Cultivars
There are many cultivars, please contact your local nursery for available varieties.

'Dainty Marietta'
This annual has all single yellow flowers.

'Honeycomb'
This annual has large mahogany-red flowers with gold edges.

Generally 
Dwarf cultivars are 150 mm, (6 in) tall and medium-size 
Common cultivars are 200-300 mm (12 in) tall.
Large cultivars grows to 550 mm (18 in) tall