The most popular colors for flowers tend to be purple, lavender, and pink. But to attract the widest variety of butterflies, a variety of colors is best. Butterflies may also see colors in flowers that are not visible to humans. Mass plantings of a flower are more attractive than just one or two of each. Fragrance in flowers is also important.
Butterflies have an excellent sense of smell.
Use older varieties with more scent rather than hybrid varieties which may be milder in odor. Adult butterflies may live from two weeks to several months. Usually, butterflies lay eggs and become caterpillars that feed on a plant different from the one on which the adult feeds. These host plants can be weeds, or nearby trees, so you don't necessarily need to supply host plants. Only a few butterflies have a caterpillar which is actually a pest.