Gina1960 said: I meant that the heat tolerance was not what it means. The OP asked SPECIFICALLY about the Max Recommended Zone...the heat tolerance zone. They said they understood cold hardiness. Most people don't know the max heat zone, so they don't list it in their posts to the database.
The Max Recommended zone has nothing to do with heat tolerance per se, for what it's worth. There is always some confusion on this subject.
Let me try to clarify:
The Minimum cold hardiness in the database refers to the absolute minimum temperature a plant can tolerate without dying or experiencing significant damage.
The Maximum cold hardiness in the database refers to actual winter cold requirements, eg. plants that won't bear fruit or make flowers if they don't experience a certain amount of cold. It tells you the maximum zone (which again refers only to cold temperatures in winter) in which a plant will thrive or flower or whatever. Tulips and stuff like that.
For what it's worth, a lot of the Max zones listed in the database are not actually right, because some references end at zone 11 (or whatever) which would be the limit in the continental US. But Hawaii goes all the way to zone 13. So take max zones in the database with a grain of salt if you live in a subtropical or tropical climate.
I say this with a bit of twisted experience because I live in zone 11. You might think that is hot, but no, our annual maximum is usually just over 90°F. The zone 11 designation refers (only) to the winter temperature minimum here, above 40°F or so. Well above freezing. But our climate is not hot in any sense of the word really.
