Whenever the foliage dies back is good, before you lose track of where they are. I put them in an open plastic bag in basement, with a lot of dirt still clinging on (when I lived in OH. Hardy where I am now.)

Hi

Are they florists or species glads.?? I'm in s. florida so mostly winter for me

Would think Minn would be excellent for summer!! Not so hot and humid.

I force mine into summer dormancy by witholding water after flowering

In your case I'd wait until a light frost which would assure they go dormant and have stored all the nutrients they can get .If they go dormant on their own dig and store in a cool dry area . I find florists types store poorly so I usually just buy new ones come winter Species types no problem.

gary