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New Plant Growth Turning Yellow since Switch to HPS. Can't find problem please help.

Discussion in 'Marijuana Plant Problems' started by vancitychopshop, Mar 23, 2011.


    vancitychopshop Member

    Hi guys.

    Currently growing in a hydroponic fill and drain bucket system.

    Was vegging under 1000w MH, plants were vigorous and healthy. growing fast and green.
    using Lucas Formula with GH nutes for feeding. have had several successful grows using this system.

    Put the plants into flowering and turned on our new HPS lights. 4x1000w. The plants are 2 feet away from the light. After a day, the new growth on the plants is coming out yellow and plant growth is slowing down. The tips of the leaves are turned down as if they are protecting themselves.

    My ppms are 940. (ive done full grows using this formula with no problems in past) and the PH is 5.6-6.0

    I have been told by other growers repeatedly that "you can't give your plants too much light"

    Temperature is not the problem, air temp right by the top leaves is a cool 24c and there is lots of airflow in the area.

    I feel like i am doing everything right and cannot figure out what the problem is.

    Are the lumens too intense? (4 x 1000w in cool-tubes 2ft from the plants)?

    Please help!

    PICS (THIS happened in ONE day. please help!)

    C02 = 1200ppm
    PH 5.7
    Nutes: 940ppms
    Temp 24c
    Airflow : check
    plants 2ft tall.
    lights: 4x1000k
    Height above plants: 2ft

    vancitychopshop Member

    PS: the only difference between this grow and the last is how much power is on. is it possible my nutes are too low and the plants don't have enough to work with with so much CO2 and Lumens?

    Stomata Well-Known Member

    Might be light bleaching. I've never seen it myself but that's a possibility I guess.

    vancitychopshop Member

    i doesn't look like bleaching. the new growth is just coming out yellow. Ill post some pics later.


    did you switch to bloom nutes with a low N?

    vancitychopshop Member


    rayb73 Member

    hello,i had the same problem awhile back,mine was do to root rot.im not saying you have it but thats how my plants were as soon as i put them under 400watt hps.try and post some pics

    Serapis Well-Known Member

    Sounds like a lighting issue to me, but pics would be great... don't forget, if plant is showing sex, the tips tend to turn lime green on indicas.
    suTraGrow likes this.

    suTraGrow Well-Known Member

    Really? never heard that ones before. Learn something new ever day ehh :-D Any information as to why this happens with indicas and not sativas. Or why just in general?

    Serapis Well-Known Member

    Yep, I noticed it on my last grow and became concerned and asked around. A couple of reputable personas responded it was natural, and more predominant a trait in Indica plants, which tend to have the lusher vegetation. As to why it happens, I'm sure Brick Top or UB could tell us. there has to be a scientific reason for it.

    benny blanco

    benny blanco Active Member

    Put your hand under the light by the new growth and see if its hot

    Serapis Well-Known Member

    If you read the actual post, the author states he took a temp reading of 24c at plant tops and lights are 24" away. I doubt it's heat.... but if tips are turning down or up suddenly, I think he should raise the lights 12" more and see what happens.


    vancitychopshop Member


    vancitychopshop Member

    bump. please check pics i need some advice guys. i raised my nutes and i see some improvement but still not sure what the problem is. turned my lights down to 4x600 from 4x1000w

    LowTimes Active Member

    Are you watering them enough? Flushing the nutrients regularly? Have you checked the PH?

    vancitychopshop Member

    ph is 5.7 i check it all the time. i just increased the amount of waterings and raised the nutes and it looks like they are starting to bounce back. the leaves are feeling more moist and some green seems to be returning to the leaves. I made the nutes as strong as i could. i am at 1140ppms which is 2.2 EC. hopefully this does the trick. im watching them closely
    jack ripa

    jack ripa Active Member

    I have had this happen a few times. Usually it's when I up-potted late and they are having a hard time getting the rootball fed. I have fixed it with a stiff dose of nutrients and I have also killed some strains doing the same thing.
    jack ripa

    jack ripa Active Member

    They don't look that bad. I would just flush them with a light solution next feeding and wait. They probably are having some mild light shock. Shoulda started them at 600 watts I think.

    vancitychopshop Member

    if they are stressed how long does it take to recover? is this going to seriously inhibit my stretching period? argh I have cut the lights down to 2x600w and i will see how they respond tomorrow but i have getting worried, by the end of the day the plants were seriously droopy and the leaves felt dry.

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