“You’re a botanist, so this will be easy. Can you name 10 truly blue flowers?” I was asked this question in a job interview straight out of university and my awkward inability to instantly rattle off a list, without lots of head scratching and pained facial expressions, has fascinated me since. Until that moment, it had not occurred to me that only a tiny proportion of plants produce blue flowers, making this an insidiously tough way to test someone’s plant knowledge. But good things in life are rarely easy to come by. As you browse the seed catalogue this autumn, here are some blue botanical curiosities to bear in mind.
Blue-coloured flowers are probably not rare due to some kind of evolutionary pressure that puts pollinators off this hue, but because the nuts and bolts of how to create this pigment are really tricky. The plants that do achieve it often use the compounds that normally give flowers and fruit red, purple and black shades, and modify them using clever chemistry, such as increasing the pH in their cells, to make it appear blue – sort of biological litmus test.
A blue rose has been the holy grail for plant breeders for centuries. But it’s a creation we now know to be scientifically impossible without genetic modification (or injecting synthetic dye). It’s this rarity, combined with how amazingly well they mix with white, greys and silvers to stand out in low light, that makes all blue flowers so beguiling.
Perhaps the most famous blue flowers are the Himalayan blue poppies, Meconopsis sp. Their translucent petals in haunting sky blue demand consistently cool, wet conditions that mimic their native Himalayan habitat to fare well. If you are lucky enough to live in mild areas of Scotland or the north of England, rejoice in the fact that you’re in one of the few climates on the planet where these will be happy. Fortunately, there are a tiny handful of much easier options available – if you know where to look.
Flax, or Linum narbonense, has delicate, silk-like flowers in the softest powder blue. It’s really easy to grow as an annual “meadow”, directly sown into any patch of well-drained ground in full sun. You can even sow them from a packet of seed bought in the health food aisle and maybe save yourself a few quid. Similarly, the star-shaped, light blue flowers of borage (Borago officinalis) will come back year after year from self-sown seed. A well-drained, sunny spot is also perfect for love-in-a-mist (Nigella damascena), which are available in a mind-boggling diversity of ruffled forms, with a filigree veil of green sepals encasing their magical blue blooms. Sow seeds for all three and get a triple dose of otherworldly marine hues next spring – something to dream about in the dreary grey of winter.
Follow James on Twitter @Botanygeek