What is a nursery can? Just really curious. And how much larger is it than the plumeria pot? Sill you yank the pot or the can if weather gets bad? How will you address the roots growing out into soil? Thanks!

Nursery can is the black pots...I'm hoping it will help keep the roots cooler and let them do their thing underground.

I just did that for the first time this winter. I left 2 pots that were protected under larger plants plunged. It got cold enough to leave some tip damage on my large in-ground plumeria, but the smaller plunged pots were okay. Everything was covered with frost cloth as well.

It actually works well (at least in the Austin/San Antonio area) You will experience a bit slower spring but a longer season overall. My assumption for the delayed start is the ground temps are slower to warm than an exposed container. Conversely the roots keep warm into the late fall. Another good thing about this approach over planting/uprooting is you don't have to wrap the root ball or place in a container and it stands up by itself. Thus making winterizing your plants much faster.

I have often considered using a large hydroponic basket type of container, Something like a laundry basket with lots of holes in the bottom, as the inside container and then some sort of very large bin as the outside container. Then every year you only have to remove the primary root ball and can leave 60-70% of the weight in place. You can also replenish the soil mix as needed. An 8-10 ft. tall tree then only weighs a quite manageable 60lbs versus the whole 170lbs of container, soil and tree.

Unfortunately there really isn't a commercially available product which fits this description larger than about a gallon. I would say converting a laundry basket will work but suspect it will fall apart within a year or two as they are not made from UV stabilized plastics. Perhaps a soft side "Dirt Pot" type of grow bag would be an option but my concern with that will be how moisture it may trap and it will not permit roots to venture out past the liner.

Hope this helps.