Best way to protect against frost and mold?

I have 14 plants outside and they are all just beginning to form clusters of hairs, they're done their stretch. So that means I have 7-8 weeks left of flower, ideally. So that would put me at the 5th-12th of October. So our first frost last year was the 20th of September, the nights are already getting cold. So I was just wondering what I can do to protect against frost and mold and allow my girls to go as long as possible? What can I use to cover them? Has anyone tried the sprays?

Some frost is good. But, with that said...

Use large bags at night and cover them. Also, water the ground the night of a frost to keep the roots working and energy going through the plant. I'm a Wisconsin boy. I went through a few frosts last season, amd was still harvesting my last plant first week of November.
Snow changes everything, of course.