Most gardeners don't have good things to say about thistles. However, sea holly (Eryngium planum), also called flat sea holly, may change that opinion with its stunning steely-blue thistlelike flower ...

Sea holly is a striking perennial flower that displays purple-blue, thistle-like blooms from midsummer to fall. This easy-care plant has dark green leaves and thrives in dry, sandy soil with full sun ...