Tropical and Subtropical Plants by Hardiness
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Absolute hardiness by climate zone is extremely difficult to measure, because while two different plants may succumb at temperatures below 32F, one may survive fine in winter regions where temperatures regularly drop between 32-40F, while the other may decline and eventually die if temperatures stay between 32-40F for more than a few days. Nevertheless, knowing the absolute minimum temperature a tropical/subtropical plant can tolerate can still be quite useful, so below we have listed a number of plants, sorted by minimum climate zone.

Plants are listed by USDA zone (click for more information), with general winter temperature minimums. Also note that these are general approximations, and within any species, individual plants can vary in hardiness. Additionally, local microclimates can both virtually raise or lower a climate zone. For example, Cocos nucifera, the coconut palm, generally will not grow anywhere outdoors in the state of California, but in a few sheltered locations-near buildings coconut palms can be grown outdoors.

If you live in Zone 9a for example, any plant listed in Zone 9a or lower is a candidate for your yard.