There are all sorts of great reasons to grow native plants. You know for sure that they are hardy and adapted to local seasonal changes. Also, you can be certain they attract butterflies and birds in your area (flowers and fruit of some imported plants are of little interest to local animals). Finally, if they escape from your garden, they won’t upset the environment as can an escaped exotic plant can do, but will rather meld in. And that’s good. But the idea that native plants are more resistant to insects and diseases, often touted by well-meaning environmentalists with little actual gardening experience, is simply nonsense.
Some native plants have pests and diseases that bother them regularly, while others seem to have few enemies … but that’s also the case with introduced plants. Moreover, imported plants often have an advantage over native plants: a plant may have a pest in its native country that has not followed it to its new home. In fact, one well-known technique for controlling invasive exotic plants is to go back to their native land and introduce the pests that slow them down there.
I’m not saying to grow only non-native plants. But I do think you should know that at least one of the arguments used to promote growing native ones really isn’t valid.
If you truly want plants that have no major insect or disease problems, you have to do a bit of research on the plant itself. Assuming a native plant will have no pests is just ridiculous!