Bob, I dig up my s. guaraniticas each year. I repot each one into 3 - 5 gallon nursery pots & plunge into another larger container. Bark fills in around the sides & then about 8" of autumn leaves on top. These are placed along the back of my garage -- lined up under the eaves, which offers protection from the wind & rain. (I'm near Seattle - we get lots of rain.)
We were forewarned about lows -- mid-20's -- for this week. So, I bent wire fencing, inserted it into the larger containers to offer support. On top of that is draped an old thick blanket. Normally, I don't need to add the extra protection, but we've not yet had a frost in my area - nighttime lows went from mid 40's to mid 20's in one 24 hour period.
The nice thing about overwintering for the next growing season is the root system is already larger, so the plant has a jump-start. My area is considered zone 8, but because of all the shade from the very tall trees, it acts more like 6 - 7. I overwinter as many plants that will fit on a table in the garage; these are set on trays inside cardboard boxes. Usually don't need any bark, but when I get a nice haul of dry leaves, I use those for insulatory purposes.
