This is cutting ageratum, not the ground cover type. This variety (Tall Blue Planet) grows up to 18" tall so it has long enough stems for bouquets.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/62528187@N00">Dwight Sipler</a> from Stow, MA, USA
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/photofarmer/3797170833/">Ageratum at small farm</a>