Yarrow

Yarrow comes in a few different colors, though I am partial to the pinks and reds. There are white ones and yellow ones as well. When they're not in bloom, they stand about 6-8 inches tall, and the blooms can reach about 2 feet. They do not need super-rich soil, so they're perfect for here! Plant them in the sun and be prepared to keep them in check, as they do enjoy spreading out a bit. You need to remove the blooms when spent. I typically cut the whole plant all the way back when they finish blooming. It's not necessary, just a time saver.

Fun Fact: Yarrow leaves help activate compost.