Hi Marigold,
Sorry to barge in like this, since the weather is getting colder and drier(fall), it's probably best for your to grow them in an enclosed terrarium with artificial light and heat for your LL. If you have problem getting a heat sauce in the terrarium (can try those reptiles heat pad), try to place your terrarium near a heater until you get a desired temperature for your terrarium.
I was in Ontario, Canada during my Uni days, so I know how cold the weather can get in Michigan. I also kept some cps then, but nep can be problematic when they out grown the terrarium...