| Cultivar Name | Plant Size | Leaf Color | Variegation | Var Color | Origin | Flower Color | Season | Source | Registered |
| 'Tagi' | Small | Blue/Green | - | - | Hybrid | Light-Purple | September | Davidson, LeRoy | --NR-- |
| 'Tamaryu Iwa' | Miniature | Dark-Green | - | - | Unknown | - | - | Sakata | --NR-- |
| 'Tambourine' | Medium | Med-Green | Marginal | White | Hybrid | Light-Purple | July into August | Lachman, Wm & Lachman, Eleanor | .1987 |
| 'Tanayama Nishiki' | Medium | Med-Green | Marginal | Yellow | Unknown | - | - | Watanabe, Kenji | --NR-- |
| 'Tatsumaki' | Small | Dark-Green | - | - | Hybrid | - | - | Unknown | --NR-- |
| 'Telly's Treasure' | Medium | Dark-Green | Streaked | Yellow | Unknown | - | July into August | Singer, Mary & Elslager, Ed | .2002 |
| 'Teltow The Stork' | Large | Light-Green | | - | Unknown | Near-White | July into August | Entemann, Manfred | .2019 |
| 'Tentacles' | Medium | Med-Green | - | - | Hybrid | Pale-Lavender | August | Seaver, Charles | .1996 |
| 'Terpsichore' | Medium | Med-Green | - | - | Hybrid | Light-Purple | July | Scheer, Alttara | --NR-- |
| 'Terra Marie' | Small | Med-Green | - | - | Hybrid | Pale-Lavender | July | Wade, Van | .2007 |
| 'Terre Haute' | Small | Med-Green | - | - | Unknown | - | July | Goodwin, Randy | .2009 |
| 'The British Are Coming' | Medium | Blue/Green | - | - | Sport | - | - | Silvers, Bill | --NR-- |
| 'The Perfect Storm' | Medium | Med-Green | Streaked | White | Hybrid | Near-White | August | Wrede, Arthur | .2005 |
| 'The Razor's Edge' | Small | Med-Green | - | - | Hybrid | Pale-Lavender | August to September | Terpening, Kent & The American Hosta Society | .2019 |
| 'The Sleeper' | Medium | Med-Green | - | - | Hybrid | Med-Lavender | June into July | Gilligan, Madelon | .2017 |
| 'Theo's Blue' | Medium | Blue/Green | - | - | Hybrid | Med-Lavender | - | Zonneveld, Ben & Leydens, Theo | --NR-- |
| 'Theo's Green' | - | Med-Green | - | - | Unknown | - | - | Leydens, Theo & Van Eechaute, Danny | --NR-- |
| 'Theo's Red' | Medium | Med-Green | - | - | Hybrid | Med-Lavender | - | Leydens, Theo | --NR-- |
| 'Tickle Me Pink' | Small | Yellow | - | - | Hybrid | Light-Purple | July into August | Hack, J. & Stegeman, Bev & Stegeman, Dave | .2006 |
| 'Tinkle' | Miniature | Med-Green | Medial | White | Sport | Light-Purple | July | Unknown | --NR-- |
| 'To Dye For' | Large | Light-Green | Medial | White | Unknown | Near-White | July | Dye, Kay | .2017 |
| 'Tochi Ogon Iwa' | - | Yellow | - | - | Unknown | - | - | Unknown | --NR-- |
| 'Tokiwa Shisen' | Large | Med-Green | - | - | Sport | Pale-Lavender | - | Fukatsu, Shinya | --NR-- |
| 'Tokyo Spring' | Medium | Light-Green | | - | Hybrid | Pale-Lavender | July into August | Ragus, Gerhard & Ragus, Renate | .2020 |
| 'Tom Terrific' | Large | Yellow | - | - | Hybrid | Pale-Lavender | July into August | Solberg, Robert | .2019 |
| 'Totally Twisted' | Small | Light-Green | - | - | Hybrid | Pale-Lavender | August to October | Scheer, Alttara | --NR-- |
| 'Tremont Artisan' | Large | Med-Green | - | - | Unknown | - | - | Livingston, Ron | --NR-- |
| 'Tremont Ebony Angel' | Medium | Light-Green | - | - | Unknown | - | - | Livingston, Ron | --NR-- |
| 'Tremont Erubescence' | Small | Blue/Green | - | - | Unknown | - | - | Livingston, Ron | --NR-- |
| 'Tremont Mainstay' | Small | Blue/Green | - | - | Unknown | - | - | Livingston, Ron | --NR-- |
| 'Tremont Red Hacksaw' | - | - | - | - | Hybrid | - | - | Livingston, Ron | --NR-- |
| 'Tremont Red Rover' | Small | Yellow | - | - | Unknown | - | - | Livingston, Ron | --NR-- |
| 'Tremont Sho Girl' | Medium | Blue/Green | - | - | Unknown | - | - | Livingston, Ron | --NR-- |
| 'Tremont Something Dreamy' | Large | Blue/Green | - | - | Unknown | - | - | Livingston, Ron | --NR-- |
| 'Tremont Spice' | Medium | Med-Green | Marginal | Yellow | Unknown | Med-Lavender | - | Livingston, Ron | --NR-- |
| 'Trisha's Sunny Paradise' | Small | Yellow | - | - | Sport | Deep-Purple | July | McHugh, Ed | .2012 |
| 'Tropic Sunset' | Medium | Dark-Green | Medial | Yellow | Sport | - | - | Zilis, Mark | .2012 |
| 'Tweetypie' | Small | Yellow | - | - | Unknown | - | - | Unknown | --NR-- |
| 'Twist Tie' | Small | Blue/Green | - | - | Hybrid | Med-Lavender | - | Solberg, Robert | .2019 |
| 'Twizzler' | Medium | Blue/Green | - | - | Hybrid | Light-Purple | July into August | Elchuk, Kevin & Elchuk, Olga | .2015 |
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