It would be most helpful if people could avoid specifying a maximum zone for most plants unless those plants actually require winter cold to survive (or fruit or whatever). In my zone 11 experience these maximum zone recommendations are proved wrong a lot of the time and simply represent errors propagated in the echo chamber of the internet.
To be perfectly clear with an actual example: a plant with a maximum zone of 9b should require temperatures below 30°F in order to survive or be productive. If the plant does not actually require those freezing temperatures, please do not specify a maximum zone.
In the case of many plants, a maximum zone requirement (say zone 11, which is specified for many plants) would preclude them from being good house plants except where winter temps hit 50°F or lower inside, which isn't going to happen where there is climate control. The number of plants currently in the database with both "house plant" and "max zone 11" specified (a contradiction in most situations, in my view) is currently too great to be displayed on a simple search. But here are 30 plants which apparently require freezing temperatures and yet magically still work fine as house plants:
https://garden.org/plants/sear...
When in doubt, please do not specify a max zone. This is more likely to confuse people and propagate errors than it is to provide useful information.
