| Cultivar Name | Leaf Color | Variegation | Var Color | Origin | Flower Color | Season | Source | Registered |
| 'Cabin Boy' | Light-Green | - | - | Hybrid | Light-Purple | July into August | Kwick, Charles | .2017 |
| 'Cadillac' | Yellow | Marginal | Blue-Green | Unknown | Near-White | July | Avent, Tony | .1998 |
| 'Carol Marie' | Light-Green | - | - | Hybrid | - | June into July | Kwick, Charles | .2016 |
| 'Child of the Queen' | Blue/Green | Medial | Yellow | Nat-Sport | - | - | van den Top, Jan | --NR-- |
| 'Christmas Tree Gala' | Dark-Green | Streaked | Yellow | Nat-Sport | Med-Lavender | July | Powell, Loleta | .2000 |
| 'Corkscrew' | Med-Green | - | - | Hybrid | Light-Purple | August to October | Solberg, Robert | .2003 |
| 'Cosmopolitain' | Med-Green | Marginal | White | Hybrid | Near-White | - | Bastille, Jocelyne | --NR-- |
| 'Cotton Candy' | Med-Green | Streaked | Speckles | Nat-Sport | Med-Lavender | July into August | Zilis, Mark | .2009 |
| 'Creek' | Blue/Green | - | - | Hybrid | Pure-White | June | Wade, Van | .2007 |
| 'Crossing the Rubicon' | Yellow | - | - | TC Sport | - | June into July | Zilis, Mark | .2009 |
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