Colour is more joyous during the bleak, chilly months than it is during summer. At this time of year, one of the best plants for providing it is the coneflower (Rudbeckia). Amid the autumn mists, under grey skies, its bright-yellow daisy flowers shine a glorious shade of gold.
There are 24 species, all of them native to North America: predominantly found in the United States. They hail from a range of habitats, including prairies, which is the reason for their surge in popularity. As prairie-style planting has become fashionable in recent years, so the long-flowering, informal beauty of the rudbeckia is employed by garden designers looking to create naturalistic, meadow-inspired borders.
In the past, Native Americans used the rudbeckias of the prairies – including Rudbeckia hirta (black-eyed Susan), R. laciniata (cut-leaved coneflower), and R. triloba (brown-eyed Susan) – as medicine. The roots and dried leaves were made into tea or poultice and employed to treat a variety of illnesses, including cold, flu, infection, inflammation, earache, and snake bite. Modern studies indicate that the plant does indeed strengthen the immune system and has anti-inflammatory, antioxidant, and antimicrobial properties.
The plant was named by the Swedish botanist Carl Linnaeus, in honour of his mentor, Olof Rudbeck the Younger, a fellow botanist at Uppsala University, and his father, Olof Rudbeck the Elder, a naturalist and doctor. ‘I have chosen a noble plant in order to recall your merits and the services you have rendered,’ Linnaeus wrote in his dedication, ‘a tall one to give an idea of your stature, and I wanted it to be one which branched and which flowered and fruited freely, to show that you cultivated not only the sciences but also the humanities. Its rayed flowers will bear witness that you shone among savants like the sun among the stars.’
When rudbeckia flowers in the depths of autumn, glowing bold shades of yellow, while much of the garden is brown and bare, it does shine like the sun. On top of this, it lures butterflies and other pollinators and provides birds (such as goldfinches) with seeds. Even if you only have room for one plant, it will brighten the season with blazing colour and wildlife.
Which rudbeckias to grow
Of the longer-lived perennial forms, the most impactful is Rudbeckia laciniata ‘Herbstsonne’. From August to October, it is a glorious mass of colour at the back of the border, producing flowers with green hearts and reflexed lemon-yellow petals on stems that soar to 2 metres or more. R. laciniata ‘Starcadia Razzle Dazzle’ is similar, but slightly shorter.
Another covetable tall form is the sweet coneflower (R. subtomentosa) ‘Loofahsa Wheaten Gold’, which has a classic rudbeckia look, producing large golden daisies with dark centres on 1.5-metre stems. R. maxima (the great coneflower) is perfect for a contemporary garden, having golden flowers with protruding brown cones, atop bare 1.5-metre stems, above large glaucous leaves.
In the middle of the border, R. triloba is a favourite of garden designers for creating a naturalistic look. The species has compact yellow blooms with brown centres and ‘Prairie Glow’ is a wonderful copper-flowered version. For the front of the border or pots, low-growing perennial choices include forms of the orange coneflower (R. fulgida), such as ‘Goldsturm’, R. f. var. deamii, and ‘Early Bird Gold’, which bear generous golden daisies with chocolate centres.
All of the perennials mentioned above have single flowers that provide food for pollinators. But there are double rudbeckias with shaggy yellow lion’s-head blooms, which offer a bit of variety if you want to grow several types. They include the 2-metre-tall R. laciniata ‘Hortensia’ and ‘Goldquelle’, which is shorter at 90 centimetres.
Some rudbeckias are not reliably hardy, so they are grown as annuals (or short-lived perennials in milder regions). The rich autumnal shades of R. hirta light up the season, and they could be grown in the productive garden as cut flowers. Some of the best include ‘Cherry Brandy’ (velvet red), ‘Cappuccino’ (copper and maroon), ‘Goldilocks’ (double amber), and ‘Sahara’ (a mix of dusky peach and terracotta shades), all of which grow to around 60 centimetres. Another annual form to try is the clasping coneflower (R. amplexicaulis), which is useful for filling gaps at the front or in the middle of the border late in the season: it has bold-yellow flowers with tall brown hearts that resemble Mexican hats.
How to plant rudbeckias
Coneflowers bloom best in full sun, but will tolerate semi-shade. Ensure the soil is moderately fertile, retentive and well-drained by forking in organic matter (such as peat-free compost) before planting.
Rudbeckias being grown from seed as annuals can be sown indoors (in a warm greenhouse or on a sunny windowsill) between February and April – sow thinly and shallowly (or don’t cover at all). Pot up seedlings once they are large enough to handle. Alternatively, sow direct in April or May. Some perennial rudbeckias are also relatively easy to grow from seed, including R. maxima and R. triloba. The latter will often sow itself around the garden.
How to grow rudbeckias
Coneflowers dislike drought. In regions that experience hot, dry summers, mulch annually in spring (for instance, with organic peat-free compost) to ensure the plants can retain as much moisture as possible, and water daily during heatwaves.
Planting in full sun, with shelter from strong winds, will lure lots of butterflies. Leave the attractive seedheads on the plants for winter interest and to provide a habitat for insects and food for birds.
Coneflowers can be lifted and divided every 4-5 years in spring to maintain flower power or to make new plants. The more rampant forms (especially R. laciniata) are best grown in larger gardens; otherwise, they need dividing regularly.
Rudbeckia pests and diseases
In wet years, slugs can strip young coneflower plants entirely, leaving you with nothing but slime-coated stalks. Prevent such horror by laying down effective arsenal, such as Nemaslug or crushed shells. In dry years, the plants can be plagued by powdery mildew if they are not planted in a site that has good air flow or in soil that is not moisture retentive.
