One of the glories of September are the blooms of late-flowering gentians. Their colours are astounding, wowing in varying tones of iridescent kingfisher blue to deep, brooding cobalt, which in some varieties is additionally lined or splashed in white. There are few pure white forms that have either been obtained from the wild, or specifically selected or developed by enthusiasts, along with a few pink forms, but these miss the true brilliance of what autumn gentians are all about.
The most well-known species is Gentiana sino-ornata, which was found by plant hunter George Forrest in Yunnan, China in 1904, and again in 1910. The plant produces a mat of creeping stems which become covered in bright blue 7.5cm (3in) long trumpets in sun or very light shade. These autumn-flowering gentians need acid soil, preferring some moisture, but not constantly wet conditions. If your soil’s chalky, but you want to try these plants, don’t despair as they can also be grown in pans or troughs of ericaceous compost, but don’t forget to keep them watered, ideally with rain, rather than tap water, especially in hot or dry weather. Their breathtaking flowers are worth all the effort.
There’s only one oddity, the willow-leaf gentian, Gentiana asclepiadea from the high pastures of Europe, producing clumps of arching stems, studded with tubular flowers. It’s not fussy about soil, preferring it to be rich, moist and semi-shaded. It’s a great addition to the border, making a feature when many other perennials are past their best.