Stretching Seedlings

Discussion in 'Growing Marijuana Indoors' started by Calchin1994, Jul 9, 2019.

  1. Hi,

    A question regarding stretching of seedlings, as I am confused by this behaviour.

    So I germinated 20 seeds and stuck one of them on the windowsill, these seedling has grown normally, no stretching and looks very healthy. I was under the impression stretching happens from lack of light, however there is no way this natural light is more than my grow light?

    I have an Optic 4 LED light, very powerful at the manufacturers recommended hanging height. All the seedlings under this light however are stretching and do not look as healthy as the one on the windowsill. The temp is around 24 degrees with humidity at about 70%. They are both being watered with the same medium.

    Why are the seedlings stretching when I am sure they have more than enough light?


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  2. I'm not familiar with that light so I googled it.
    first question I have is which version did you buy? the 3000k or 5000k?
    with the stretch i'm guessing you have the 3000k. lower color temp is more red versus the more blue leaning 5000k. reds cause stretching. same as if you were to veg using an HPS light versus a MH light/ works, can be done, in fact i've gone seed to harvest with HPS light but it will stretch a lot - same as you are experiencing on your light.
    This time of year, the light coming in thru your window, even though it may be less intensive, is actually a better color temp than your light is for the phase of growth your plant is in. on the opposite end, when it comes time for flowering your 3000k light will be much better than the window because of it's intensity.

    at least that's how i'm reading it, I may be wrong.......
  3. Hi Smokey,

    Thanks for the reply mate:) the light I bought was actually the 3000 + 5000k one, which has two settings one for veg and one for bloom. I am currently using the veg setting which is why I am confused why this stretch is happening! Thanks for the thought though!
  4. Try lowering it? Hold your hand under the light and move your had closer until it feels warm on your skin or closer until it feels warm on your skin subtract 6 inches and keep your plants there risk of burn and gives them a little wiggle room to grow

    Sent from my SM-G965U using Grasscity Forum mobile app
  5. my apologies, i read the info much too quickly and assumed it was choice of color temp on the light, not both with a switch. that's what happens when you "assume".
    I hope you find the answer my friend. sorry i wasn't of more help to you.
  6. There could be more sunlight than you think.
    Full sunlight is over 100,000 lux, and overcast skies are a significant fraction of that.
    The grow light instructions usually recommend less than 10,000 lux for seedlings.
    I recently germinated seeds under full blurple lights, veg+bloom with seeds in RapidRooters, and there was no stretch.
    Seeds germinated under the same light, but dimmed down to 10,000 lux stretched a lot.
    I now believe seedlings can handle full lights if they are subjected to it before sprouting.
  7. This works with HPS lights but not with LED, too much light for a plant is a bad thing and the heat test does not work this way here

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