Perfect geometric spheres of tiny florets, opening silver-metallic and deepening through blue-grey to a saturated steel-blue. The stems are rigid and silvery-white, self-supporting at 90 to 120cm, and the foliage is jagged in proper thistle style.It is one of the great bee plants. A mature clump in flower on a warm August afternoon is audible from several feet away, and the bumblebee numbers on it are as high as anything you can grow. It also dries better than almost any perennial. Cut just before the tiny florets open, when the sphere is dense and the colour is fully up, and the blue will hold for years out of direct light.It wants poor, dry, sun-baked ground, and it means it. On rich moist soil it makes soft growth, flops and loses colour; on a hungry gravel bed it is at its best. It takes a couple of years from seed to build a decent clump and it will not be hurried.It is a true thistle. The leaves and the dried heads carry sharp prickles, so wear gloves when you cut it or work around it.
