It is heartening to look upon the garden and still see flowers flourishing after the blazing heat of high summer – especially in spite of our very necessary water restrictions.
One such flowering fool of particular note is the North American native, rudbeckia or black-eyed Susan.
There are over 20 species in this plant genus ranging in hardiness from Zone 3-10. They are highly valued for their ease of cultivation, prolific flowering, longevity as cut flowers and good resistance to most pests and diseases.
Height ranges from 24 inches to 10 feet, so there is a rudbeckia for every landscaping need. The smallest are wonderful in containers…easily slipped into a current bare spot in the garden. The tallest make a wonderful hedge as well as a fantastic focal plant at the back of the border.
Other rudbeckia species are great in a meadow garden or planted in a mass grouping in a side border.
Their bright, daisy-like single, semi-double or double flowers come in various shades of yellow amongst the different species and cultivars. The centre button of the flower, also depending on the species, ranges in colour from black or darkest brown through rust, purple and even green.
Rudbeckias have a long bloom period that stretches from early summer through to late fall. Sometimes even up to the first frost. As if that were not enough, they are marvellous for attracting butterflies and bees to the garden. Let them go to seed and you will lure a multitude of seed-eating birds in the autumn.
All of the species in the rudbeckia genus are not overly fussy about soil and light conditions. Optimally, they do best in moist rich loamy soil but will also perform quite well in average to poor soil. Full sun is preferred, but partial shade is quite tolerable.
Rudbeckia hirta ‘Prairie Sun’ is one cultivar well worth growing for your garden. With its stunning golden petals tipped in bright yellow and an eye-catching light green centre, the gorgeous five inch (13 cm) flowers show off to perfection. ‘Prairie Sun’ was chosen as one of the All American Selections flower winners in 2003. It was also chosen as a European Fleuroselect Gold Medal winner in 2004. (‘Irish Eyes’ and ‘Green Eyes’ are two other rudbeckias with green centres.) ‘Prairie Sun’ grows three feet (90 cm) high and can reach twenty inches (50 cm) wide. Readily self-seeds.
Rudbeckia fulgida var. sullvantii ‘Goldsturm’ is another desirable variety. It was deservedly named Perennial of the Year in 1999 by the Perennial Plant Association. As one of the most popular perennials for over fifty years, its rich golden-yellow blossoms surrounding a dark brown centre show off well in any garden setting. ‘Goldsturm’ grows upwards of two and a half feet (75 cm) tall and blooms from July straight through into October.
All rudbeckias are easily grown from seed but I must admit it took me five attempts to finally get three ‘Goldsturm’ seedlings to sufficient height for transplanting.
Now…if only I could get even one Rudbeckia lacianata ‘Herbstonne’ seedling to grow!
Also known as ‘Autumn Sun’, this cultivar can reach ten feet (3 m) and I have the perfect spot in mind. Right up against the fence. (‘Goldsturm’ and ‘Herbstonne’ are the only two rudbeckias to seriously try my patience in starting from seed.) Some other rudbeckia species worth mentioning are: Rudbeckia maxima, R. nitida, R. occidentalis, (R. o. ‘Green Wizard’ has no ray petals, but elongated bright green sepals surrounding a large almost black centre) and R. triloba.
At a time of year when the garden is feeling the effects of heat and drought, it is nice to know there are a few plants that can take the abuse and keep on giving.