| Cultivar Name | Plant Size | Leaf Color | Variegation | Var Color | Origin | Flower Color | Season | Source | Registered |
| 'Canadian Foreign Affairs' | Giant | Light-Green | | | Unknown | Pale-Lavender | July to August | Knechtel, Ken & Ruh, Peter | .2002 |
| 'Canby' | Large | Med-Green | Marginal | Yellow | Unknown | Med-Lavender | July to August | Tompkins, Chet & Ruh, Peter | .2003 |
| 'Candy Hearts' | Medium | Blue/Green | | | Hybrid | Pale-Lavender | July | Fisher, Eunice V. & Ruh, Peter | .1998 |
| 'Cantabi' | Small | Med-Green | | | Unknown | Med-Lavender | June to July | Hirao, Shuichi & Ruh, Peter | .2001 |
| 'Captain Teach' | Medium | Dark-Green | | | Hybrid | Med-Lavender | July to August | Sugita, Hajime & Ruh, Peter & Ruh, Jean | .2001 |
| 'Cardwell Yellow' | Large | Yellow | | | Unknown | Near-White | June to July | Krossa, Gus & Ruh, Peter | .1981 |
| 'Carl' | Small | Blue/Green | | | Unknown | Pale-Lavender | June to July | Calderara, Carl & Ruh, Peter | .1991 |
| 'Carrie Ann' | Small | Blue/Green | Marginal | White | Unknown | Pure-White | August | Stone, David & Ruh, Peter | .1988 |
| 'Cartwheels' | Medium | Blue/Green | Marginal | Yellow | Sport | Near-White | July | Summers, Alex & Ruh, Peter | .2002 |
| 'Chesterland Gold' | Medium | Yellow | | | TC Sport | Pale-Lavender | July to August | Zilis, Mark & Ruh, Peter | .1997 |
| 'Chinese Sunrise' | Medium | Med-Green | Marginal | Greenish White | Sport | Pale-Lavender | August to September | Schaeffer, Robert & Ruh, Peter | .1992 |
| 'Chodai Ginba' | Medium | Dark-Green | | | Unknown | Pale-Lavender | July | Kajigawa & Ruh, Peter | .2003 .2018 |
| 'Chuck's Sweetheart' | Small | Med-Green | | | Unknown | Med-Lavender | Unknown | Purtymun, Charles & Ruh, Peter & Ruh, Jean | .2009 |
| 'Color Riot' | Small | Med-Green | Medial | White | Hybrid | Pale-Lavender | June to July | Tompkins, Chet & Tompkins, Cynthia & Ruh, Peter | .2010 |
| 'Condor' | Small | Med-Green | | | Hybrid | Light-Purple | August to September to October | Sugita, Hajime & Ruh, Peter | .2002 |
| 'Craig Harlequin Bells' | Medium | Dark-Green | | | Unknown | Light-Purple | June to July | Craig, Jack & Ruh, Peter | .1998 .1999 |
| 'Craig's Temptation' | Small | Dark-Green | | | Hybrid | Light-Purple | July | Schenk, George & Ruh, Peter | .2002 |
| 'Cross Stitch' | Large | Med-Green | | | Hybrid | Light-Purple | July to August | Zumbar, Wm & Ruh, Peter | .1992 |
| 'Crown Prince' | Small | Yellow | Marginal | Green | Unknown | Light-Purple | August | Ross, Henry & Ruh, Peter | .1987 |
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