Native Plants are Not Less Prone to Pests
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 will not disturb the environment as can an escaped exotic plant can do. And that’s good. But the idea, often touted by well-meaning environmentalists, that native plants are more resistant to insects and diseases is simply nonsense.
Some native plants have pests and diseases that bother them annually, while others seem to have few enemies… but that’s also the case for introduced plants. Moreover, imported plants often have an advantage over native plants: a plant may have a pest in his home country that has not followed it to its new home. In fact, one technique for controlling invasive exotics is to go back to their native land and import the pests that slow them down.
I’m not saying to grow non-native plants. But I do think you should know that at least one of the arguments used to promote growing native plants really isn’t valid. If you really want plants that have no major insect or disease problems, you have to do a bit of research on the plant itself, not to rely on its place of origin.