What to make of the ‘unresolved names’ from The Plant List? A bit of mix-match about the name of this one everywhere you look. Sometimes the basionym gives the best clue, in this case being: Veronica sachalinensis (Borissova).
All Veronicastrum look a bit the same, and probably many are familiar with the North American V. virginicum (Culvert’s root). In V. sachalinense the flower spikes seem to be even more slender. Just an image with the seeds for now… Beautiful, hardy, and it goes without saying, excellent pollinator plant.
Germination: sow in late fall, outdoors (cold/moist stratification).