| Cultivar Name | Plant Size | Origin | Flower Color | Season | Source | Registered |
| 'Il Gallo d'Oro' | - | Unknown | - | - | Unknown | --NR-- |
| 'Ogon Akikaze' | - | Hybrid | - | - | Unknown | --NR-- |
| 'Ogon Baran' | Medium | Hybrid | Light-Purple | July | Unknown | --NR-- |
| 'Ogon Dai Tokudama' | Large | Unknown | - | - | Watanabe, Kenji | --NR-- |
| 'Ogon Iwa' | Medium | Unknown | Med-Lavender | August to September | Unknown | --NR-- |
| 'Ogon Kanzashi' | Medium | Hybrid | Deep-Purple | June into July | Unknown | --NR-- |
| 'Ogon Ko Urajiro' | - | Hybrid | - | - | Watanabe, Kenji | --NR-- |
| 'Ogon Koba' | Small | Unknown | Light-Purple | August | Unknown | --NR-- |
| 'Ogon Kuro' | Giant | Sport | Pale-Lavender | July into August | Unknown | --NR-- |
| 'Ogon Oba' | Medium | Sport | Pale-Lavender | July | Unknown | --NR-- |
| 'Ogon Otome' | Small | Unknown | Deep-Purple | July | Unknown | --NR-- |
| 'Ogon Otome Hideko' | Miniature | Unknown | - | - | Unknown | --NR-- |
| 'Ogon Sagae' | Medium | Unknown | Pale-Lavender | July into August | Unknown | --NR-- |
| 'Ogon Setouchi' | Medium | Sport | - | - | Unknown | --NR-- |
| 'Ogon Sudare' | Small | Unknown | Pale-Lavender | July | Lantis, Clarence & Ruh, Peter | .2002 .2018 |
| 'Ogon Tsushima' | Medium | Unknown | Light-Purple | July into August | Unknown & Ruh, Peter | .2002 .2018 |
| 'Ogon Urajiro' | Medium | Unknown | - | - | Unknown | --NR-- |
| 'Ogon Wogon' | - | Unknown | - | - | Epstein, Harold | --NR-- |
| 'Oh! Them Golden Slippers' | Large | Hybrid | Light-Purple | July | Elslager, Ed | .2002 |
| 'O'Harra' | Small | Unknown | Deep-Purple | July | O'Harra, Russ & Walek, Kevin | .2009 |
| 'O'Heartland Gold' | - | Unknown | - | - | O'Harra, Russ | --NR-- |
| 'Ohh! Alpha' | Medium | Unknown | - | - | Schulz, Ed | .2009 |
| 'Ohh! Charlotte!' | Large | Unknown | - | June into July | Schulz, Ed | .2012 |
| 'Ohh! Clare' | Large | Unknown | - | July into August | Schulz, Ed | .2016 |
| 'Ohh! Elvira' | Large | Unknown | - | July into August | Schulz, Ed | .2016 |
| 'Ohh! Jewell' | Large | Unknown | Near-White | June into July | Schulz, Ed | .2017 |
| 'Ohh! Laurel' | - | Unknown | - | - | Schulz, Ed | .2009 |
| 'Ohh! Lovilia' | Large | Unknown | Near-White | June into July | Schulz, Ed | .2015 |
| 'Ohh! Ludell' | Small | Unknown | - | - | Schulz, Ed | .2009 |
| 'Ohh! Valeria' | Large | Unknown | - | - | Schulz, Ed | .2009 |
| 'Ohh! Viola' | Medium | Unknown | Near-White | June into July | Schulz, Ed | .2015 |
| 'Old Yeller' | Large | Hybrid | - | - | Unknown | --NR-- |
| 'Olive Oil' | Medium | Hybrid | Pale-Lavender | - | Dishon, Jim | .1996 |
| 'Olympic Fab Five' | Medium | Unknown | - | July into August | Freeman, Franc | .2012 |
| 'Olympic Gold' | Medium | Unknown | Near-White | July into August | Banyai, Pauline | .1986 |
| 'Olympic Gold Medal' | Medium | Sport | Pale-Lavender | July into August | Fransen, Marco & Naylor Creek Nursery | --NR-- |
| 'Olympic Torch' | Large | Hybrid | - | July into August | Goodwin, Randy | .2009 |
| 'Omlett' | Large | Hybrid | - | - | Kohlein, Fritz | --NR-- |
| 'One and Only' | Large | Hybrid | Pale-Lavender | June into July | Ward, Dr Dick & Ward, Jane | .2015 |
| 'Orange Ice' | - | Unknown | - | - | Hawes, James | --NR-- |
| 'Orange Joy' | Small | Hybrid | Light-Purple | July | Carpenter, Kate | .1979 |
| 'Orange Slices' | Medium | TC Sport | Pale-Lavender | July into August | Zilis, Mark | .2003 |
| 'Orange Star' | Medium | Sport | Pale-Lavender | July into August | Van den Top, Jan | --NR-- |
| 'Oriana' | Medium | Sport | Pale-Lavender | July into August | Smith, Eric | --NR-- |
| 'Osiris Ovation' | Large | Unknown | Pale-Lavender | - | Fafard, Serge | --NR-- |
| 'Ovation' | Medium | Hybrid | Pale-Lavender | July | Fafard, Serge | --NR-- |
| 'Overserved' | Small | Unknown | - | - | Shady Characters Nursery | --NR-- |
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