With long-lasting blooms topping an attractive dense clump of healthy foliage, it's unsurprisingly popular.

They don't like being divided either, so let them establish a nice dense clump.

It forms a dense clump of pointed leaves with purple flowers in spring, shading to a greenish-blue with age.

As noted, they usually prefer a location in a dense clump of grass or other very low vegetative growth.

This perennial grass forms a dense clump of stems up to tall.