Winter Crops in BC

I thought that Vernalization (a technique of tricking the seeds into thinking they have already experience winter by putting them in the freezer) was pretty cool. I also thought it was interesting that alot of the vegetables are sweeter after a frost, for example parsnips. I didnt know that it was actually beneficial to have plants in the ground over winter as then they can flower sooner and have stronger root systems. Last week we packed leaves to cover some of our plants that will be in the ground over winter. I wonder what variation there is between covering plants with straw or leaves or other insulators.