The Garden Community for Garden Lovers

In the shade

Gloucestershire, United Kingdom Gb

Do plants grow towards the light? it seems like they do BUT



All plants with green leaves need sunlight to photosynthsise, ie make food. Thus all plants with chlorophyll,the green part of leaves, tend to grow towards the major light source. There are plants which survive with lower light levels than others and these are the ones which enjoy a certain amount of shade. Often they have thin leaves which can absorb more light or leaves stuffed full of chlorophyll which can process the smaller amount of light available.

30 Aug, 2007


photosynthesise, Can spell, but not type.
Phototropism is the name given to the process of turning towards the light by the way.

30 Aug, 2007


Thankyou for your answer, but if this is so
Why is the grass so green
under the trampoline?

30 Aug, 2007


Because it is probably still getting enough light to remain so. In time it may well go yellow.

30 Aug, 2007


By yellow do you mean dead
Because when I move the trampoline
The grass dies instead.
And at the end of the day
It always leans the same way

30 Aug, 2007


Hi Again
My question really was serious, my reasoning may be sophistic, but it seems logical to me that there is an alternative, the alterative answer does not negate the answer given by Owdboggy as his answer on phototropism may be the trigger that sends the message to the plant first, if we look at the facts of the action, then the facts speak for themselves, don’t they? Just like the Sun going round the Earth as it does every day, rises in the east, and goes down in the west, then comes back up in the east giving another day (ad infinitum). Of course the heretic will say, that is not the case, we go round the Sun, and for saying so, I believe some were made to recant on the pain of death, well I have reason to believe that plants do not grow (lean) towards the light.
They actually grow away from the dark. I know you may think it is the same thing but the mechanics would be very different if that is the case.
I many cases we become so blinded by the blatantly obvious much like our car battery, on which there are two terminals one positive and the other negative and that is that. Yet, did you know in actual fact the positive is not positive it is negative and the negative is not negative it is positive, but the obverse became so well entrenched in the mind of the populous it was decided by the powers of the time not to change it over and leave it be, much like a plant growing towards the light. (?????)
I am very new to this gardening game most of my information has been gained from Mrs Green Fingers next door (over the other fence) so I tend to see things just a little differently from the conventional gardener due to first hand observation (some of it in the natural world frightens me, as we are all part of it, and susceptible to the observable vagaries)
What started my thought line was the application of weed and feed the weed part being an accelerant that induces rapid growth on broad leaf plants as I understand it, and so they burn them selves out, much like the dark induced rapid growth under the trampoline?
Consider a round bar (stem) when it bends it has a concave side and a convex side the convex side is the dark side so it must have greater growth than the concave side, or the concave side has retarded growth, “My plants do not bend they lean”. Yes that may be right but to cause them to lean the growth action would be lower down the stem near the root bowl an even darker place so the action would be the same, Hey! I’m not knocking any one just thought I would like to share some of my uninformed thinking on a subject I know little about.

30 Aug, 2007



That was mighty complicated and philosophical, bravo! ;-)

I am very new to this site, I just joined a few minutes back because I have some plants that I need to ID, and I wouldn't dream of trying to answer this question myself, but it has intrigued me.

I know exactly where you are coming from about the battery terminals, my electronics tutor (way back in my school years) was very surprised to find that I argued the point with him about the electrons in a circuit running from the negative to the positive, in the end we stuck to convention so as not to confuse my classmates! lol To be pedantic though, although the electrons in a circuit do run from neg. to pos. the current does actually run the other way, it's something to do with 'potential difference' and the exchange of electrons from the outer shell of atoms, but thats another story and if I get into the physics of it then we'll be here all night and i'll never get to my original thought on phototropism.

My take on this (and i've only been thinking about it for five minutes) is that the grass under your trampoline is probably adapting to the low light conditions and then being scorched to death by the new high intensity of the light when the trampoline is moved? Feasible? I'm not sure, but ficus are well known for being pernickity to move, any drop in light intensity can cause leaf drop, so maybe the opposte is true also? Sometime a plant will get so used to low light that full sun will make it shrivel and die?

As for whether plants move toward light, or away from the dark, that may be more of a philosophical question...if a tree falls and no-one is there to hear
You could test the theory, but it would take some specialist gadgets. Taking the assumption that the plant does in deed grow toward the light, specifically sunlight because that's the only way this works!, then we should ask the question, what kind of light is it that makes the plant grow that way? There are specific ranges of frequency (colour temperature) of light that are responsible for photosynthesis, this is known as 'photosynthetically active radiation' (PAR). For now i'll call them colours (so I don't have to type frequency :-)lol), certain colours of light are involved specifically with photosynthesis, others are needed for vegetative growth, still more others are needed to form flowers and fruits (blue and red spectrums respectively), and these vary from species to species. It stands to reason then that one particular range of colours will be responsible for phototropism, all you would need to do to find out (says 'all' like it's going to be easy! lol) is to grow plants under different spectrums of light (frequency tuned LED lights? very expensive I should imagine) and compare the way that they grow, or don't grow, toward the lights.
Eventually, and I haven't thought this out yet so I have no idea exactly how, by comparing the resulting data you could find that say, for instance, a colour temperature of 4600 kelvin is the colour that makes those plants dance, or alternatively you might find that the plant will grow toward whatever frequency of PAR light you throw at it, albeit in a stunted and sickly manner because it's not getting full spectrum light. This would lead to the conclusion that the plant IS actually growing away from the dark and it doesn't much care what kind of light there is, so long as there is some! lol You could even try getting it to grow towrd light that is not PAR, that would make the theory even more likely because the plant would be growing toward light that is of no use to it, hence simply growing away from the dark as it were.

I feel a 'the chicken or the egg' moment coming on here! lol
Which incidentally is the egg, because the egg would be the first mutation of the previous species which will grow into what we call a chicken, it's parents would be something else again, does that make sense? lol

It's late, and i'm rambling now! lol

Stewart. ;-)

4 Sep, 2007

How do I say thanks?

Answer question


Related questions

Not found an answer?