| Cultivar Name | Plant Size | Origin | Flower Color | Season | Source | Registered |
| 'Ugly' | Small | Unknown | - | - | Unknown | --NR-- |
| 'Uguis' | Large | Unknown | Light-Purple | July into August | Unknown & Walek, Kevin | .2009 .2018 |
| 'Ulan' | Medium | Hybrid | Light-Purple | - | Becherer, Josef | --NR-- |
| 'Ulysses S Grant' | Large | Unknown | Pale-Lavender | July | Sugita, Hajime & Ruh, Peter | .2001 |
| 'Unazuki Dwarf' | Small | Sport | Near-White | August to October | Unknown | --NR-- |
| 'Unazuki Soules' | Small | Sport | - | - | Soules, Marjorie | --NR-- |
| 'Uncle Albert' | Large | Hybrid | - | - | Wasitis, Chick | .2008 |
| 'Undertow' | Small | Hybrid | Med-Lavender | August to September | Seaver, Charles | .2012 |
| 'Undine' | Giant | Hybrid | Pale-Lavender | June into July | Schuster, Eberhard & Syre-Herz, Ursula | --NR-- |
| 'Unducosa' | Medium | Hybrid | Med-Lavender | July | Summers, Alex & The American Hosta Society | .1986 |
| 'Undulata Erromena' | Large | Sport | Pale-Lavender | July | The American Hosta Society | .1987 |
| 'Undulata Nana' | Small | Unknown | - | - | Klose, Heinz | --NR-- |
| 'Unexpected Song' | Large | Sport | Pure-White | July into August | Wilkins, Dr Jim | .2000 |
| 'Uniquely Rails to Trails' | Giant | Sport | Pale-Lavender | July into August | Rosenberg, Marlene | --NR-- |
| 'Unruly Child' | Medium | Unknown | - | July into September | Avent, Tony | .2012 |
| 'Upbeat' | Giant | Hybrid | Pale-Lavender | July | Ruh, Peter | .2000 |
| 'Uptown Girl' | Large | Hybrid | Light-Purple | September | Hansen, Hans | .2007 |
| 'Urajiro Amagi Iwa' | Medium | Sport | - | September | Unknown & Walek, Kevin | .2009 |
| 'Urajiro Hachijo' | Medium | Sport | Light-Purple | September | Unknown | --NR-- |
| 'Urajiro Iwa' | Medium | Sport | Light-Purple | September | Unknown | --NR-- |
| 'Urajiro Izu Iwa' | Small | Sport | Med-Lavender | August to September | Unknown & Walek, Kevin | .2009 |
| 'Urajiro Ko Iwa' | Miniature | Hybrid | - | - | Watanabe, Kenji | --NR-- |
| 'Urajiro Musashino' | Small | Sport | Light-Purple | August to September | Unknown | --NR-- |
| 'Urajiro Oba' | Large | Sport | - | - | Unknown | --NR-- |
| 'Urajiro Sudare' | Large | Unknown | - | - | Unknown | --NR-- |
| 'Urajiro Ubatake' | Small | Sport | Light-Purple | July | Watanabe, Kenji | --NR-- |
| 'Urajiro', H. rupifraga | Small | Sport | Deep-Purple | - | Nigishi | --NR-- |
| 'Urchin' | Small | Hybrid | Med-Lavender | July into August | Beilstein, Doug & Beilstein, Mardy | .2013 |
| 'Utah Kid' | Small | Unknown | - | - | Unknown | --NR-- |
| 'Uzu-no-mai' | Miniature | Unknown | Light-Purple | August | Unknown & Walek, Kevin | .2009 |
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