Echinops ritro Veitch's Blue

The selected form of the globe thistle, and the one carrying an RHS Award of Garden Merit. Deeper globes in a genuine indigo rather than steel-blue, larger heads, and a more compact habit than the straight species.

Whether the extra depth of colour matters depends on what you want it for. In a border, at a distance, the difference between this and 'Metallic Blue' is modest. In a vase, and particularly dried, it is obvious: the indigo reads as a solid colour where the paler form can look grey. If you are growing globe thistle mainly for cutting and drying, this is the one to take.

Everything else is as for the family. Rigid self-supporting stems at 90 to 120cm, thriving on poor dry sun-baked ground and sulking on anything rich or wet, hardy well below anything Britain produces, and mobbed by bumblebees for the whole of its flowering. It takes two or three seasons from seed to make a full clump.

Like all globe thistles, the leaves and heads are sharply prickled. Wear gloves.