I planted 2 Dallas Blue ornamental grasses and another version (dont
recall name) last summer. The unknown one is a standard type, about
3-4 ft wide by 6-8 feet tall with cat tail-like flowers jutting out
higher than the rest of the plant at the top.

I need to know if there is a general rule of thumb on whether to cut
them both back in early spring, and if so, how much and when?

Thanks for any and all input.

Todd