No. | Cultivar Name | Plant Size | Leaf Color | Variegation | Var Color | Origin | Flower Color | Season | Source | Registered |
1
| 'O Kanzashi' | Medium | Med-Green | | - | Sport | Light-Purple | - | Unknown | --NR-- |
2
| 'Oberland Thin Line' | Medium | Blue/Green | Marginal | Yellow | Sport | Pale-Lavender | July into August | Rank, Stefan | --NR-- |
3
| 'October Sky' | Medium | Blue/Green | | - | Hybrid | Near-White | August to September | Dean, Don | .2008 |
4
| 'Odd Goddess' | Medium | Med-Green | | - | Hybrid | Pale-Lavender | June into July | Kwick, Charles | .2017 |
5
| 'Ogon Hime Tokudama' | Small | Light-Green | | - | Unknown | Pale-Lavender | June into July | Unknown & Ruh, Peter | .2002 .2018 |
6
| 'Ogon Iwa' | Medium | Yellow | | - | Unknown | Med-Lavender | August to September | Unknown | --NR-- |
7
| 'Ogon Sudare' | Small | Yellow | | - | Unknown | Pale-Lavender | July | Unknown & Ruh, Peter | .2002 .2018 |
8
| 'Ogon Tachi' | Large | Light-Green | | - | Unknown | Deep-Purple | August | Unknown & Ruh, Peter | .2002 .2018 |
9
| 'Ogon Tsushima' | Medium | Yellow | | - | Unknown | Light-Purple | July into August | Unknown & Ruh, Peter | .2002 .2018 |
10
| 'Ohh! Blue Beacon' | Small | Blue/Green | | - | Unknown | Near-White | June into July | Schulz, Ed | .2013 |
11
| 'Ohh! Blue Bounty' | Large | Blue/Green | | - | Unknown | Near-White | June into July | Schulz, Ed | .2011 |
12
| 'Ohh! Blue Bruiser' | Giant | Blue/Green | | - | Unknown | Med-Lavender | - | Schulz, Ed | .2011 |
13
| 'Ohh! Blue Granite' | Medium | Blue/Green | | - | Unknown | Near-White | June into July | Schulz, Ed | .2018 |
14
| 'Ohh! His Blue Eyes' | Large | Blue/Green | | - | Unknown | Med-Lavender | June into July | Schulz, Ed | .2017 |
15
| 'Ohh! Jewell' | Large | Yellow | | - | Unknown | Near-White | June into July | Schulz, Ed | .2017 |
16
| 'Ohh! Viola' | Medium | Yellow | | - | Unknown | Near-White | June into July | Schulz, Ed | .2015 |
17
| 'OHS Margot's Delight' | Medium | Blue/Green | | - | Sport | Pale-Lavender | July into August | Ontario Hosta Society | --NR-- |
18
| 'Ojibway' | Medium | Blue/Green | | - | Unknown | Unknown | Unknown | Wade, Van | --NR-- |
19
| 'Old Bill' | Giant | Blue/Green | | - | Hybrid | Pale-Lavender | June into July | Gilligan, Madelon | .2012 |
20
| 'Old Ironsides' | Giant | Light-Green | | - | Sport | Med-Lavender | July | Summers, Alex | --NR-- |
21
| 'Old Smoky' | Large | Med-Green | | - | Hybrid | Near-White | June into July | McDonell, Harold | .2014 |
22
| 'One Fine Day' | Medium | Med-Green | Marginal | Yellow | Hybrid | Near-White | June into July | Ward, Dr Dick & Ward, Jane | .2012 |
23
| 'Orphan Train Rider' | Small | Light-Green | | - | Unknown | Med-Lavender | July into August | Kwick, Charles | .2017 |
24
| 'Orphan Train Ruffian' | Medium | Dark-Green | | - | Hybrid | Pale-Lavender | July into August | Kwick, Charles | .2017 |
25
| 'Osiris Ovation' | Large | Yellow | | - | Unknown | Pale-Lavender | - | Fafard, Serge | --NR-- |
26
| 'Otara's Angel' | Large | Dark-Green | Marginal | Yellow | Sport | Near-White | June into July | Johns, Eddie | --NR-- |
27
| 'Ottawa' | Large | Med-Green | | - | Unknown | Unknown | Unknown | Wade, Van | --NR-- |
28
| 'Ovalwood' | Large | Blue/Green | | - | Hybrid | Near-White | July | Beilstein, Doug & Beilstein, Mardy | .2012 |
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