Reading various threads here, I know that plants are not considered to be sentient beings in Buddhism. But I still can't help wondering whether Buddhists create bad karma if they cultivate non-native plants. By 'cultivate' I mean for example planting a palm tree in a temperate climate (with large temperature changes over a year) or a giant sequoia anywhere but in the Sierra Nevada mountains in California. (I do not mean caring for plants that have been planted by others before me.)
Unwholesome actions are created when the intention/volition behind the action is unwholesome.
If one is cultivating plants with intentions of greed, anger, non-harmlessness, then one is creating unwholesome kamma, which will produce unwholesome future resultants.
If one is cultivating plants with wholesome intentions such as good-will, caring, altruism, wholesome future resultants will be produced.
What is important here, is the Mind that is behind the action. Everything starts in the Mind, with reference to the twin verses in the Dhammapada.