| Cultivar Name | Plant Size | Origin | Flower Color | Season | Source | Registered |
| 'Rambunctious' | Giant | Unknown | Near-White | July | Struhar, Bill | .2018 |
| 'Raucous Ruffles' | Medium | Hybrid | - | - | Dean, Don | .2008 |
| 'Ready Eddy' | Small | Unknown | - | - | Benedict, Dr Ralph (Herb) | --NR-- |
| 'Red Grange' | Medium | Unknown | - | - | Unknown | --NR-- |
| 'Red Wine Fries' | Medium | Hybrid | Med-Lavender | - | Van Wyke, Trudy | --NR-- |
| 'Redon Bleu' | Large | Unknown | - | - | Livingston, Ron | --NR-- |
| 'Regal Flame' | Large | Sport | Med-Lavender | July into August | Unknown | --NR-- |
| 'Regal Skies' | Large | Sport | Med-Lavender | July | Banyai, Bruce | .1999 |
| 'Regalia' | Large | Sport | Pale-Lavender | July into August | Anderson, Kenneth | .1992 |
| 'Reginald Kaye' | Medium | Unknown | Near-White | August | Ruh, Peter & Ruh, Jean | .2003 |
| 'Rembrandt Blue' | Large | Hybrid | Near-White | June into July | Moldovan, Steve | .1983 |
| 'Restless Sun' | Small | Unknown | - | - | Unknown | --NR-- |
| 'Reverend Mac' | Medium | Sport | Pale-Lavender | July into August | Van Eechaute, Danny | .2011 |
| 'Rhein' | Medium | Unknown | Pale-Lavender | August | Klose, Heinz & Ruh, Peter & Ruh, Jean | .2003 |
| 'Rhino Blue' | Large | Sport | Near-White | June into July | Rawson, Don | .2010 |
| 'Rhino Tuff' | Medium | Sport | Near-White | June into July | Rawson, Don | --NR-- |
| 'Rhubarb Blue' | Large | Unknown | - | - | Tompkins, Cynthia | --NR-- |
| 'Rhythm and Blues' | Small | Hybrid | Pale-Lavender | July into August | Johnson, Greg | .2004 |
| 'Ribbon Dancer' | - | Unknown | - | - | Terpening, Kent | --NR-- |
| 'Richland Blue' | Large | Unknown | Near-White | June into July | Wade, Van | .2007 |
| 'Richmond Blue' | Large | TC Sport | Near-White | June into July | Zumbar, Wm & Walek, Kevin | .2009 |
| 'Rick Strub' | Large | Hybrid | - | - | Zilis, Mark | --NR-- |
| 'Ridges' | Large | Hybrid | Near-White | July | Fisher, Eunice V. | --NR-- |
| 'Ripped' | Large | Unknown | Pale-Lavender | July | Soules, Marjorie & Goodenough, Rick | --NR-- |
| 'Rippled Blue Circles' | Large | Hybrid | - | - | Summers, Alex | --NR-- |
| 'Riptide' | Medium | Hybrid | Pale-Lavender | August | Sellers, Van | .1987 |
| 'Ritz' | Giant | Hybrid | Pale-Lavender | July into August | Livingston, Ron | --NR-- |
| 'River City Blues' | Large | Unknown | Pale-Lavender | June into July | Zilis, Mark & Ankney, Barry | .2018 |
| 'River Nile' | Giant | Hybrid | Near-White | June into July | Moldovan, Steve | .1983 |
| 'Robin of Loxley' | Medium | Unknown | Near-White | June into July | Schwarz, Jim | --NR-- |
| 'Robin's Pride' | Large | Unknown | - | June into July | Goodwin, Randy | .2000 |
| 'Rock and Roll' | Large | Sport | Near-White | June | Kuk, Bob | .1999 |
| 'Rock Garden Blue' | Large | Unknown | - | - | Tompkins, Chet | --NR-- |
| 'Rock of Ages' | Giant | Sport | Pure-White | June into July | Ward, Dr Dick & Ward, Jane | .2009 |
| 'Rock of Gibralter' | Large | Sport | - | June into July | Zilis, Mark | .2010 |
| 'Rock Star Land' | Medium | Hybrid | - | - | Stadden, Josh | --NR-- |
| 'Rocknoll Blue Dwarf' | Miniature | Unknown | - | August | Saur, B. & Ruh, Peter | .1996 |
| 'Rock'n'Roll Heart' | Large | Unknown | - | - | Port, Linda | --NR-- |
| 'Rocky Fork' | Medium | Unknown | Pale-Lavender | June into July | Ward, Dr Dick & Ward, Jane | .2003 |
| 'Roderick' | Giant | Unknown | Pale-Lavender | - | O'Harra, Russ | .1999 |
