Alex, with any of my cacti, I try to really make the media as gritty as possible, so aside from using cacti mix, I always add more pumice or perlite. Really rocky media to protect the base of the plant. It can easily go rotting, and I do not recommend fertilizer when cacti is dormant, no use for it. To be honest I do not feed my cacti, I would rather repot with some fresh media as needed when it is mid Spring.
Good luck on your plant! Please keep us posted how it goes!
