Leave flowers in a vase containing highlighter fluid and shine a UV light, and voilà!

Holy shit that's amazing!

Ooh I wonder if different colors would work!

This doesn't actually work guys, sorry to say. you can youtube it and many have tested it, sometimes the uv shows up in the flower but by the time they soak it up they are so wilted they look like crap and the uv looks nowhere near like this photo :/