| 'Rolling Thunder' | Large | Unknown | Near-White | June into July | Brashear, Carol | --NR-- |
| 'Roscoe' | Giant | Hybrid | Near-White | June | Wade, Van | .1999 |
| 'Rosedale Babe' | Large | Hybrid | Near-White | July into August | Hadrava, Jerry | .2000 |
| 'Rosedale Black Hole' | Large | Hybrid | Pale-Lavender | June into July | Hadrava, Jerry | .2000 |
| 'Rosedale Black Ice' | Large | Hybrid | Near-White | June into July | Hadrava, Jerry | .1999 |
| 'Rosedale Catcher's Mitt' | Large | Hybrid | Light-Purple | July into August | Hadrava, Jerry | .2000 |
| 'Rosedale Dewy' | Medium | Hybrid | Near-White | June into July | Hadrava, Jerry | .1999 |
| 'Rosedale Glacier Ice' | Small | Hybrid | - | - | Hadrava, Jerry | .1999 |
| 'Rosedale John Stratton' | Medium | Hybrid | - | - | Hadrava, Jerry | .1999 |
| 'Rosedale Mr. Blue Jeans' | Large | Hybrid | Pure-White | July | Hadrava, Jerry | .1999 |
| 'Rosedale Pickles' | Medium | Hybrid | Near-White | July | Hadrava, Jerry | .1999 |
| 'Rosedale Rain Catcher' | Large | Hybrid | Near-White | June | Hadrava, Jerry | .2000 |
| 'Rosedale Richie Vallens' | Giant | Hybrid | Pale-Lavender | July | Hadrava, Jerry | .2000 |
| 'Rosedale Rob Lucomus' | Large | Unknown | Near-White | June | Hadrava, Jerry | --NR-- |
| 'Rosedale Rosette' | Medium | Hybrid | - | - | Hadrava, Jerry | .1999 |
| 'Rosedale Spoons' | Medium | Unknown | Near-White | July | Hadrava, Jerry | .1999 |
| 'Rosedale Tractor Seat' | Large | Hybrid | Near-White | June | Hadrava, Jerry | .1999 |
| 'Rosy' | Medium | Unknown | - | - | Klose, Heinz | --NR-- |
| 'Rotunda' | Medium | Hybrid | Pale-Lavender | June | Savory, Robert | .1998 |
| 'Rough Knight' | Small | Hybrid | Med-Lavender | August | Beilstein, Doug & Beilstein, Mardy | .2013 |
| 'Rough Rider' | Medium | Unknown | - | - | Beilstein, Doug | --NR-- |
| 'Rough Waters' | Large | Hybrid | Near-White | June into July | Armstrong, Maxine | .1969 |
| 'Roundabout' (Savory) | Medium | Hybrid | Pale-Lavender | June | Savory, Robert | .1988 |
| 'Rounder' | Small | Unknown | - | - | Benedict, Dr Ralph (Herb) | --NR-- |
| 'Roundhouse Blues' | Large | Unknown | Near-White | June into July | Micheletti, Tom | .1998 |
| 'Rowan My Boat' | Large | Hybrid | Med-Lavender | June into July | Beilstein, Doug & Beilstein, Mardy | .2018 |
| 'Roxton Falls' | Giant | Unknown | - | - | Bastille, Jocelyne | --NR-- |
| 'Royal Quilt' | Large | Hybrid | Near-White | June into July | Caprice Farm Nursery & Rogers, Allan | .1988 |
| 'Ruby Wedding' | - | Unknown | - | - | Jolliffe, Thomas | --NR-- |
| 'Ruffian' (Arett) | Large | Unknown | - | - | Arett, Anne | .2009 |
| 'Ruffled Mouse Ears' | Miniature | Sport | Med-Lavender | July | Zilis, Mark | .2011 |
| 'Ruffles Galore' | Medium | Unknown | - | June into July | Powell, Loleta & Walek, Kevin | .2009 |
| 'Ruffles n Ridges' | Giant | Hybrid | Med-Lavender | June into July | Fox, Bob & Fox Hosta Farm | .2018 |
| 'Rupiana' | Large | Hybrid | - | - | Balitewicz, Bob | --NR-- |
| 'Russell Square' | Medium | Unknown | - | - | Crockett, Clyde | --NR-- |
| 'Rusty's Wave' | Giant | Unknown | - | - | Rouillier, Denis | --NR-- |
| 'Ruth' | Medium | Sport | Pale-Lavender | June into July | Schwarz, Jim & Schwarz, Karen | .2014 |
| 'Ryan's Big One' | Giant | Hybrid | Near-White | June into July | Englerth, Lawrence & Ryan (Unknown) | .1982 |
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