| Cultivar Name | Plant Size | Leaf Color | Variegation | Var Color | Origin | Flower Color | Season | Source | Registered |
| 'Mañana' | Large | Dark-Green | | - | Unknown | Near-White | - | Tompkins, Chet & Ruh, Peter & Ruh, Jean | .2001 |
| 'Margaret' | Miniature | Med-Green | | - | Unknown | Light-Purple | August | Stone, David & Ruh, Peter | .1987 |
| 'Marie Curie' | Large | Med-Green | | - | Unknown | Pale-Lavender | July | Hensen, Karel & Ruh, Peter | .2002 |
| 'Marilyn Monroe' | Medium | Yellow | | - | Hybrid | Light-Purple | September | Hawes, James & Ruh, Peter | .2005 |
| 'Martin Van Buren' | Medium | Med-Green | | - | Hybrid | Pale-Lavender | September | Sugita, Hajime & Ruh, Peter | .2005 |
| 'Mary Jo' | Small | Blue/Green | | - | Unknown | Pale-Lavender | July | Stone, David & Ruh, Peter | .1987 |
| 'Maya' | Small | Dark-Green | Medial | Light Green | Sport | Pale-Lavender | July into August | Meissner, O. & Ruh, Peter | .1996 |
| 'Mayville' | Medium | Blue/Green | Medial | Yellow | Sport | Pale-Lavender | July | Ruh, Peter | .2003 |
| 'Memories' | Small | Med-Green | Streaked | Green | Hybrid | Light-Purple | August to September | Klose, Heinz & Ruh, Peter | .2002 .2018 |
| 'Mentor Gold' | Medium | Yellow | Marginal | White | Unknown | Light-Purple | August | Wayside Gardens & Ruh, Peter | .1978 |
| 'Merlin' (Ruh) | Small | Med-Green | Marginal | Yellow | Unknown | Unknown | - | Ruh, Peter | --NR-- |
| 'Mesa Fringe' | Large | Dark-Green | | - | Sport | Pale-Lavender | July | Ruh, Peter | .2000 |
| 'Michigander' | Large | Med-Green | Marginal | Yellow | Sport | Near-White | June into July | Struhar, Bill | .2018 |
| 'Middle Ridge' | Medium | Dark-Green | | - | Sport | Pale-Lavender | - | Boonstra, Richard & Lewis, C. & Ruh, Peter | .1979 |
| 'Mikawa-no-yuki' | Medium | Med-Green | | - | Hybrid | Pale-Lavender | August September October | Sugita, Hajime & Ruh, Peter | .1997 .2004 |
| 'Miki' | Large | Yellow | | - | Hybrid | Pale-Lavender | July into August | Zumbar, Wm & Ruh, Peter | .1991 |
| 'Millard Fillmore' | Large | Med-Green | | - | Unknown | Unknown | - | Ruh, Peter & Ruh, Jean | .2010 |
| 'Minna Blue' | Medium | Blue/Green | | - | Unknown | Unknown | August | Ruh, Jean | .1997 |
| 'Mirth' | Small | Light-Green | Marginal | Green | Hybrid | Med-Lavender | August to September | Matsubayashi, Nagao & Ruh, Peter & Ruh, Jean | .2001 |
| 'Missie Mouse' | Small | Med-Green | | - | Unknown | Light-Purple | August | Squires, Keith & Ruh, Peter | .1996 |
| 'Molly' | Large | Blue/Green | Marginal | Yellow | Sport | Med-Lavender | July into August | Ruh, Tim & Ruh, Peter & Ruh, Jean | .2005 |
| 'Moon over Lake Erie' | Medium | Dark-Green | Marginal | Yellow | Sport | Pale-Lavender | July | Ruh, Peter | .2005 |
| 'Moonlight Madness' | - | Yellow | Marginal | Yellow | Hybrid | Unknown | June into July | Sugita, Hajime & Ruh, Peter | .1999 |
| 'Mosel' | Medium | Med-Green | | - | Unknown | Med-Lavender | - | Klose, Heinz & Ruh, Peter & Ruh, Jean | .2008 |
| 'Mount Daisen' | Large | Dark-Green | | - | Nat-Sport | Pale-Lavender | June into July | Sugita, Hajime & Ruh, Peter & Ruh, Jean | .2005 |
| 'Mr Big' | Giant | Dark-Green | | - | Unknown | Near-White | July | Walden West Nursery & Ruh, Peter & Ruh, Jean | .2010 |
| 'Muted Moon' | Large | Med-Green | Marginal | Light Green | Sport | Pale-Lavender | July into August | Ruh, Peter | .1995 |
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