Home » Roses are red – but they don’t need to be, if you know how to use food dyes and Fibonacci

Roses are red – but they don’t need to be, if you know how to use food dyes and Fibonacci

A rainbow rose
A rainbow rose. Photo by Ryan Amos

Valentine’s Day is here and unless you share the cynics’ view that this is a holiday invented by the flower industry, you might set off to buy a bunch of flowers for your other half on the day. Next time, why not do something completely different this year and create your own unique flowers?

The procedure is very simple (but requires planning ahead!). You will need white flowers and water stained with food colouring. Cut off the flower stems at an angle and leave them in a glass with the dyed water to soak up the fluid over night.

If you are a botany ninja and up for a serious challenge, have a go at creating a rainbow rose. Peter van de Werken (‘River Flowers‘) developed the technique based on his knowledge about plant phyllotaxy. Rose petals are arranged in a  Fibonacci spiral. This means that petal number one and six will be on the same vertical imaginary line. When you cut the stem vertically into four equal parts and transfer each end into a different glass with coloured water, the petals will take up the dye depending on their position in the spiral. Pretty, isn’t it?

“Rainbow Rose” reference: António A. Monteiro, Roberto Lopez and Jules Janick. “Gilding the Lilies: Rainbow Roses and Confetti Poinsettias“. Chronica Horticulturae – Volume 48, Number 1, 2008. 

Photo: Rainbow Rose by Ryan Amos. Licenced under a Creative Commons BY-SA licence.

Anne Osterrieder

Anne Osterrieder is a Lecturer in Biology and Science Communication at Oxford Brookes University, UK. A plant cell biologist, she loves the Golgi apparatus, lasers and cats. She has her own blog at Plant Cell Biology.


  • Great trick. Too bad my girlfriend likes only red roses! But I will think about this trick next year. It is something different and it can be a great suprise.

    What is interesting, I trade with Fibonacci numbers and use them every day to make my financial decicions, but I didn’t know that rose petals are arranged in a Fibonacci spiral.
    I know of course that we can find Fibonacci numbers in nature, but you have suprised me with that roses and Fibonacci numbers 🙂 That is why I will tweet about this to my readers 🙂

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