- Caernavon (s) - Purple mahogany. Sharpe, ca. 1968.
- Cambridge (s) - Pale blue. Colledge, 1964.
- Camilla (s) - Lavender. 1992.
- Can-Can (s) - Rose pink.
- Candy(1) (s) - Salmon pink, cream ground. Cullen, ca. 1952.
- Candy(2) (s) - Maroon stripe. Beane, 1991.
- Candy Frills (s) - Lavender. 1977.
- Capri (s) - Pale blue. 1936.
- Caprice (s) - Blue. 1975.
- Capricorn (s) - Cerise. Place, 1999.
- Captain Lewin (s) - Glossy maroon. Harrod.
- Captain of the Blues (g) - Mid blue. Echford, 1891.
- Captain Scott (s) - White. 1981.
- Cara Hepworth (s) - Orange-red. Walker, 2001.
- Cara Stevenson (s) - Pale blue. Kerton 2012.
- Carlotta (s) - Magenta. Carter, 1937.
- Carmen (e) - A carmine rose EMG variety.
- Carnival Queen (s) - Magenta. Grayson, 2004.
- Carol (e,m) - A pink Cuthbertson Florabunda. Cuthbertson.
- Cascade (e) - A white Spencer Praecox.
- Castle of Mey (s) - Rich cream. 2001.
- Castlewellan (s) - Salmon pink, cream ground. Harrod, 2005.
- Catherine(1) (e,m) - A cerise Cuthbertson Florabunda. Cuthbertson.
- Catherine(2) (s) - Orange-red. Harriss, 1985.
- Cathy (g) - Deep cream. 2005.
- Cathy Wright (s) - White. 2000.
- CCC (g) - White. Grayson, 1998.
- Celebration (g) - A series of frilly grandifloras. Brackley, 1993.
- Celia (s) - Magenta. 2006.
- Challenger (s) - Mauve.
- Champagne Bubbles (s) - Salmon pink. 1986.
- Chance (s) - Red/magenta bicolour. Parsons, 2006.
- Charisma (s) - Carmine. 1993.
- Charles Unwin (s) - Salmon pink, cream ground. Colledge, 1985.
- Charley Paige (s) - Pink stripe, white ground. Manston, 2008.
- Charlie (s) - Deep violet-maroon. 2003
- Charlie's Angel (s) - Light blue. Hanmer, 1990.
- Charlotte Emma (s) - Pink. Kerton, 2009.
- Charlotte Ryley (g) - Violet. Grayson, 1997.
- Chatsworth (s) - Pale blue. Albutt, 1998.
- Chelsea Centenary - Synonym of Crystal.
- Cherry Ice (g) - Scarlet. 1998.
- Cheshire Dark Blue (g) - Purple- blue. Synge, pre 1964.
- Chloe (e,m) - A deep purple EMG.
- Chris Harrod (s) - Light blue. Harrod, 2008.
- Cirrus - Synonym of Queen of Hearts
- Claire Elizabeth (s) - Picotee, white ground. Hunt, 1988.
- Clementine Kiss (s) - Orange, darkening as it matures. Matthewman, 2011.
- Cocktail (s) - Maroon / violet bicolour. Hammett.
- Colin Unwin (s) - Cerise. Colledge, 1987.
- Coline (e,m) - Cerise or scarlet Cuthbertson Florabunda. Cuthbertson.
- Colleen Mary (s) - Salmon pink, cream ground. Tierney, 2008.
- Columbus (m) - Pale blue multiflora. Unwin, 1993.
- Comet(1) (s) - Carmine. Dobbie, 1964.
- Comet(2) (s) - Light pink stripe. Unwin, 1998.
- Concorde (s) - Bright carmine rose. 1981.
- Connie (e,m) - Deep rose pink Cuthbertson Florabunda. Cuthbertson.
- Constance Hilton (s) - White. Hinton, 1914.
- Cooltonagh Pink - Pink. Harrod.
- Coquette (e,m) - A picotee EMG.
- Coraleena (s) - Scarlet cerise. Harrod, 2009.
- Corinne (s) - Carmine. Bolton, 1976.
- Countess Cadogan (g) - Rich violet-blue. Eckford, 1899.
- Countess Spencer (s) - Pink.
- Cream Beauty (s) - Cream. B.R.Jones, 1975.
- Cream Cracker (s) - Cream. Wells, 2005.
- Cream Delight (s) - Cream. 1950.
- Cream Elegance (s) - Cream.
- Cream Ripple (s) - Lilac stripe on cream. Kerton, 1995-98.
- Cream Southbourne (s) - Cream. Colledge, 1982.
- Cream Triumph (s) - Cream. Woodcock, ca. 1964.
- Cupani - Intense maroon/violet bicolour. 1699.
- Crimson Ripple (s) - Red stripe, 2002.
- Crown Prince of Prussia (g) - Pink/pale blue bicolour. 1868.
- Crystal (s) - Pale blue. Hammett, 2010.
- Curbar Edge (s) - Rose pink, cream ground.
- Cuthbertson Florabunda (e,m) - A spring flowering series. Cuthbertson, 1940s.
- Cyril Fletcher (s) - Rose pink. 1984.
- Cyril Plater (s) - Rosy mauve. Kerton, 2011.