The late-season perennial daisy Rudbeckia is emerging from a long period of neglect as plantsmen and designers rediscover its robust but graceful charms. The main reason for this revival is its role as a stalwart of the new prairie planting schemes, pioneered over the past decade by leading designers such as Piet Oudolf.
The tall butter-yellow flowers of Rudbeckia complement ornamental grasses well and they are tough enough to hold their own in these low-maintenance, high-density designs. Their selection for such plant combinations is no accident: the wild species inhabit the prairies of the American Midwest, where they cope with scorching winds and baking drought with little shelter. They have evolved to become very resilient, needing little extra care to perform at their best.
But their long spell in the horticultural wilderness has meant that the range available is only just beginning to expand. There is little breeding work being done on the perennial group: one reason is the over-arching popularity of just one cultivar, R. fulgida var. sullivantii 'Goldsturm' Award of Garden Merit (AGM), which has outperformed other types and remains the best-known Rudbeckia.
Many other fine cultivars are now finding their way into the UK market: the tall ones in particular, such as R. laciniata 'Herbstsonne' AGM and the fashionable R. fulgida var. deamii AGM attract attention as elegant, imposing, late-summer performers.
The exception to the slow rate of introductions is the ever-expanding group of short-lived Rudbeckia, mostly bred from R. hirta. They are generally treated as annuals and sold as seed or plug plants, so may have limited appeal as nursery stock, but it is here that the widest range of colours can be found. Thompson & Morgan has just released the first red variety, R. x hirta 'Cherry Brandy', and there are also bicolours and double forms.
Customers who have concentrated on early- summer-use Rudbeckia to plug the colour gap in August and this is the time of year when growers report the plants flying off the shelves as their vivid yellow daisies splash colour into front-of-house displays.
Their saleability is helped by their easy-going nature: they suffer few pests and diseases, tolerate drought and are largely well behaved and non-invasive. They are sometimes recommended for part shade, but tend to get leggy in low light levels and are much better in full sun.
Taller varieties are best in poorer soils, where they grow sturdy and do not need staking. They are undemanding, and as a wider range becomes available and prairie planting shows no sign of waning, interest in this handsome group of plants can only increase.
WHAT THE SPECIALISTS SAY
Anthony Brooks, National Collection Holder, Shropshire "I focus mainly on perennial types - the seed strains are so changeable.
"There hasn't been much breeding work in perennial types: Echinacea has really taken off, but not Rudbeckia. But the promotion of prairie-style planting has made it more popular.
"I've raised a couple of R. laciniata types - R. laciniata 'Starcadia Razzle Dazzle' is popular, useful and clump-forming.
"There's not much you can do with yellow daisies. R. fulgida var. sullivanti 'Goldsturm' Award of Garden Merit (AGM), for one, is difficult to better as it is long-flowering and reliable.
"It's important to plant them in the right place. The taller plants in particular need moisture to sustain them. They prefer full sun and tend to become leggier and weaker-stemmed in the shade."
Jason Bloom, nursery manager, Blooms of Bressingham, Norfolk "My grandfather bred R. lacinata 'Goldquelle' AGM; we grow quite a few types. One of the top 10 perennials for my father and my grandfather is R. fulgida var. sullivanti 'Goldsturm' AGM. R. subtomentosa is also a good plant - it's quite tall but gives a phenomenal show.
"It's a relatively limited group: you won't get much difference in colours except with R. hirta varieties, which are biennial. They're not reliable performers so they are treated differently.
"They're tough and trouble-free. They grow on clay and don't like dried-out soil and winter wet."
Nigel Judd, professional grower manager, Thompson & Morgan, Suffolk "We're doing quite a bit of breeding work and this year we introduced the first red variety, R. x hirta 'Cherry Brandy'.
"We're getting over a 60 per cent survival rate with the milder winters, but generally they're not great for growers to over-winter. But the compacts make a good late-summer display in pots and the bigger ones such as R. hirta 'Chim Chiminee' are great as mass bedding and go right into autumn.
"They're drought-tolerant and prefer sunny conditions, but also look good after a wet summer."
Martin Hughes-Jones, owner, Sampford Shrubs, Devon "We stock R. fulgida var. sullivanti 'Goldsturm' AGM, R. fulgida and a couple of selections of R. subtomentosa.
"R. fulgida var. deamii AGM has real poise and the longest flowering period. Also R. laciniata 'Herbstsonne' AGM is tall and good in the right spot.
"Prairie planting isn't the only way to grow them - we've just come back from the Loire Valley where there are some stunning amenity plantings using Rudbeckia with Cleome, Salvia and Pennisetum."
SPECIES AND CULTIVARS
R. fulgida var. deamii Award of Garden Merit (AGM) is a newly fashionable cultivar championed by designers for its airy, open habit, its profusion of golden-yellow flowers and its exceptionally long flowering period.
R. fulgida var. speciosa AGM is similar to R. fulgida var. deamii AGM but makes a slightly shorter, more compact plant. It is less floriferous and has a shorter flowering season.
R. fulgida var. sullivantii 'Goldsturm' AGM is the best-selling perennial Rudbeckia. Its deep-yellow flowers are borne very reliably and in profusion.
R. hirta 'Indian Summer' AGM is usually raised from seed. It has large flowers, up to 20cm across, and is variable with semi-double and single blooms. Bright yellow petals fade to darker ochre at the centre, with a dark brown eye.
R. hirta 'Prairie Sun' has unusual colouring with orange petals fading to pale yellow and a green central cone. Growing to 80cm, it is one of the taller short-lived varieties.
R. hirta F1 'Tiger Eye' is new in production this year. The first F1 hybrid, it has strong, regular, long-lasting golden-yellow flowers on 40-60cm stems.
R. hirta 'Toto' AGM is one of the smallest cultivars, at just 30cm tall. It is usually grown from seed, with a compact, bushy habit, and is ideal for containers.
R. x hirta 'Cherry Brandy' is a new introduction and the first red variety.
R. laciniata 'Goldquelle' AGM has double, pom-pom-like golden-yellow flowers and grows to 1m. It is a reliable performer at the back of the border, where it rarely needs staking.
R. laciniata 'Herbstsonne' AGM is a spectacular plant, growing to 2.5m. It has lemon-yellow flowers with reflexed petals on slender stems and a particularly dark leaf colour.
R. laciniata 'Starcadia Razzle Dazzle' is a new introduction that forms well-behaved clumps of tall, yellow daisies on sturdy stems to 2m, with a long flowering period.
R. maxima makes an elegant plant with prominent, elongated, black central cones and large, drooping petals. The whippy stems make this a "see-through" plant for mid-border positions, where its unusual paddle-shaped blue-green leaves can be appreciated.
R. occidentalis 'Black Beauty' has odd-looking flowers, with a very prominent black central cone dotted with tiny yellow petals. It reaches 90cm and flowers from July to October.
R. occidentalis 'Green Wizard' is similar to 'Black Beauty' but has even smaller ray florets, forming a single ring around the cone, and bright green sepals.
R. subtomentosa has silvery, downy leaves on tall stems up to 2m high and is spectacular when smothered in clear yellow, black-centred flowers from July to October.
R. subtomentosa 'Henry Eilers' is a selection with a similar habit to the species, but with unusual quilled petals, giving flowers a delicate, star-like appearance.
R. 'Takao' is short-lived and grows up to 75cm. It is a robust and vigorous plant, with small, yellow flowers bearing neat petals clustered around a chocolate-brown cone.
R. triloba AGM is one of the smallest species, growing to just 60cm. It is short-lived and has small, clear yellow flowers with a dark central cone. Its wiry stems give it an airy habit.