| Giant Size Hostas | Leaf Color | Variegation | Var Color | Origin | Flower Color | Season | Source | Registered |
| 'Ka-ching' | Dark-Green | - | - | Unknown | Pale-Lavender | June into July | Zolock, Steve & Sarah | .2011 |
| 'Kaiapoi' | Blue/Green | - | - | Hybrid | Near-White | June into July | Gilligan, Madelon | .2012 |
| 'Kalyn's Joy' | Blue/Green | | - | Hybrid | Near-White | June into July | Hurlbert, D. | .2019 |
| 'Karen Deborah' | Blue/Green | - | - | Unknown | Pale-Lavender | June | Simpers, Lucille | --NR-- |
| 'Keel' | Blue/Green | - | - | Hybrid | Near-White | June into August | Gilligan, Madelon | .2012 |
| 'Kerry Man' | Blue/Green | - | - | Nat-Sport | Near-White | June into July | Gilligan, Madelon | .2015 |
| 'Key West' | Yellow | - | - | Hybrid | Near-White | June into July | Petryszyn, Olga | .1999 |
| 'Khaki Krush' | Med-Green | - | - | Hybrid | Pale-Lavender | July into August | Heims, Dan | --NR-- |
| 'Kim' | Blue/Green | - | - | Hybrid | - | June into July | Kwick, Charles | .2016 |
| 'Kimmie Q' | Blue/Green | - | - | Hybrid | Near-White | June into July | Kwick, Charles | .2017 |
| 'King John' | Blue/Green | - | - | Hybrid | - | July into August | Schwarz, Jim | .2010 |
| 'King Michael' | Med-Green | - | - | Hybrid | Near-White | June | Krossa, Gus & Summers, Alex & Ruh, Peter | .1992 |
| 'King of the Hill' | Blue/Green | Streaked | Yellow | Hybrid | Near-White | July into August | Elslager, Ed | .2005 |
| 'King Tucker' | Dark-Green | - | - | Hybrid | - | August to September | Kwick, Charles | .2016 |
| 'King's Beacon of Light' | Light-Green | - | - | Unknown | - | - | King, Herb | --NR-- |
| 'Kingsize' | Dark-Green | - | - | Nat-Sport | Pale-Lavender | June | Van Eechaute, Danny | .2013 |
| 'Kiwi Ingenuity' | Blue/Green | Streaked | Yellow | Nat-Sport | Near-White | June into July | Sligh, Barry | --NR-- |
| 'Kiwi Midnight' | Blue/Green | - | - | Unknown | - | - | Sligh, Barry | --NR-- |
| 'Krossa Regal' | Blue/Green | - | - | Unknown | Pale-Lavender | July into August | Krossa, Gus & Summers, Alex | .1980 |
| 'Krossa Regal Splashed' | Blue/Green | Streaked | White | Nat-Sport | Med-Lavender | July into August | Miller, Jeff | --NR-- |
| 'Krossa Regal Streaked' | Blue/Green | Streaked | White | Nat-Sport | Med-Lavender | July into August | Lydell, Ransom | --NR-- |
| 'Krossa Regal White Variegation' | Blue/Green | Streaked | White | TC Sport | Med-Lavender | July into August | Ruh, Peter | --NR-- |
| 'Krossa Regal Yellow Variegation' | Blue/Green | Streaked | Yellow | TC Sport | Med-Lavender | July into August | Ruh, Peter | --NR-- |
| 'Kuk's Forest' | Dark-Green | Marginal | Yellow | Hybrid | - | - | Kuk, Bob | --NR-- |
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