perry230.jpg Let's hope RiRi knew her friend was going to be so candid!

Katy Perry covers the October issue of Elle Canada, and the singer spoke candidly about her friendship with Rihanna and how envious she is of her pal's ability to look beautiful and refreshed despite her hard partying lifestyle!

    "I think Rihanna always looks so fresh and I'm like, 'How do you do that?' We all know how much pot you smoke! And you don't sleep because you're on Instagram at four o'clock in the morning," she joked to the mag.

The chart topper, whose latest album Prism is due for release on October 22, then goes on to tell the glossy her thoughts on aging and maturity.

    "I'm 28, and I don't know how young you are, but, as you must know, when you're at the end of your 20's, it's a very important growing time. It's called the Saturn return, if you like astrology - I know it's important for me," she added.

Sounds like she's all grown up and ready to roar!