How can I save the rose? How to avoid the white mildew?

I'm doing the pot method to grow a rose cut steam and leaves are growing. However, I get a white mildew at the button of the steam that make it brown-black and it killed the steam on my previous try. I am also having the problem that I don't see the root coming out.


How can I avoid getting the white mildew?


How can I know that the steam is growing and the roots will come out?

How can I save the rose? How to avoid the white mildew?
Many people say to put bleach in water and put the rose in a vase, but im not really sure if thats true.......... Iv'e tried it on all kinds of flowers and it worked i wonder if it would work on roses.