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Sunflower Seed experiment - unexpected result!

abigailannnicholsonabigailannnicholson Posts: 3
in Plants
I am a homeschooling mummy in need of some advice. I carried out a science experiment with my children whereby we planted x3 sunflower seeds, (giant sunflower seeds- mammoth grey stripe). We planted x1 in a propagator, x1 on the windowsill and x1 in a dark cupboard. The children made their predictions as to which would grow the best over a two week period - of course, they predicted the one in the sunlight would grow the best. Tomorrow marks the end of the two week period, and the seeds planted in the propegator and on the windowsill - show no signs of life at all. Whereas the seed planted in a dark cupboard has grown to a decent size. I have no explanation for them tomorrow and cannot find anything concrete online to explain this. I have attached a photo of the one seed that has grown taken today. If anyone could primarily offer an explanation for this being the only seed to grow (they were all watered at the same time everyday), and secondly - how to now ensure it grows best as we have finished this experiment now. Thank you!!
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  • GemmaJFGemmaJF Posts: 2,286
    edited May 2020
    Well that was fun science!

    I'm sure others will chip in, but this is a 'potted' explanation.

    I think the one in the cupboard was possible warmer and enjoyed the exclusion of light.

    So it germinated quickly.

    It then grew very tall and thin, due to 'etiolation' 

    https://en.wikipedia.org/wiki/Etiolation
  • GemmaJFGemmaJF Posts: 2,286
    Just as a little PS, if you have any seeds left, you can use the result to germinate new ones quickly, in the cupboard, as soon as they start to show, move them to the light for a strong solid plant.
  • strelitzia32strelitzia32 Posts: 758
    Also remember that every seed is different. They all contain different amounts of potential energy, different case thickness etc. So even 2 seeds from the same packet germinated under the exact same conditions can germinate completely differently. You can see this in any seed tray sowing, it's not uncommon to get a wide range of time for germination.
  • abigailannnicholsonabigailannnicholson Posts: 3
    Thank you for your comments. I have some talking points now when we talk about why that one has grown the way it has!
    So if I move it to the windowsill and transfer it into a bigger pot will it be likely to continue growing okay or the stem will be too weak now? 

    This is a first for us but would love to see them through to sunflowers if possible. :):smile:
  • GemmaJFGemmaJF Posts: 2,286
    edited May 2020
    Don't want to over complicate things, but pre-soaking the seeds for 12 hours and keeping them at a steady 18-20 c usually gives the best results with sunflower seeds. (though they can still be slow to germinate) I was wondering if the propagator and windowsill could have got a lot cooler than this at night?
  • abigailannnicholsonabigailannnicholson Posts: 3
    The windowsill would’ve have got cooler in the evenings for sure as we often leave the window slightly open. The propagator is actually a heated one so I was convinced we would see something happen with that seed first. 
    My youngest child was thrilled that something he had planted was growing so I will definitely have a go at planting some more of the seeds.
    When you say soak - do you mean in water? 

    Thank you again :):smiley:
  • GemmaJFGemmaJF Posts: 2,286
    abigailannnicholson said:
    Thank you for your comments. I have some talking points now when we talk about why that one has grown the way it has!
    So if I move it to the windowsill and transfer it into a bigger pot will it be likely to continue growing okay or the stem will be too weak now? 

    This is a first for us but would love to see them through to sunflowers if possible. :):smile:
    You might save it, the only problem is that it will have used a lot of energy from the seed to get to where it has. (so a couple of backup seeds put in the cupboard might be a plan). No need to move it to a bigger pot just yet, that might be too much for it (wait until roots have filled the pot). Try supporting it and see if it recovers in the light.

    The others may still also germinate, just taking a little longer than a couple of weeks.
  • FireFire Posts: 19,096
    Just checking the plastic cups have drainage holes in the bottom....
  • GemmaJFGemmaJF Posts: 2,286
    abigailannnicholson said:
    The windowsill would’ve have got cooler in the evenings for sure as we often leave the window slightly open. The propagator is actually a heated one so I was convinced we would see something happen with that seed first. 
    My youngest child was thrilled that something he had planted was growing so I will definitely have a go at planting some more of the seeds.
    When you say soak - do you mean in water? 

    Thank you again :):smiley:
    I agree, the heated propagator should have won! But with just one seed tested in each, it is like strelitzia32 says, natural variation comes into play.

    Yes just in water, soaking the seeds in a bowl of water for 12 hours before planting improves the germination rate.
  • strelitzia32strelitzia32 Posts: 758
    Depending how old your children are, this is a good opportunity to discuss the control of science experiments too, not just the "immediate" results.

    Your experiment is great, because you're trying to identify the impact of a set of conditions on seed growth. However for a more accurate result you need to eliminate as many variables as possible. For example, a seed in a cupboard vs a seed on a window sill has (at least!) 2 different variables - light and heat. So, although one seed may grow better you won't know if the cause is the light or the temperature difference, or both!

    Not only that, every seed is different because of the parent plant it grew from, the position on that plant, the nutrients it received relative to a seed right next to it etc. So instead of 2 seeds, you may want to try 3 seeds in the dark and 3 in the light, for a better sample.

    And we can go to the next level - the compost used, the exact amount of water given, the chemicals in the water (did you run the tap and thoroughly mix the water given to each seed, or did you run the tap then water then run the tap then water again). And so on!

    So this is a chance to introduce your children to logical, critical thinking.

     The absolute best science lesson you can teach is the scientific method and experimental testing.

    They will all sound really complicated, but it comes down to very simple principles: come up with an idea (the best way to grow sunflowers is in the dark), come up with a way to test it (grow a sample in the dark and a sample in bright sun), make sure your testing only changes one variable at a time (same water, same compost etc), have a control group (a sample in your house), be aware that your own personal bias might affect how you interpret the results (simply assuming "I think sunflowers like sun, so my results are because of sunlight", when actually the ones in sunlight did better because of a variable you didn't think of such as humidity or a dog or aliens!), and then record your findings (measure growth per day, characteristics of growth etc)

    Critical thinking is an invaluable skill!
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