Isodon longitubus (aka Rabdosia longituba or Plectranthus longitubus)
Despite the indecision over the name, one of the absolute best late flowering perennials, with shoals of clear violet flowers over a long period from late summer and well into autumn.
The flowers really glow in the low autumn light like tiny violet blue gas flames. The camera never does it justice. Any soil in sun or semi shade. Easy but may not emerge until May or June.
sold out for now - more later in the summer
Closely related to the above, this one produces a profusion of violet flowers too, but in long slanting racemes.
The foliage is also unusual in shape and takes on pleasant tints as the season progresses.
May be late to appear in summer. Very few this year, but more next.
1L pots ~ £8
Quite different - this one has tubular pink flowers more like a Penstemon (some of which used to be classified as Chelone - hence the name) and foliage that reminds me a bit of a Hydrangea. This is a rhizomatous perennial, spreading steadily but not in a bad way. Usually grown as a woodlander (where it is admirable) but adaptable, and flowering over a long period.
1L pots ~ £7
Mauve pink bottle-brushes and large (to 6ins) fresh pale green foliage. A lush leafy herbaceous perennial related to Elscholtzia, Agastache and Rostrinucula, and with the same late flowering season - well into November if the weather allows.
Possibly best in sheltered woodland to avoid hot sun and early frosts which can damage the display. Otherwise easy and adaptable.
3L pots ~ £8