Total number of azaleas: [196]
| Cultivar | Group | Ref | Type | Color | Bloom | |
|---|---|---|---|---|---|---|
|
‘O Nuts’
('Oh Nuts') |
Hager | Galle85 | evg | |||
|
‘O-guruma’
('Kin-yori', 'Itoguruma', 'Yori-kurenai') |
Tsutsuji | IRRC04 | evg | |||
| O7G | Gable | Tingle57 | evg | |||
| ‘Oakton’ | Virginia Royalty Series | Galle87 | evg | Pink-Dark,Red | Early Midseason | |
| ‘Oakton’ | Ring | Galle87 | evg | Pink | ||
|
‘Obergartner Nietner’
('Oberhofgartner Nietner') |
Mollis | Galle87 | dec | |||
| ‘Oberon’ | Kaempferi | Galle85 | evg | |||
| ‘Oboro Tsuki’ | Satsuki | Galle85 | evg | |||
| ‘Oborozuki’ | Satsuki | SatDict97 | evg | |||
|
‘Obsession’
(HS 84-33-05) |
Holly Springs | Vines90 | evg | Purple | Midseason |
|
‘Obtusum’
('Kirishima Tsutsuji', 'Ramentaceum', Kirishima Azalea) |
Species | Galle85 | evg | |||
|
R. occidentale
(Pacific Azalea, Smooth Azalea, Western Azalea) |
Species | Galle85 | dec | ||
| ‘Ocean Gold’ | Occidentale | Galle85 | dec | |||
| ‘Ocean Mist’ | Occidentale | Galle85 | dec | |||
| ‘Ochoco’ | Slonecker | Galle85 | dec | |||
| ‘Ochroleuca’ | Ghent | Galle87 | dec | |||
| ‘Oconee Arrow’ | Towe | Galle87 | dec | |||
| ‘October Pink’ | Aus. & NZ | Galle85 | evg | |||
| ‘Odilia’ | Boskoop | IRRC | evg | Red | Early Midseason | |
| ‘Odin’ | Mollis | Galle87 | dec | |||
| ‘Odoratum’ | Unknown | Galle85 | azd | |||
| ‘Oegawa’ | Satsuki | SatDict97 | evg | |||
| ‘Oester’ | Arendsii | Galle87/IRRC04 | evg | Rose | ||
| ‘Ogi’ | Satsuki | SatDict97 | evg | |||
| ‘Ogi-no-hana’ | Satsuki | SatDict97 | evg | |||
|
‘Ogi-no-odorikaraki’
('Kojo-no-odorikaraki', 'Kojo-no-odorikaraski', 'Ogi-no-odorikaraski') |
Kurume | Galle85 | evg | |||
|
‘Ogikasane’
('Cherryblossom') |
Kurume | Galle85 | evg | ||
| ‘Ogon-no-mai’ | Satsuki | Galle85 | evg | |||
| ‘Ogon-no-tsuki’ | Satsuki | Galle85 | evg | |||
| ‘Oh Golly’ | Hager | ARS-Azalea Chapter | evg | Early Midseason | ||
|
‘Oh Heaven’ | Hager | evg | Midseason | ||
|
‘Oh Heck’ | Hager | evg | |||
|
‘Oh Look’ | Hager | evg | |||
|
‘Oh My’ | Satsuki | Galle85 | evg | Late | |
|
‘Oh Nuts’ | Hager | evg | Midseason | ||
| ‘Ohio’ | Chisolm-Merritt | Galle85 | evg | Pink-Dark | ||
| ‘Ohirayama’ | Satsuki | SatDict97 | evg | |||
| ‘Oho’ | Satsuki | SatDict97 | evg | |||
| ‘Oimatsu’ | Kurume | Galle87 | evg | |||
| ‘Oimatsu’ | Satsuki | SatDict97 | evg | |||
|
‘Oino-mezame’
('Melody', Wilson #25) |
Kurume/Wilson50 | Galle85 | evg | Purple | |
| ‘Ojikanishiki’ | Satsuki | SatDict97 | evg | |||
| ‘Oka’ | Satsuki | SatDict97 | evg | |||
| ‘Okan’ | Satsuki | SatDict97 | evg | |||
| ‘Oki Island’ | Greer | IRRC | dec | |||
| ‘Okina Nishiki’ | Satsuki | Galle85 | evg | |||
| ‘Okina-no-tomo’ | Satsuki | SatDict97 | evg | |||
| ‘Okinamaru’ | Satsuki | SatDict97 | evg | |||
|
‘Okura-no-tuki’
('Okura-no-tsuki') |
