Rudbeckia maxima (Giant Coneflower)


Botanical Information

FamilyAsteraceae
GenusRudbeckia
Speciesmaxima
CategoryPerennials
OriginSouth-Central United States of America.

Details

USDA Hardiness Zone4a - 9b
USDA Hardiness Ref.
Canadian Hardiness Zone2a - 8a
Canada Hardiness Ref.
RHS Hardiness ZoneH3 - H7
RHS Hardiness Ref.
Temperature (°C)-32 - (-1)
Temperature (°F)-25 - 30
Height1.5 - 2 m
Spread1 - 1.25 m
GrowthFast
Flowering PeriodJune, July

Description and Growing Information

General DescriptionA perennial cornflower with summer flowers that are a beautiful yellow around a dark brown centre and large, blue-green leaves at the base.
LandscapeWorks well in wildflower meadows, prairies and gardens.
PropagationPropagate through seed.
CultivationGrow in full sun in a moist, well-drained soil. Tolerant of heat, minor drought and a range of soils.
PestsSlugs and snails may cause problems on young plants, and the species is susceptible to powdery mildew.
Notable SpecimensThe Devonian Botanic Gardens, Devon, Alberta, Canada. The A. M. Cuddy Gardens, Strathroy, Ontario, Canada.
HabitatNative to open woodland areas, as well as moist prairies and along transportation lines.
Leaf DescriptionPaddle shaped, bluish-green leaves that are notably large (up to 60 cm in length and 25 cm in width) and appear in a basal clump.
Flower DescriptionA brown cone surrounded by yellow rays, to 7.5 cm in diameter, blooming in the summer. The flower is attractive to butterflies.
Fruit DescriptionSmall seeds which remain on the terminal of flower stalks and are a particular favourite of goldfinches.

Photographs