Ice is an entirely different matter. Ice doesn't have the insulating effect as snow since there are no buffering air spaces. As the water freezes, it releases heat. As soon as the water application ceases, the protection disappears also. There are a few factors, that we as gardeners can control.
Some plants tend to continue growing, despite cold temperatures and reduced day length.
We have all heard about not pruning some shrubs in late summer and fall. This is because some plants respond to pruning with new growth which is quite tender, and is easily killed since it has not become acclimated to the cold temperatures. Just like parents and their kids, offspring bear some resemblance to the parents. Plants are similar, in that seed taken from a tree in Minnesota will be more cold hardy than seed taken from the same type of tree in Florida. Conversely the plants from the Minnesota seed source might never break dormancy in Florida, due to the lack of cold.