Cutleaf coneflower is the perfect 'back row' planting for your irrigated space. The sharply-lobed leaves and towering yellow flowers are a unique backdrop for our other moisture-loving species. Pollinators appreciate the late-season resources, and birds will like the seeds.
Some great tall companions include western coneflower, nettle-leaf giant hyssop, and fireweed. Then fill in the front with shorter species, such as black-eyed susan, narrow-leaf echinacea, sneezeweed, and streamside daisy.
Photo credit: <a href="https://commons.wikimedia.org/wiki/File:Coneflower-(Rudbeckia-laciniata)_(6232085309).gif" title="via Wikimedia Commons">Homer Edward Price</a> / <a href="https://creativecommons.org/licenses/by/2.0">CC BY</a>