Giant Ironweed has sturdy, upright stems and clusters of rich purple flowers from late summer into fall. Its strong vertical form makes it an excellent plant for the back of a native border or meadow. The arching seed heads add movement and interest from summer into fall. It forms attractive clumps and is generally well behaved. It spreads gradually rather than aggressively. It tolerates occasional flooding and performs best in consistently moist soil but can tolerate average conditions once established. You can divide established clumps in spring if they become crowded.