| Cultivar Name | Plant Size | Origin | Flower Color | Season | Source | Registered |
| 'She Don't Know She's Beautiful' | Large | Unknown | - | June into July | Kwick, Charles | .2016 |
| 'Taiwan' | Medium | Hybrid | - | - | Syre-Herz, Ursula | --NR-- |
| 'Talcott Mountain' | Large | Unknown | - | - | Parks, David | --NR-- |
| 'Tangerine' | Medium | Hybrid | Pale-Lavender | July | Elslager, Ed | .1998 |
| 'Tardiflora Golden' | - | Sport | - | - | Schaeffer, Robert | --NR-- |
| 'Tardiflora Honey Glaze' | Small | Sport | Med-Lavender | August to October | Unknown | --NR-- |
| 'Tawny' | Small | Unknown | - | - | Lydell, Ransom | --NR-- |
| 'Tear Drop Of The Sun' | Medium | Unknown | - | - | Unknown | --NR-- |
| 'Temperature Rising' | - | Hybrid | - | - | Donsky, George | --NR-- |
| 'Templar Gold' | Medium | Unknown | Med-Lavender | July | Deckert, Emile & Deckert, Jane | .2004 |
| 'Ten Karat Gold' | Medium | Hybrid | - | - | Zilis, Mark & Ruh, Peter & Ruh, Jean | .2008 |
| 'Tequila Sunrise' | Medium | Hybrid | - | - | Johnson, Greg | .2004 |
| 'The Gambler' | Large | Sport | Pale-Lavender | July into August | Zilis, Mark & Schwarz, Karen | .2014 |
| 'The Minnesota Mafia' | Large | Hybrid | - | June into July | Naylor Creek Nursery & Larsen, Kim | .2009 |
| 'The Shining' | Large | Sport | Pale-Lavender | August | Hansen, Hans | --NR-- |
| 'The Sun' | Large | Unknown | - | - | Goodwin, Randy | --NR-- |
| 'The Sun King' | Large | Unknown | Near-White | July | O'Harra, Russ | .1999 |
| 'Thelma M. Pierson' | Large | Sport | Light-Purple | June into July | Pierson, Robert | .1988 |
| 'Thomas Jefferson' | Large | Unknown | Near-White | June into July | Sugita, Hajime & Ruh, Peter | .2001 |
| 'Tickle Me Pink' | Small | Hybrid | Light-Purple | July into August | Hack, J. & Stegeman, Bev & Stegeman, Dave | .2006 |
| 'Tijuana Brass' | Medium | Hybrid | Pale-Lavender | July | Vaughn, Kevin | .1988 |
| 'Tiki Torch' | Large | Unknown | Pale-Lavender | - | Rawson, Don | --NR-- |
| 'Timber Blaze' | Medium | Unknown | Med-Lavender | - | Hackbarth, Robert | .2015 |
| 'Timothy J. Wright' | Medium | Unknown | Med-Lavender | - | Chamberlain, Steve | .2015 |
| 'Tiny Dancer' | Small | Unknown | Pale-Lavender | July | Benedict, Dr Ralph (Herb) | --NR-- |
| 'Tochi Ogon Iwa' | - | Unknown | - | - | Unknown | --NR-- |
| 'Tokudama Ogon Hime' | Small | Sport | Near-White | June into July | Unknown | --NR-- |
| 'Tom Boy' | Medium | Unknown | - | June into July | Benedict, Dr Ralph (Herb) & Benedict, Dorothy & Kuenster, Rod | .2010 |
| 'Tom Terrific' | Large | Hybrid | Pale-Lavender | July into August | Solberg, Robert | .2019 |
| 'Too Darn Hot' | Medium | Hybrid | Near-White | July | Ward, Dr Dick & Ward, Jane | .2009 |
| 'Top Brass' | Giant | Hybrid | Med-Lavender | June into July | Gilligan, Madelon | .2013 |
| 'Top Dog' | Medium | Hybrid | - | June into July | Ward, Dr Dick & Ward, Jane | .2009 |
| 'Top of the Mornin' | Medium | Hybrid | Med-Lavender | August to September | Dean, Don | .2017 |
| 'Tortilla Chip' | Medium | TC Sport | Pale-Lavender | July into August | Solberg, Robert | .2002 |
| 'Tosayama' | Small | Unknown | - | - | Sugita, Hajime | --NR-- |
| 'Toutatis' | Small | Unknown | - | June into July | Deckert, Emile & Deckert, Jane | .2004 |
| 'Treasure' | Large | Hybrid | Pale-Lavender | June | Harshbarger, Gretchen | .1981 |
| 'Tremont Afterglow' | Medium | Hybrid | Pale-Lavender | July into August | Livingston, Ron | .2013 |
| 'Tremont Back to Yellow' | Large | Unknown | - | - | Livingston, Ron | --NR-- |
| 'Tremont Red Rover' | Small | Unknown | - | - | Livingston, Ron | --NR-- |
| 'Tremont Upright Gold' | Large | Unknown | Med-Lavender | - | Livingston, Ron | --NR-- |
| 'Trisha's Sunny Paradise' | Small | Sport | Deep-Purple | July | McHugh, Ed | .2012 |
| 'Tupelo Honey' | Large | Unknown | - | June into July | Wasitis, Chick | .2011 |
| 'Tweety Bird' | Small | Unknown | - | June into July | Schwarz, Jim | .1997 |
| 'Tweetypie' | Small | Unknown | - | - | Unknown | --NR-- |
| 'Twenty-four Carat Gold' | Large | Sport | Pale-Lavender | - | Anderson, Jim | --NR-- |
|