All you need to become a butterfly gardener is a sunny space, good soil, a little bit of hard work, and an assortment of nectar-producing flowering plants. If those plants happen to be native to Illinois prairies, wetlands, or woodlands, so much the better; the butterfly garden can become a personal biological preserve.
For those of you who are not merely content to watch the daily feeding rituals of adult butterflies, but instead desire a more intimate experience, food plants for caterpillars can be interspersed with the adult nectar plants. One can then watch diminutive "bird dropping" caterpillars slowly change into rough green snake mimics (the larva of the spicebush swallowtail), or observe the tiger-striped monarch caterpillar as it transforms into a jeweled chrysalis.
While we can't confine butterflies to our garden we can certainly lure them in with careful planning. It is best to locate your garden in a sunny area. Butterflies are cold-blooded and need sunlight to warm their flight muscles. When not feeding, butterflies like to relax in the sun. Flat stones or boards placed in and around the garden will provide ideal resting sites.
Wind and predators are the two most serious threats to butterflies. Although not much can be done about predators, planting your garden in a protected spot next to a vine-covered fence, a wall, or a windbreak of shrubs or trees will protect butterflies from summer winds.
To provide a cool drink for your thirsty butterflies, add a mud puddle, made from an old container without drainage holes that is sunk into the ground. These mud puddles provide important sources of moisture, and are as irresistible to butterflies as they are to children.
A final step before designing a garden is become familiar with the native butterfly fauna of your area, including their life cycles and food preferences. Check out Butterflies of Illinois: A Field Guide, manual 14 of the Illinois Natural History Survey field guide series.
Whether your garden encompasses several acres or resides in a few containers on the back deck, butterflies will be attracted if their basic needs are satisfied. Just as your garden grows, so will your knowledge and enjoyment of Illinois butterflies.