Variety traits

Plant height — black-eyed Susan, cone flower

Rudbeckia hirta L.

An important morphological trait of Rudbeckia hirta, varying from 25 to 120 cm depending on the cultivar and growing conditions. Plant height determines the ornamental use of the plant and its resistance to lodging.

In the reference 9 varieties crop Black-eyed Susan, where this is mentioned in the description.

Typical height values for black-eyed Susan range from 25–30 cm to 100–120 cm. Low-growing (dwarf) forms reach 25–40 cm and are used for container cultivation, whereas tall varieties, reaching 70–120 cm, are used as accents in flower beds.

Plant height directly correlates with the level of nitrogen nutrition and light intensity. An excess of nitrogen above 100 ppm N provokes undesirable stem elongation, reducing aesthetic appeal and the number of flowers. Tall forms are susceptible to lodging from wind and rain, which must be taken into account when choosing a planting site.

The measurement is carried out from the soil level to the top of the inflorescence during the peak flowering phase on healthy specimens. This parameter is a key criterion in breeding and variety testing for determining the suitability of a cultivar for specific landscape tasks.

General information about the subject — on the page Plant height.

Sources8

Varieties of Black-eyed Susan mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.