The essence of zone hardiness has to do with the plant's tolerance to penetrating freezing. That means how the above ground parts of the plant, including its vascular system and the nodes that will generate new growth withstand both penetration of cold and frequency as well as intensity of thermal cycles. This also applies to below ground parts, which are protected by the ground as an insulator up to the point, depth, and duration of frost penetration.

You will need to know about your microclimates, especially exposure to freezing and drying winds, soil drainage, and soil fertility, including pH (acidic to alkaline).

Most plants that would say hardy to zone 8 doesn't mean they need the cold, since the minimum temperatures refer to the chances of a small number of instances where the lows reach the stated temperature. These figures for a minimal cold tolerance won't work with winters like this last one, and erratic weather patterns will take their toll on plant growers everywhere. It needs to be said that gardens are the canary in the mine for native plants in general, since damage to the this flora does take place, but is not as obvious.

Moving potted plants into a cellar, shed, or garage will become necessary for unusual conditions, as well as mulching beds, covering special plants with cloches.

If your problem is sustained or heavy rains, use raised beds.

Even this can fail. A lot of my friends in Baton Rouge and New Orleans lost plants in raised beds because of sustained high water, which saturated raised beds continuously because of capillary action. Southern Louisiana near the Mississippi River is close to sea level, with really huge levees, which means water retreats slowly after long rains.

There is only so much you can do, so it is important to assess your environment to determine what is possible and draw go/no go lines. Anticipated frequency of unusual events is one of those areas.

Thanks, Rich. I figured you'd respond and appreciate your expertise and wisdom.

Along with what you say, the question becomes how much one wants to invest in trial and error in these troubled weather times, with almost ensured disappointment sooner or later.

Such is life.