Thank you for your question to Extension. The Butterfly Bush is controversial. On one hand, it is a pollinator and listed in the U of MN Extension website for a choice to attract adult butterflies in a garden. Here is the link:

Creating a butterfly garden | UMN Extension

But it is also considered an invasive plant to many of our native plants, crowding out desirable plants. Here is a link to a Penn State Extension article that recommends not planting Butterfly Bush:

Avoiding Invasives: Butterfly Bush (psu.edu)

The decision to plant is yours after you take into consideration the pluses and minuses of planting. It would depend on your yard, current plantings, and if you are looking for a truly native planting. Good luck in your decision and happy gardening!

Thank you for your question on planting a wildflower mix. It's good to hear about people who are dedicated to planting wildflowers and grasses (instead of a green lawn). Pollinators, including bees and butterflies will benefit. You can seed in mid-October if you plan to wait until fall; the spring planting time of May/June has already passed. Here is an Extension article about planting wildflower and grass seed with great directions:

Planting and maintaining a prairie garden | UMN Extension