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Do sunflower really move their flowerheads to face the sunshine throughout the mean solar day ? Are they really cross the Lord’s Day across the sky ? countenance ’s have a looking at what these beautiful plant are up to .
If you are concerned in more garden facts and folklore , also seePopular Garden Myths We ’ve All Fallen For .
As flowers form, sunflowers gradually stop tracking the sun.
Sunflowers and The Sun
Do Sunflowers Really Track the Sun Across the Sky?
Yes , sunflower areheliotropic — motivate in response to sunlight — but not the way we ’re often secernate .
Have you seen those pop garden memes depict sunflower flowerheads greeting the break of the day and gradually turning to watch the arc of the Dominicus throughout the day ? That ’s not exact .
The flowerheads do not postdate the sun , but , before the plant is blossom , the stems and leaves are antiphonal to lightness .
This heliotropic apparent movement only pass during the vegetative plant growth level .
How and why this happens is still debated . One of the best explanations involves hormones .
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Hormones and Heliotropism
Whatever part of the stem is in the shade during the day will also get the mostauxin hormone — what we also lie with asrooting hormones — triggering more growth than on the cheery side of the theme . In other words , the amount of development within one root word can be lopsided . And it ’s that maturation difference that tilt the stalk tip toward the sun .
And this is why sunflowers are only heliotropic prior to flowering — the disputation can only happen when the stem is actively growing and those internal secretion are change over around .
Once the works enter the reproductive stage — budding , flowering , and going to seed — the heliotropic movement stops .
relate : How to acquire Sunflowers ( & Common Mistakes To Avoid )
Sunflowers At Night
So what happens at night ? How does the ( not yet blossoming ) stem retort to its east - facing position by dayspring ?
This part involvescircadian rhythms , those national casual changes in metabolism or physiology that we all have , repeat roughly every 24 hour .
Without sunshine present , the auxin returns to where it was before dayspring . And that transfer the stem back to an east - facing position . As the sun rises , the outgrowth begins all over again .
Why Do the Flowerheads Face East?
If you ’ve ever seen a field of sunflower , you ’ve probably noticed the flowerheads all confront the same direction — often toward the eastern sky or close to it — and this does not change .
In my own garden I ’ve noticed that if the morning is block by a building or other obstruction , the flower will form confront whatever way provides first direct igniter of the sidereal day .
We ’ve see fields of dwarf sunflowers face up various directions including north , but sunflowers with larger head seem to be more Orient - centrical .
There are a number of unlike hypothesis about their final Lord’s Day - face emplacement .
Facing the morning luminosity , sunflowers may be more attractive to pollinators .
The sunlight may also facilitate evaporate sunup dew , reducing susceptibleness to fungous disease .
Or the affectionateness of the Dominicus might work more optimum plant temperatures .
These are all possibilities but we just do n’t have intercourse yet .
Summary
sunflower are heliotropic but it ’s only the fore that move and only during their vegetative growth stage .
Once bud and flowering , the flowerheads are stationary and usually east - cladding or close to it .
Related:12 Tips for Growing Giant Sunflowers
More About Sunflowers
Sunflower Podcast Episodes
More on heliotropism and sunflowers :
Some story of helianthus and interesting facts :
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Resources
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Sunflower Growing Tips
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