would putting bags of soil, that may or may not be contaminated with something like grub worms, or spider mites, ect. into a freezer for a length of time, kill off the infestation(s)?
Freezing likely won't work, and don't freeze your beer either I used to solarize soil by putting it in thin layers between clear plastic sheets and let the sun sterilize it. Now I just make sure my "soil" used indoors is a good quality/sterilized product
Lots of people do not like Miracle Gro. I had to buy some - there was no other choice and a "white death" that was suppose to shut the city down for a couple of days was predicted. Found a nice size rock in it:
I generally don't sterilize new dirt, but if I reuse old stuff I microwave it for 2 minutes on high first. As others state you are also killing beneficials.
Nuking it really is the best easiest quickest cleanest way of killing everything in dirt.