| Cultivar Name | Plant Size | Leaf Color | Variegation | Var Color | Origin | Flower Color | Season | Source | Registered |
| 'I'm My Kid's Mom' | Medium | Med-Green | Streaked | White | Hybrid | Pale-Lavender | July into August | Elslager, Ed | .2003 |
| 'I'm So Pretty' | Large | Blue/Green | - | - | Sport | Pale-Lavender | July | Schwarz, Jim | .2003 |
| 'Macazoo' | Giant | Dark-Green | - | - | Unknown | - | - | Unknown | --NR-- |
| 'MacBenedict' | Large | Blue/Green | Streaked | Yellow | Hybrid | Pale-Lavender | July | Elslager, Ed | .2002 |
| 'Made from Scratch' | Medium | Med-Green | Marginal | White | Hybrid | Pale-Lavender | July | Asch, Stuart | .2005 |
| 'Made You Look' | Medium | Yellow | - | - | Hybrid | Pure-White | July | Asch, Stuart | .2000 |
| 'Mama's Gold' | Medium | Yellow | - | - | Hybrid | Pure-White | July | Snyder, Ron | .1999 |
| 'Mandelbrot Set' | Giant | Light-Green | - | - | Hybrid | - | June | Nyikos, Frank | .2011 |
| 'Mango Tango' | Large | Med-Green | Medial | Yellow | Sport | Pale-Lavender | July | Kinman, Eric | .2007 |
| 'Mardi Gras Parade' | Medium | Blue/Green | Streaked | Yellow | Hybrid | Near-White | July | Vaughn, Kevin | --NR-- |
| 'Margin of Error' | Medium | Med-Green | Marginal | Creamy White | Sport | Pale-Lavender | August | Kuk, Bob | .1995 |
| 'Mary's White Backside' | Large | Blue/Green | Streaked | Yellow | Unknown | - | - | Unknown | --NR-- |
| 'Mean Green Thing' | Medium | Med-Green | - | - | Sport | - | - | Fransen, Marco | --NR-- |
| 'Megababy' | Small | Med-Green | Streaked | Yellow | Unknown | | | Russo, Dave | --NR-- |
| 'Megacup' | Medium | Blue/Green | Streaked | Speckles | Hybrid | Pale-Lavender | July into August | Elslager, Ed | .2000 |
| 'Merci Marci' | Small | Blue/Green | Marginal | White | Unknown | - | July into August | Asch, Stuart | .2008 |
| 'Merry-go-round' | Giant | Med-Green | - | - | Hybrid | - | - | Elslager, Ed | .1999 |
| 'Midlife Crisis -Tummy Tuck' | Small | Blue/Green | Medial | Yellow | TC Sport | Pale-Lavender | July into August | Wilson, Glenn | --NR-- |
| 'Mighty Moe' | Small | Dark-Green | Medial | White | Sport | Light-Purple | June into July | Silvers, Bill | .2009 |
| 'Mighty Moe Supreme' | Miniature | Med-Green | Medial | White | Sport | Pale-Lavender | June into July | Wade, Van | .2015 |
| 'Mike's Big Winky' | Large | Dark-Green | - | - | Unknown | - | - | Unknown | --NR-- |
| 'Mildred's Smile' | Medium | Yellow | - | - | Hybrid | Near-White | July | Nyikos, Frank | .2007 |
| 'Million Dollar Baby' | Large | Blue/Green | Medial | Yellow | Hybrid | Near-White | July into August | Elslager, Ed | .2005 |
| 'Mini Ha Ha' | Small | Light-Green | Marginal | Yellow | Hybrid | Light-Purple | July | Benedict, Dr Ralph (Herb) | --NR-- |
| 'Mini Skirt' | Small | Dark-Green | Marginal | White | Sport | Pale-Lavender | June into July | Martinez, Maria & Walters Gardens | .2013 |
| 'Minute After a Rainy Sunset' | Medium | Light-Green | Streaked | Yellow | Sport | Pale-Lavender | July into August | McHugh, Ed | .2010 |
| 'Mishmash' | Small | Med-Green | Streaked | White | Unknown | Near-White | August | Kuroishi Wildflower Farm & Van Eechaute, Danny | --NR-- |
| 'Miss Missey' | Medium | Med-Green | Medial | White | Sport | Med-Lavender | August | Wrede, Arthur | .2006 |
| 'Moldy Muffins' | Medium | Med-Green | - | - | Sport | Med-Lavender | July | Unknown | --NR-- |
| 'Moolah' | Miniature | Dark-Green | Marginal | Yellow | Hybrid | Pale-Lavender | June into July | Goodwin, Randy | .2013 |
| 'Moose Bait' | Small | Light-Green | - | - | Hybrid | - | - | Williams, Glenn | --NR-- |
| 'Mossy Cascades' | Large | Dark-Green | Streaked | White | Unknown | - | - | Unknown | --NR-- |
| 'Mr. Mister' | - | Med-Green | Streaked | Yellow | Unknown | - | - | Unknown | --NR-- |
| 'Mucho Macho' | Small | Med-Green | - | - | Hybrid | Med-Lavender | August to September | Philips, Hugo | --NR-- |
| 'Mulah' | - | - | - | - | Duplicate | - | - | Duplicate Name | --NR-- |
| 'Mumsie' | Giant | Med-Green | - | - | Unknown | Pale-Lavender | July into August | Hiselman, Paula & Krul, Nancy | .1999 |
| 'Mutant Ninja' | Miniature | Dark-Green | Streaked | Yellow | Sport | Deep-Purple | July | Janssen, Bill & Walek, Kevin | .2009 |
| 'Mutated Ghost' | Small | Blue/Green | Streaked | Yellow | Unknown | | | Van Eechaute, Danny | --NR-- |
| 'Mutley's Rest' | Large | Blue/Green | Medial | Yellow | Sport | Near-White | June into July | Orlando, John | .2001 |
| 'My Child Insook' | Medium | Med-Green | Medial | White | Sport | Pale-Lavender | July into August | Benedict, Dr Ralph (Herb) & Benedict, Dorothy | .1995 |
| 'My Fine Feathered Friend' | Large | Med-Green | Marginal | Yellow | Sport | Near-White | July into August | Seaver, Charles | .2012 |
| 'My Forbidden Romance' | Medium | Med-Green | Marginal | Blue-Green | Sport | Med-Lavender | July into August | Stadden, Josh | --NR-- |
| 'My Lucky Star' | Medium | Blue/Green | Marginal | White | Sport | Med-Lavender | July into August | Heemskerk, Gerardus | .2012 |
| 'My Old Flame' | Small | Light-Green | Marginal | White | Hybrid | Pale-Lavender | June | Ward, Dr Dick & Ward, Jane | .2012 |
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