There are differences between traditional gardening and native plant gardening. One of the main ones is that native plant gardening encourages building a natural community of plants rather than showcasing individual specimens. In nature, there are combinations of plants that thrive on being intermixed with one another. For example, in NW Oregon where I reside, you will often find sword fern, oxalis, trillium, and vanilla leaf intertwined with one another.
There might be some scientific reasoning for these close relationships other than just preferring the same habitat and thriving together. It is known though, that this canoodling does keep moisture in the soil, and provides habitat for invertebrates and small mammals. Any dead material from plants decomposes directly in the soil providing nutrients. It also looks pleasing to the eye.
In traditional gardens, species are often planted farther apart (as shown below) and don’t interact with one another. This is to showcase them as individual specimens. Dead material is removed in the name of tidiness and then fertilizer is applied for nutrients. This type of garden needs regular watering. In a mature native plant garden, there will be minimal watering and no need for fertilizer. A little pruning is about all one needs to do.
To determine what plants do well with one another I have been making forays into natural areas with similar exposures, taking pictures, and making notes. Some books such as Real Gardens Grow Natives by Eileen M. Stark (a Pacific NW resource) provide associate species for each plant listed- valuable information when selecting plants.
In general, herbaceous plants should be planted a little closer than one would usually plant in a garden for the reasons listed above. Still, when plants are young there will be bare earth. It will take about 3 years to fully fill in.
I planted the first phase of my native plant garden last February. It has filled in some but still looks a bit naked. I have been advised BE PATIENT – hard for me to do. Taking a lesson from real life, communities take a while to build.