Plant Hormone Simulator
Dial up auxin, gibberellin, cytokinin, ethylene and ABA and watch a plant bend toward light, stretch taller, branch out, ripen fruit or drop its leaves.
Bend angle (blue, degrees) and fruit ripeness ×80 (red), vs simulated hours.
About the Plant Hormone Simulator
Free plant hormone simulator. Dial up auxin, gibberellin, cytokinin, ethylene and ABA and watch a plant bend toward light, stretch taller, branch out, ripen fruit or drop its leaves. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for botany, the plant hormone simulator runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Dial up auxin, gibberellin, cytokinin, ethylene and ABA and watch a plant bend toward light, stretch taller, branch out, ripen fruit or drop its leaves. Use it to explore botany ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Plant Hormone Simulator
- Use the controls to change Auxin (IAA), Gibberellin, Cytokinin, Ethylene, Abscisic acid (ABA), and more. The simulation reacts instantly.
- Press "Reset plant", "Reset to defaults", "📄 Lab Report" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Move the light to one extreme and raise auxin, then watch the bend angle readout.
- Raise cytokinin and drop auxin, and watch new branches appear.
- Raise ethylene and watch the fruit ripen and the leaves yellow, then raise cytokinin to slow the ageing.
- Try the 30-degree bending challenge with ABA kept low.
Key ideas you can learn
- Auxin builds up on the shaded side of a shoot and makes those cells elongate more, curving the shoot toward the light.
- Gibberellin drives stem elongation; more of it makes a plant grow taller faster.
- The cytokinin-to-auxin ratio decides whether tissue grows more shoots (high cytokinin) or more roots (high auxin), the same rule used in plant tissue culture.
- Ethylene triggers fruit ripening and leaf senescence, while cytokinin actively delays that ageing.
Where this is used in the real world
Farmers use synthetic auxins as rooting powder and weedkillers, gibberellin sprays to elongate seedless grapes, and ethylene gas to ripen bananas and tomatoes after shipping.
Who is this simulation for?
Students, teachers and curious learners of all ages.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
How does auxin make a plant bend toward light?
Auxin accumulates on the darker side of the stem, making those cells elongate faster than the lit side, which curves the tip toward the light.
What decides whether a plant grows more branches or more roots?
The ratio of cytokinin to auxin: more cytokinin relative to auxin favours shoot and branch growth, while more auxin relative to cytokinin favours root growth and suppresses side branches.
Is the Plant Hormone Simulator free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Plant Hormone Simulator work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.