| Cultivar Name | Plant Size | Leaf Color | Variegation | Var Color | Origin | Flower Color | Season | Source | Registered |
| 'Rambunctious' | Giant | Blue/Green | | - | Unknown | Near-White | July | Struhar, Bill | .2018 |
| 'Raspberry Parfait' | Large | Med-Green | | - | Hybrid | Light-Purple | September | Ruh, Peter | .1998 |
| 'Red Legs' | Medium | Dark-Green | | - | Hybrid | Unknown | September | Sugita, Hajime & Ruh, Peter | .1999 |
| 'Reginald Kaye' | Medium | Blue/Green | | - | Unknown | Near-White | August | Ruh, Peter & Ruh, Jean | .2003 |
| 'Rhein' | Medium | Blue/Green | | - | Unknown | Pale-Lavender | August | Klose, Heinz & Ruh, Peter & Ruh, Jean | .2003 |
| 'Rippled Honey' | Large | Med-Green | | - | Hybrid | Light-Purple | August | Benedict, Dr Ralph (Herb) & Ruh, Peter | .2005 |
| 'Rising Surf' | Medium | Med-Green | Marginal | White | Unknown | Pale-Lavender | July | Ruh, Peter | --NR-- |
| 'Robust Giant' | Large | Light-Green | | - | Unknown | Unknown | June into July | Ruh, Peter & Ruh, Jean | .2005 |
| 'Rock Happy' | Medium | Med-Green | | - | Hybrid | Med-Lavender | August | Ruh, Peter | .1992 |
| 'Rocknoll Blue Dwarf' | Miniature | Blue/Green | | - | Unknown | Unknown | August | Saur, B. & Ruh, Peter | .1996 |
| 'Royal Rhubarb' | Large | Med-Green | | - | Hybrid | Light-Purple | July into August | Pallone, D. & Ruh, Peter & Ruh, Jean | .2005 |
| 'Rutherford Birchard Hayes' | Medium | Light-Green | | - | Unknown | Med-Lavender | - | Ruh, Peter & Ruh, Jean | .2010 |
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