- Lady Diana (s) - Lavender. 1985.
- Lady Fairbairn (s) - A pale mauve sweet pea, named after a former president of the NSPS.
- Lady Grisel Hamilton (g) - Clear lavender with hooded standard. Eckford, 1898.
- Lady Penny (s) - Lavender. 1995.
- Lady Seymour (s) - Dark Blue.
- Lady Susan (s) - Orange-pink. 1997.
- Lady Turral (g) - Magenta standard with lilac wings. Turral, 1962.
- Lady's Bonnet (g) - Pale blue modern grandiflora with a distorted standard. Grayson.
- Lake Windermere (s) - Attractive two tone blue sweet pea. Very small seed, but good germination. 2003.
- Larkspur (s) - A very old pale blue variety.
- Laura (s) - Crimson.
- Laura Webster (s) - Large pink flowered exhibition sweet pea. Hammett.
- Lauren Landy (s) - Warm rose pink on white. Harrod.
- Lavender Glory (e) - A lavender Spencer Praecox sweet pea.
- Leading Light (s) - Reverse bicolour. 2006.
- Leamington (s) - An old lavender sweet pea, now degenerate.
- Ledi (s) - Magenta pink. Adie, 2008.
- Leominster Boy (s) - Salmon orange. Beane, 2009.
- Leonard Montague (s) - Salmon cerise with white eye. Harrod.
- Lianne Marie (s) - Magenta. 1997.
- Lilac Ripple (s) - Excellent lavender stripe sweet pea. Also known as 'Pulsar'. Thomas, 1989.
- Lilac Romance (s) - A large frilly lilac sweet pea. Wells, 2009.
- Lilac Silk (s) - Pale pink.
- Lilac Time - Lavender.
- Lillie Langtry (s) - Cream.
- Lily Price (s) - Magenta. Walker, 1998.
- Limelight (s) - Pale green when grown under light shade or under glass, ivory in full sun. Rowland 2002.
- Linda C (s) - Mid blue. Chisholm, 2001.
- Linda Carole (s) - Red stripe. 2004.
- Linda Mary (s) - Pink stripe on cream. Parsons, 2007
- Lipstick - Vivid carmine red exhibition sweet pea. Hammett, 2008
- Lisa Marie (s) - Chocolate stripe. 2004.
- Lively Lassie (s) - Lavender flush. 2002.
- Liz Bolton (s) - Rose pink.
- Lizbeth (s) - A large flowered orange-red sweet pea. Tremewan, 1993.
- Lois (e) - A deep rose pink Cuthbertson Florabunda variety. Cuthbertson.
- Lord Nelson (g) - Deep purple-blue. House, 1907.
- Louise (s) - Salmon pink, cream ground.
- Lovejoy (s) - Maroon.
- Lovely Lady (s) - Mid blue. 2002.
- Lucinda Jane (s) - Cerise pink. Grayson, 1993.
- Lucy (s) - Salmon pink on cream. 1996.
- Lucy Jane (g) - A purple picotee on cream old fashioned sweet pea. Grayson, 2004.
- Lunar Sea (e) - An early flowered cream sweet pea. Hammett, 2009.
- Lynn Davey (s) - A top quality modern lavender sweet pea. James, 1998.
- Lynn Fiona (s) - Pale pink on cream ground. Robertson.