Rudbeckia hirta 'Denver Daisy' has large, golden daisies with chocolate brown centres and marks at the base of each petal. This lovely garden flower performs well, is exceptionally heat tolerant and blooms for a long time in summer.
Rudbeckia hirta, commonly known as the Black-eyed Susan, is a short-lived perennial that is native to much of North America. It is wonderfully easy to grow and blooms for an extended period of time.
A warm season bloomer, the plants form a clump of foliage from which rises thick, leafy stems topped with colourful daisy shaped flowers throughout the summer. Deadhead regularly to encourage continued bloom.
Growing to around 75cm (30in) tall, flower arrangers will find that the attractive blooms of this variety are produced on strong stems and last for a long time in water.
With prominent central cones, they attract pollinators such as bees and butterflies. If the seed heads are left to dry, they will attract seed eating birds. Like many black-eyed Susans, they will self-sow gently. Rudbeckia hirta grows best in full sun and well-drained, average soil, allow the soil to dry between watering. This popular ornamental is at home in wildlife gardens, cutting gardens and mixed borders.
Sowing: Sow in late winter to late spring.
Rudbeckia hirta is a short-lived perennial or biennial and is often grown as a half-hardy annual. The seeds are best sown indoors in warmth before transplanting outdoors.
Seeds can be sown directly where they are to flower, two weeks before the last expected frosts in your area (usually around May), but to give them a head start, sow indoors from mid February to June, about six to eight weeks before planting outdoors.
The seeds need light to germinate, so just press them into the soil surface or use a little vermiculite - don't bury them.
Sowing Indoors: Late February to early April
Seeds are best sown indoors in pots or trays containing good seed compost. Cover the seed lightly with vermiculite or sieved compost and place in a propagator or warm place maintaining an optimum temperature of 18 to 20°C (65 to 70°F) Keep the compost moist but not wet at all times. Germination mostly occurs between 10 to15 days but will take longer if temperatures are lower.
Thin to 7.5cm (3in) pots when seedlings have developed two proper leaves and are large enough to handle. Remember to handle the seedling by the leaves only, supporting the weight of the seedling under the roots as you transplant.
Grow on and harden off by gradually acclimating to outdoor conditions for 10 to 15 days before planting out into their permanent positions when temperatures start to rise.
Plants transplant well and should be spaced 30 to 45cm (12 to 15in) apart
Sowing Direct: Late April to early June
Sow thinly, 3mm (1/8in) deep in drills 30cm (12in) apart in well-cultivated soil which has been raked to a fine tilth. The plants prefer a position in full sun, with organically rich, evenly moist but well-drained soil.
Water the ground regularly, especially in dry periods. When large enough to handle, thin out seedlings so that they are finally 30 to 45cm (12 to 15in) apart . They require long days and full sun for best flowering.
The trick with Rudbeckia is to make sure it goes in soil which does not bake dry or the whole plant will collapse. A semi-shady position will help if the soil does tend to dry out in summer, as will a thick mulch, applied after a night of heavy rain.
To extend flowering and prevent self-sowing, deadhead the spent flowers, this also makes for a tidier-looking plant. However, there are advantages if the old flowers are left alone, the cones have ornamental appeal after the petals have dropped, birds enjoy the seeds in the winter; and you will enjoy the benefits of seedlings next spring.
Rudbeckia hirta is a short-lived perennial or biennial and is often grown as a half-hardy annual, sown indoors in warmth before transplanting outdoors. Theses varieties may survive from year to year if left in the garden, especially if wet winter conditions are avoided, but flowering may be reduced in subsequent years. It self-sows easily and cuttings can be taken in late summer and rooted in the cold frame.
Rudbeckia has no serious pests or diseases and is known to be resistant to deer, heat, and drought, it also tolerates salt well.
Cottage/Informal Garden, Flower Arranging, Pots and Containers, Flowers Borders and Beds. Prairie planting. Drought tolerant. Wildlife Gardens.
These excellent herbaceous mostly perennial plants (some annual or biennial) are originally from the USA. They include around 20 species, with four varieties of Rudbeckia hirta:
- Rudbeckia hirta var. angustifolia. Southeastern United States (South Carolina to Texas).
- Rudbeckia hirta var. floridana. Florida, endemic.
- Rudbeckia hirta var. hirta. Northeastern United States (Maine to Alabama).
- Rudbeckia hirta var. pulcherrima. Widespread in most of North America (Newfoundland to British Columbia, south to Alabama and New Mexico; naturalised Washington to California).
The name was given by Carolus Linnaeus in honour of his teacher at Uppsala University in Sweden, Professor Olof Rudbeck the Younger (1660-1740), (aka Olaus Rudbeckius), and his father, Professor Olof Rudbeck the Elder (1630-1702), both of whom were botanists. It is pronounced rud-BEK-ee-a.
The species name hirta comes from the Latin hirsutus meaning ‘covered in hair’ and refers to the trichomes (hairs) occurring on leaves and stems.
Rudbeckia hirta varieties are tender perennials and are most often grown as an annual. There are also other varieties of Rudbeckia which are hardy perennials.
Rudbeckia is one of at least four genera within the flowering plant family Asteraceae whose members are commonly known as coneflowers; the others are Echinacea, Dracopis and Ratibida.
Rudbeckia hirta 'Denver Daisy' was named to commemorate the city of Denver, Colorado’s 150th anniversary in 2008.
- Additional Information
Average Seed Count 30 Seeds Seed Form Natural Family Asteraceae Genus Rudbeckia Species hirta Cultivar Denver Daisy Common Name Black-Eyed Susan. Coneflower Hardiness Half Hardy Annual Hardy Short-lived perennial or biennial that is often grown as a Half Hardy Annual. Flowers Large, golden daisies with chocolate brown centres and marks at the base of each petal. Natural Flower Time June to September Height 75cm (30in) Spread 60cm (24in) Position Full sun for best flowering Soil Well-drained/light, Clay/heavy, Moist Germination 10 to 15 days