Butterfly Weed Treatment Plant butterfly weed in late spring after the soil warms. Don't assume it to bloom the main year; flowering could just take a few decades. Blooms last about two months, from late spring until finally late summer season. A. tuberosa It’s also a bunch plant for Monarch https://is-milkweed-an-annual-or97530.blogdon.net/facts-about-butterfly-milkweed-annual-or-perennial-revealed-47104890