Salvia Violet Queen

Dense erect spikes of intense violet-purple on sturdy stems at 45 to 60cm, and about as strong a natural vertical as any perennial will give you. Unusually, it flowers in its first year from an early sowing rather than making you wait until year two.

It is a genuine long-term plant. Hardy well below anything Britain produces, the crown expands each year, and a clump gives more spikes and better structure for a decade or more.

Cold is not what kills it. Winter wet is. It needs free-draining ground, and on clay it wants generous grit in the planting hole, a slight slope or a raised bed. That single decision determines whether it lasts.

Two optional tricks. Cut the developing stems back by a third in late May and you get shorter, sturdier spikes that flower a little later, which is worth doing in an exposed garden. And shear the whole plant to the ground when the first flush finishes in August; it regrows and throws a second flush in September and October, when a good deal else is over.