Soils that hold less water are better for plants over-wintering. Soggy and cold is a poor combination for root health.

If you must over-winter outdoors, you can usually over-winter plants rated hardy to 1-2 zones colder than you w/o protection. If you bury the pots, or mulch heavily above ground, you can usually get away with plants rated hardy to your own zone. If you bury or mulch the plants out of wind against the N side of a heated building, you can usually over-winter plants hardy to a zone warmer than you.

Any other questions or areas you would like to explore?

Al

Al is correct...but keeping in mind that roots must NOT totally dry out...regardless of season. In my neck of the woods...we go months with no rain/moisture (even in Fall/Winter. You do not have that where you live...I don't think.

SOME roots can dry out completely. For instance, I overwinter geraniums by shaking off the soil, pruning roots and top, and hanging them upside down in the basement.

Al

Very much appreciate the sharing of your experience.

These are small, fixed cement pots that cannot be moved. They are in front of an elderly relative's zone 6 house, and often cannot be attended to.

I get to them when I can, but it's good they are very forgiving plants. Being snow-capped, or even freezing solid for a while has never been a problem. Air is quite dry in winter, but there probably would be enough intermittent rain or snow in a typical season.

Seriously considering changing them to a longer-lasting mix at the next repotting. (Being severely root-bound is about the only thing that seems to bother them.)

Thank you again.