These dusky cultivars are increasing in popularity, as gardeners – who are as susceptible to fashion as any teenager – experiment with new colour schemes and styles. So how do you get a black flower? It's not really black, of course, but a very deep purple or red. The colour is created by anthocyanins – the pigments that create red, purple and blue colours in flowers and fruit. These are present in every part of the plant, including the stems, leaves and roots. They also act as antioxidants, which is why fruits that are high in anthocyanins, such as blueberries, are labelled as superfoods.