Butterfly Garden Shelter
Perhaps the first consideration in planning your butterfly garden should be how to shelter the garden. Butterflies, as you can imagine, are not creatures that do well in the wind and, in most cases, prefer protected areas full of sunshine. During the construction of your butterfly garden, providing this protection is your main concern. Yet there are some species that prefer the woodlands and if your area has such species, you may wish to insure that trees of the proper variety are made available for such.
If the location of your butterfly garden allows, it would be most advantageous to be south facing so as to capture as much sunlight as possible. Then add some type of flanking wind breaks, be they in the form of a fence, rock wall, or shrubs and trees that can also provide food and hiding places. This need not be a totally enclosed area but if space allows, you may wish to consider this, always provided the area does receive plenty of sunshine.
Barbara Damrosch in her book Theme Gardens offers the suggestion of the cellar or foundation of an old house as a spot that would make a wonderful butterfly garden because of the shelter it provides from the wind. I suspect this type of potential garden area is more readily available back east than in the West where I am. But just think of the interesting sunken garden you could make in such an environment.
On the whole, however, the main objective is to provide a windbreak across the direction of the prevailing wind in your area. In mine, the wind normally comes from the west, be it the northwest with a cold front coming through or the southwest with a low coming in from California. As such I would definitely place a windbreak on the west side of any garden in this area.