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Thread: Why do my seedlings stretch?

  1. #1
    420 Member SmokeyMacPot's Avatar
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    Why do my seedlings stretch?

    Seedlings stretch due to the influence various factors. In other words the way the genotype is expressed is determined by the biotic and abiotic factors affecting its growth. The site where the plants are grown may be conducive to stretching due to a nutrient deficiency or other factors like temperature or day length.

    The source of the seed is also important. If the environment that the plants were from originally was consistant from year to year (for instance, indoors) and/or encouraged stretchy plants (crowding), natural selection may have passed on the trait for stretchy plants. If the seeds were from hybrid plants that were crossed "Willy-nilly" the variation of the offspring will blur the distiction of phenotypes.

    When plants stretch due to competition for light, this is known as the "shade avoidance response phenotype" (SARP). The light reflected off of other plants has less red in it because the leaves of the other plants absorbed it already. This is how the plant knows how close it is to its neighbors. When there is less red, the plant stretches so it can compete better for the light. HPS lights are high in red spectrum, so plants grown under them stretch less.

    Plants match their phenotype with the environment, but this can depend on other factors. Temperature and photoperiod can affect the response to red light by limiting which phenotypes are expressed. Higher temperatures, shorter photoperiods and dense planting make the plant more sensitive in its response to the amount of red.

    The SARP is really an interaction between abiotic factors and the quality of light. The size of a plant that has stretched may be larger than a plant grown under a full spectrum, but overall yield will be less. A plant grown under a short photoperiod is more sensitive to red, but a plant with a long photoperiod period will stretch regardless of the spectrum because it has time to make a longer stem. In fact under longer photoperiods, the plants become less sensitive to red because seedling elongation affects the health of the adult plant.

    The seedling is aware of it surroundings. The SARP isn't affected by photoperiod in a seedling because the seedling has to be aware of the density of the population, but if the day-length is short enough to induce flowering, then they will stretch. An elongated plant costs more to grow because your growing more stem and less bud. So under conditions of dense planting the temp and the photoperiod determne how close to plant to minimize stretching.

    Authors: MR_NATURAL420

  2. #2
    420 Member MrsLonely's Avatar
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    Re: Why do my seedlings stretch?

    Is there a way to stunt the stretching of the seedling? Mine seemd a lil 2 tall already.
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    Re: Why do my seedlings stretch?

    Hey MrsLonely, the only way I know how to stunt vertical growth in seedlings is by moving your lights closer. If you cant do that, move the seedlings closer to the lights. If your using HPS' then i wouldnt suggest doing that as they emit waaay too much heat to be that close to the actual plant. Hope this helps

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    Re: Why do my seedlings stretch?

    How far away should they be if I am using a 400watt m.h. light. my seedlings sprouted 2 days ago?

  5. #5
    420 Member braynes's Avatar
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    Re: Why do my seedlings stretch?

    Quote Originally Posted by Grandpappy Sr View Post
    How far away should they be if I am using a 400watt m.h. light. my seedlings sprouted 2 days ago?
    I do not think you should use a 400mh light that soon,you can not get in close enough to not prevent stretch.
    br

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    Re: Why do my seedlings stretch?

    After seedling gets to about 6-8 inches and looks more like a plant not seedling I FIM the Top and it slows the up growth and cause the side branches to grow... I usually wait longer then that but if I have a plant stretching too much it works for me to slow it down and let the rest catch up.

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    420 Member IGrowGrass's Avatar
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    Re: Why do my seedlings stretch?

    light too far away

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    Re: Why do my seedlings stretch?

    My plants always stretch early

  9. #9
    420 Member rattlerr's Avatar
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    Re: Why do my seedlings stretch?

    Plants normally stretch when they are reaching for the light, from what i have read and studied. You should keep the light between 1 foot to 18 inches above the plant depending on ventilation to move heat.

    I have 96,000 Lumen of Sun Blaze T5 HO and keep my lights 14 inches above my plants. I also have my plants receiving light from 4 sides "Top,Back,Left & Right" leaving the front open for work and air movement.

  10. #10
    420 Member jambo stoner's Avatar
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    Re: Why do my seedlings stretch?

    lower the lites 2 about 12-18 inches above plants, it helps to stop stretching during the seedling stage

  11. #11
    420 Member 68camaro's Avatar
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    Re: Why do my seedlings stretch?

    bend it to slow the streachin, easy does it though no stress and you shouldnt be able to tell you bent them at the end of the day. it will blow your mind i guarantee you!!! bend it dont top it!!!! it does all kinds of things!!!!
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  12. #12
    420 Member QUEENBUD00's Avatar
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    Re: Why do my seedlings stretch?

    them plants,when grouped together stretch to get more light the bigger ones take what they want..you either give them more light or rearange them.....or put them girls outdoors...

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    Re: Why do my seedlings stretch?

    ok i have a ?, why hasent anyone done a discution on watering as a seedling, my first seed poped threw the soil and im not sure how much or when to water it, running CFL's got light about a foot or so from plant it jumped threw the soil 2 days ago, im not sure how much water to give it at this young an age eather, any help would be awesome

  14. #14
    Welcoming Committee - Member of the Month July 11' Captain Kronic's Avatar
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    Re: Why do my seedlings stretch?

    First off... welcome to 420 mag forums, roll one up and chill!

    Secondly, if you look, there are many thread and articles here that cover that exact thing and more!
    Here is a thread that is directly above this one!
    How to Grow Marijuana - 420 Magazine

    EG:
    Germination & Techniques
    How Do I Germinate Seeds?
    Preparing Seeds for Easier Germination
    Is There a Faster way to Germinate Seeds? (Scarification)
    How Do I Germinate Seeds in Soil?
    What is an Idiot Proof Way to Germinate Seeds?

    Germinating Cannabis Seeds (for Bio Growers)
    Vapour's Rockwool Germination Technique
    Vegemite's Seed Germination Technique (Rockwool)
    KiDKiND's Germination Technique
    Joe's Seed Germination Technique (Rockwool)
    How Do I use Oxy-Plus for Seed Germination?
    The Germination Process of a Dicot Seed
    Soil Germination Problems
    When I am tending seedlings, I usually check them twice a day. You should be able to tell what they need, by the look of the soil and also by the weight of the container you are using... test this by watering them sufficiently, till water dribbles through and then pick it up, you should have a pretty good idea when they need more H20.

    Chances are if you temps and or air flow are right, you may need to water daily... I do!

    Also, if you are using a nute free soil... once they get into veg, a couple sets of true leaves, give them a diluted flowering nute to promote root growth!

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    Re: Why do my seedlings stretch?

    i am using soil that you get at walmart for cattis type plants. crosses fingers thats good i hope, im still really new at this whole thing i just wasent sure with the seedlings i have been on here almost daily to read up on stuff. for my seedlings i am useing a plastic cup with soil the seedling is sticking out about an inch or so, i just have been giving it a little water here and there, when i feel it and it feels to dry to me, my 1 CFL is about a foot or maybe a little more away from it, i am using my closit it has a nice air flow, it seems kinda cool in there, but under the light it is very worm, getting more lights in a few days, useing 100 watt light bulb
    Last edited by superfly; 05-27-2011 at 03:01 PM. Reason: for got to say thankyou lol

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