A water supply is also a valuable consideration. Determine what type of soil you have. This is very important to know when you select the plants. It's a good idea to have the soil tested. The soil testing lab will gladly provide you with suggestions for improving soil fertility and drainage, if needed.
Some trees also produce flowers attractive to adult butterflies.
Step 3 - Choosing Your Plants. Larval food plants are those on which the eggs are laid and the caterpillars feed. Nectar plants provide nourishment for the adult butterflies. While it is possible to design a butterfly garden with only nectar plants, the number of butterflies visiting these gardens will be lower than those gardens that incorporate larval food plants. Generally speaking, the best butterfly nectar plants are those that are sunloving, purple, pink, yellow or white in color, and single-flowered rather than double flowered.