Heavy petal!
Turn up the volume in borders... with rampant rudbeckias
Few plants can beat them for sheer flower power
WHEN Swedish botanist Carl Linnaeus was tasked with coming up with a Latin name for a tribe of summer-flowering daisies in the mid- 18th Century, he decided to use the opportunity to honour his mentor, Olof Rudbeck the Younger. As a result, these plants from the prairies of North America became known as rudbeckias.
It’s clear that Linnaeus, the ‘father of modern taxonomy’, who invented the binomial system by which all plants and animals are named, held both Rudbeck and his plant namesake in high esteem.
In a dedication, Linnaeus gushed: ‘So long as the earth shall survive… the rudbeckia will preserve your glorious name.’
Some will find Linnaeus’s words of praise a little over the top, but rudbeckias in full flight are breathtaking.
Few plants can beat them for sheer flower power, with mature specimens capable of producing hundreds of cheerful flowers from early summer until the first frosts of autumn, depending on variety.
A member of the daisy (asteraceae) family, rudbeckias are closely related to heleniums, dahlias, sunflowers and many other popular garden plants.
There are annual, biennial and perennial types, varying from knee- high forms to 8ft-tall giants, and from bushy plants to more slender specimens.
Their single or double blooms are distinctive. The yellow, orange or red ‘petals’ are arranged around a raised central ‘eye’ that is black, brown or green in colour. This distinguishing feature has provided the plants with their common names of coneflower and, in the case of the darker ones, black-eyed Susan.
I should explain that plants in the daisy f a mi l y have special flowering heads. The ‘petals’ are technically sterile ray flowers (containing a colourful ligule to attract passing pollinators) and the cone is actually a dense cluster of tiny disc flowers.
Annual and biennial rudbeckias can be started from seeds sown in spring or grown from young plants that are sold in early summer. Some garden centres will still stock short-lived ones but, in late summer, perennial varieties are widely available as plants in bud or flower, ready to provide a late blast of colour.
In the wild, rudbeckias thrive in meadows, prairies and woodland edges, from Mexico to Canada.
As for our gardens, they prefer moderately fertile, moist but well-drained soil that doesn’t turn rock-solid in summer or become waterlogged in winter.
They’ll flower their socks off in full sun, although will happily tolerate a little shade.
Towering rudbeckias are best placed at the back of borders, while mediumsized plants of around 3-4ft are great for the middle of beds.
Anything smaller is best placed at the front of displays.
Use t aller ones frugally t o add vertical interest and plant shorter varieties in drifts or small groups for maximum impact.
They make good companions for asters, solidago, heleniums, dahlias, achilleas, sedums and other perennials that tend to flower in late summer and early autumn.
If you fancy creating a prairie style, set them against ornamental grasses, such as Calamagrostis ‘Karl Foerster’ and Anemanthele lessoniana.
Extend flowering by dead-heading regularly during summer and early autumn, allowing flowers to remain on perennial plants towards the end of the season to form sculptural black seed-heads that will act as a source of food for birds. Cut growth to ground level in late winter or earlier, if it starts to look bedraggled.
Over time, rudbeckias will form large clumps that are shy to flower. So every four to five years, rejuvenate congested specimens by dividing in autumn or spring – prise from the ground with a fork and tease the roots apart gently to leave several smaller pieces. Bin any dead bits and replant healthy portions.