The ‘Dragon’s Head’ is an interesting group of perennials with various shades of attractive bluish purple flowers. It is more commonly grown by rock gardeners. Some books have warned that this is a highly invasive group of plants. I believe only some of the Dracocephalums behave badly.
I am not certain that this plant of mine is correctly identified as Dracocephalum argunense. Some Dracocephalum species are very similar, and are difficult to differentiate even by experts. I believe I sowed them from seeds many years ago, and forgot where the seeds came from. This is one of the earliest names registered in my database. It is not invasive at all, and has a nice bluish lilac flowers. Its low creeping growth habit is more suitable for rock garden context.
One of my plants is from a mail order source, and the other is from seed obtained via Ontario Rock Garden Society. It has much larger leaves and flowers than my other Dracocephalums. My respected perennial reference book cautions that this is a very invasive plant, but so far, after 3 years, it has not made a move. The active vole population in my rock garden may have something to do with that.
This is probably the most attractive Dracocephalum I have. The flowers are much smaller but profuse and delicate looking. The only problem is that it self-sows wildly. However, with such beautiful flowers, I am willing to put up with that. I must be careful to not grow it near any location that is difficult to weed.
This is the first Dracocephalum I acquired. It had long been eaten by voles. Although this is the name that came with the original label, I have difficulty telling the difference between this and Dracocephalum argunense. It is very difficult to find any information about this species in any of my reference books or the internet.