Satsuki | SatDict97 | evg | |||
|
‘Old Faithful’
(136G) |
Gable | Galle87/IRRC | evg | Purplish-Red | Early Midseason |
| ‘Old Gold’ | Exbury | Galle85 | dec | |||
|
‘Old Rose’
(AGY-5) |
Aromi | Azalean25:2 | dec | Rose | |
| ‘Old Wine’ | Coolidge | Galle85 | evg | |||
| ‘Olde Gold’ | Lazy K | AmAz04 | dec | |||
|
R. oldhamii | Species | Galle85 | evg | Orange,Red | Early |
|
‘Olga Niblett’
(T50-8) |
Robin Hill | Galle85 | evg | White | ||
| ‘Olinda’ | Aus. & NZ | Galle85 | evg | |||
| ‘Olympia’ | Aus. & NZ | Galle85 | evg | |||
| ‘Olympic Sunrise’ | Unknown | Roslyn95 | dec | |||
|
‘Omega’
('Antoine') |
Deckert | Galle85 | evg | |||
|
‘Omen’ | Glenn Dale | Galle85 | evg | White | Late Midseason |
| ‘Omoi-no-Maku’ | Satsuki | Galle85 | evg | |||
| ‘Omoigawa’ | Satsuki | SatDict97 | evg | |||
|
‘Omoine’
('Dame Lavender', Wilson #26) |
Kurume/Wilson50 | Galle85 | evg | Purple | ||
| ‘Omurasaki’ | Mucronatum | evg | ||||
|
‘Omurasaki’
('Calycinum', 'Kumagi-yodagawa', 'O-omurasaki', phoeniceum var. calycinu) |
Phoeniceum | Galle85 | evg | Maroon | ||
| ‘On-No Sura’ | Kurume | IRRC04 | evg | Lavender | ||
| ‘One-O-One’ | EX-Childers | Galle85 | dec | |||
| ‘Only One Earth’ | Aus. & NZ | Galle85 | evg | |||
| ‘Onmei’ | Satsuki | SatDict97 | evg | |||
| ‘Onno Sora’ | Kurume | Galle87 | evg | |||
|
‘Onsho’ | Satsuki | Galle85 | evg | ||
|
‘Onyo’ | Satsuki | Galle87 | evg | Midseason | |
|
‘Oochiyama’
(NA 45416) |
Kurume | IRRC04 | evg | Red,Purple | |
|
‘Oogocho’ | Kurume | IRRC04 | evg | Red | |
|
‘Oops’ | Hager | evg | Midseason | ||
| ‘Oouchi Yama’ | Kurume | Galle85 | evg | |||
| ‘Oouchiyama’ | Kurume | evg | ||||
|
‘Opal’
(L-1) |
Linwood Hardy | Galle85 | evg | Purple,Red | |
|
‘Opera’ | Glenn Dale | Galle85 | evg | Pink | Early Midseason |
| ‘Ophelia’ | Aus. & NZ | Galle85 | evg | |||
| ‘Ophelia’ | Kaempferi | Galle85 | evg | |||
| ‘Ophelia’ | Mollis | Galle87 | dec | |||
| ‘Ophelila’ | Matous | Galle87 | evg | |||
| ‘Opherie’ | Ghent | Galle87 | dec | |||
| ‘Optima’ | Amoena | Galle85 | evg | |||
| ‘Optima’ | Ghent | Galle87 | dec | |||
| ‘Opus One’ | Prinophyllum | Galle87 | dec | |||
|
‘Oracle’ | Glenn Dale | Galle85 | evg | ||
|
‘Orage’
('SS 37') |
Deckert | Galle85 | evg | |||
| ‘Oranea’ | Mollis | Galle85 | dec | |||
| ‘Orange Ball’ | Ilam | Galle85 | dec | |||
| ‘Orange Baron’ | Sonoma | Galle85 | evg | |||
| ‘Orange Beauty’ | Kaempferi | Galle85 | evg | |||
| ‘Orange Beauty’ | Wada/R. indicum | Galle87 | evg | Orange,White | ||
| ‘Orange Boven’ | Belgian Indian | Galle85 | evg | |||
| ‘Orange Cape’ | Girard | Galle87 | dec | Orange | ||
|
‘Orange Carpet’ | Sommerville | RareFind04 | dec | Orange | Early |
| ‘Orange Chimes’ | Belgian Indian | Galle85 | evg | |||
| ‘Orange Cloak’ | Girard | Galle87 | dec | Orange | ||
| Cultivar | Group | Ref | Type | Color | Bloom |