It's simple. Hold down the mouse to grow the stem, and once the stem is fully grown, click on it to grow a flower :) EDIT: It's actually 90% pen because of the backdrop and the mouse detector sprite.
My first pen project! This was quite fun to code, because, since this is my first pen project, I learnt a lot about how to use pen. Special thanks to @Dairop for their Pen Tutorial, I couldn't have made this without it. Here: https://scratch.mit.edu/projects/249886667/ UPDATE 23/05/19: Backdrop is now drawn in Pen :)