Katy Perry has taken to Instagram to show off her new 'slime green' hair colour!

After dying her hair cotton-candy pink, purple and blue, K-Pez has stepped one step closer to a full rainbow by dying her hair green.

The Dark Horse singer debuted her new 'do on Monday (April 7), just in time for spring. It's not completely green - her roots and bangs are still her signature black - but it's definitely a big change-up for the California Gurl.

Writing next to the pic, Katy wrote: "SLIME GREEN FOR SPRING by my bb's @neeenaboo &@brantmayfield at the @mcmillansalon."

Perry has famously sported a bevy of bold hairdos, but what is it about these bright colorus that Katy loves so much?

"Of course, being Katy, she is a lot more edgy and she's cooler and she likes to take a lot of risks. And I love that she's like, 'I'm feeling a little blue, let's go blue' - not in her energy, just in her hair colour," Perry's longtime hair colourist Rita Hazan told MTV News back in 2012, right after the singer debuted her bright-blue locks.

"She's kind of this candy-coated sort of person. It's nice to see her experiment with different things."

Katy's new hair colour comes after actress Kristen Stewart's ditched her brunette locks for bright orange, with the switch-up though to be for a new acting role.