #10
    New Member putembk's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    That looks like a classic case of nitrogen lock out. What is the ph of your runoff? You might want to check that as it may have dropped so low that the plant can't absorb the nitrogen you are giving it.
    Plants still need some n in flower, check the label of your nutes.

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    420 Member FrankFoster's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    If cold can cause N lockout, thats news to me.

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    420 Member OG13's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    I can't believe the softener would be hooked up to the kitchen tap, where I assume your filter is. Softeners are for making soap lather up, not for drinking. The ONLY filter that will remove the salt is a Reverse Osmosis.
    Fast, Cheap or Good.....pick two

  13. #13
    420 Member icky's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    Quote Originally Posted by OG13 View Post
    I can't believe the softener would be hooked up to the kitchen tap, where I assume your filter is. Softeners are for making soap lather up, not for drinking. The ONLY filter that will remove the salt is a Reverse Osmosis.
    The softener/filter system and uv lamp are all in the basement right after the water tank. the tap has a britta on it. The water is excellent drinking water. All I'm saying is I don't know if the water is good for plants. Na speaking. I dump 80 lb bags of salt pellets into the hopper once in a while. the water does not taste like salt so its being removed at least to a point. why am I explaining this? I don't ever remember saying it was hooked to anything or that I installed it to help the drinking quality. I appreciate the posts that are actually trying to help out. As soon as they dry up a little, I will flush the shit out of them. room temp is good now.

  14. #14
    420 Member FrankFoster's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    The ph of your water will have an effect for sure. But late in the game, that yellowing could your friend. The flush will reset and help

  15. #15
    420 Member Fuzzy Duck's Avatar
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    Re: Plants turning yellow 5 weeks into flower?

    Quote Originally Posted by icky View Post
    @Fuzzy! Thats a great read man, thank you!

    Hope it helps
    We are a culture fully immersed in the ideology that truth is what we see and what we hear. Yet we hire lawyers to manipulate truth, we hire PR and marketing firms to create truth, and we hire investigators and private detectives to uncover truth. The problem to which I am affected every day is truth in the cannabis industry.

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