Gardening for butterflies is a lot different than gardening to attract bees to your garden in Chicago. Butterflies need two kinds of plants; host plants that butterflies can lay eggs on and the caterpillars can eat on and nectar plants that butterflies can feed upon. To be honest, I never set out to attract butterflies to my garden, we both just happen to like the same kinds of plants. The following is a list of plants that I've noticed attract a lot of butterflies into my garden in Chicago.
I don't get a lot of Monarch butterflies in my garden but when I do they are usually visiting the zinnias, a common garden annual that is easily grown from seed and not too expensive when purchased at the garden center.
Purple Coneflowers are another big draw in the garden. Here a Black Swallowtail is feasting but these are usually the place to find Red Admirals. Purple Coneflower is a perennial that responds well to deadheading and provides a good food source to the butterflies late in the season.
Other plants that attract or host butterflies that you can find around Chicago include:
Queen Anne's Lace
Look around your neighborhood and see what butterflies are already being attracted to the gardens and plants. Don't turn your nose up at the "weeds," some of them do the best job of attracting butterflies.
Note: If you're aim is to attract butterflies into your garden you will have to give up chemical sprays because they can kill caterpillars and adult butterflies. You can also set out certain fruits like sliced oranges to provide much needed sugars and shallow dishes of water for the thirsty butterflies.
Here's a video I made and uploaded to YouTube two years ago.
It shows some Red Admiral butterflies on my Purple Coneflowers, and as you can see they aren't very skittish. They are said to be the most people friendly of all the butterflies and because of the way they land on me when I'm out in the garden I'd have to agree with that statement.