| Cultivar Name | Plant Size | Leaf Color | Variegation | Var Color | Origin | Flower Color | Season | Source | Registered |
| 'Kasseler Blue' | Medium | Blue/Green | - | - | Unknown | - | - | Klose, Heinz & Ruh, Peter & Ruh, Jean | .2008 |
| 'Kasseler Gold' | Medium | Yellow | - | - | Hybrid | Pale-Lavender | June into July | Klose, Heinz & Ruh, Peter & Ruh, Jean | .2003 |
| 'Kayak' | Large | Blue/Green | - | - | Unknown | Pale-Lavender | July | Black, Gwen & Ruh, Peter | .1999 |
| 'Kelsey' | Medium | Med-Green | - | - | Hybrid | Pale-Lavender | August to October | Williams, Frances & Ruh, Peter | .1996 |
| 'Kerplunk' | Medium | Yellow | - | - | Hybrid | Pale-Lavender | August | Benedict, Dr Ralph (Herb) & Ruh, Peter | .2005 |
| 'Kifukurin Hyuga' | Small | Blue/Green | Marginal | Yellow | Unknown | Pale-Lavender | August to September | Unknown & Ruh, Peter | .2002 .2018 |
| 'Kifukurin Ko Mame' | Miniature | Med-Green | Marginal | White | Sport | Light-Purple | August to September | Watanabe, Kenji & Ruh, Peter | .2002 .2018 |
| 'Kifukurin Ubatake' | Miniature | Dark-Green | Marginal | White | Sport | Light-Purple | August | Unknown & Ruh, Peter | .2002 .2018 |
| 'Kinbotan' | Miniature | Med-Green | Marginal | Yellow | Sport | Med-Lavender | August to September | Unknown & Ruh, Peter | .2002 .2018 |
| 'Kinbuchi Tachi' | Large | Dark-Green | Marginal | White | Sport | Light-Purple | August to September | Unknown & Ruh, Peter | .2002 .2018 |
| 'King James' | Large | Med-Green | - | - | Hybrid | Near-White | June into July | Krossa, Gus & Ruh, Peter | .1992 |
| 'King Michael' | Giant | Med-Green | - | - | Hybrid | Near-White | June | Krossa, Gus & Summers, Alex & Ruh, Peter | .1992 |
| 'Kinki' | Large | Yellow-Gold | - | - | Unknown | Med-Lavender | July into August | Ruh, Peter | .2002 .2018 |
| 'Klopping Variegated' | Medium | Blue/Green | Marginal | White | Unknown | Pale-Lavender | July | Klopping, Minnie & Ruh, Peter | .1988 |
| 'Ko Mame' | Miniature | Light-Green | - | - | Unknown | Med-Lavender | September | Unknown & Ruh, Peter | .2002 .2018 |
| 'Kokuryu' | Medium | Med-Green | - | - | Unknown | Near-White | October | Nakayama, Toyozo & Kurasawa, Tsuneo & Ruh, Peter | .2000 |
| 'Konkubine' | Medium | Yellow | - | - | Unknown | Pale-Lavender | July | Klose, Heinz & Ruh, Peter & Ruh, Jean | .2005 |
| 'Krossa Broad Band' | Large | Blue/Green | Marginal | Yellow | Sport | Pale-Lavender | July | Krossa, Gus & Ruh, Peter | .1991 |
| 'Krossa Regal White Variegation' | Giant | Blue/Green | Streaked | White | TC Sport | Med-Lavender | July into August | Ruh, Peter | --NR-- |
| 'Krossa Regal Yellow Variegation' | Giant | Blue/Green | Streaked | Yellow | TC Sport | Med-Lavender | July into August | Ruh, Peter | --NR-- |
| 'Kyoto' | Medium | Med-Green | - | - | Hybrid | Med-Lavender | August to October | Sugita, Hajime & Ruh, Peter | .2001 |
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