What is that you say? Have you ever gotten those great catalogs in the mail with page after page of pretty flowers or exotic fruits and vegetables? And you think "wow, that would look so awesome in my yard!" Usually somewhere in the fine print of that plant's description is something like "Zone 5". This means it's ok to grow in all zones to Zone 5. If you're in Zone 10, that plant probably isn't going to do well. So those pretty plants you see in the catalogs might do wonderfully up North where it's not so hot, but might not do well down South in the hot summer. Don't order the plant if it's not going to do well in your zone.
There are so many factors that can impact your plants. Most importantly are the temperature extremes in your area. What is the hottest it gets? What is the coldest? Does it freeze? Are the extreme temps long lasting or short lived?
What about annual rainfall? That can affect plants. Some
don't like "wet feet" and if you're in an area with a very high
annual rainfall total, you'll want plants that like that.
One of the best websites I've found that narrows much of this information down, is this really cool interactive website. You just put in your zipcode and hit enter and you can get all sorts of good information about where you live. Sometimes you have to just do some googling. My favorite search term to use is "best PLANT for LOCATION". For example, I might google "best pecan tree for Houston Texas". That narrows your search down to things that are more appropriate for your area.
This website that they put out, has great info for those of us here in Texas.
So what is "native planting"? Simply put, it's planting the plants that are normally found in your area. Those plants that will do best. If they have grown in your area forever, they are going to be great assets to your yard. This may apply more toward, perhaps, landscaping type plants, though there are native fruit trees, native nut trees, native flowers, etc. There are rarely native vegetables, but there are vegetables (and herbs) that are better adapted/suited to different climates. Just do your research to see what works best for you. If you decide you want to grow, say, zucchini, find out which one does best in your part of the world. That's what horticulturalists do best. They cross different varieties to come up with one that is better in a hotter environment, or colder, or wetter, or drier. A 'native plant' is going to give you the best shot at an easy to care for, long lived, nice plant for your yard. Bottom line, as with most anything, don't just buy the first plant you see, be it online, from a catalog, or in a store.
Remember this little tip: If you shop at a big box retail chain's garden center, chances are you are going to get just a generic variety of plants, probably the same plants at the same store in the next state over. Think about it; they can't ship different plants to different cities in different states. They are more apt to load a truck with plants from one supplier and ship to all the stores in a given region. You will probably get a generic plant that might or might not do well. A better place to find plants for your zone is to find a local garden center/plant nursery. They will be more likely to stock plants better adapted to your area. Not to mention, you can ask questions of someone that would be more apt to have the correct answer.
Thanks and happy researching and happy planting!!!