Outstanding Flowers That Start with O

Discover 19 outstanding flowers that start with O! From Orchids to Oriental Poppies, learn their unique traits and how to grow them beautifully in your garden.

Flowers make our gardens beautiful. Some flowers have names that start with the letter O. Let’s learn about 19 of these special flowers and how to grow them.

1. Orchid

White and purple orchids in full bloom.

Here’s a chart with information about the Orchid flower:

AspectDetails
Botanical NameOrchidaceae family
Common NameOrchid
Plant TypePerennial
Hardiness ZoneVaries widely (depends on species); often grown indoors
Sun ExposureIndirect light to filtered sun
Soil TypeEpiphytic (air plants) or terrestrial (ground plants); specific to species
Watering NeedsModerate; varies by species
Growth HabitVaried; epiphytic orchids grow on other plants or surfaces, terrestrial orchids grow in soil
Height/SpreadVaries widely depending on species
Special FeaturesHighly diverse flowers in terms of shape, size, and color; blooms throughout the year depending on species; known for complex pollination mechanisms; popular as indoor plants due to their exotic appearance

Orchids are beautiful flowers that come in many colors. They can be hard to grow but look amazing. Some orchids grow on trees, while others grow in the ground.

2. Oriental Poppy

Orange Oriental Poppy flower with raindrops on petals.

Here’s a chart with information about the Oriental Poppy flower:

AspectDetails
Botanical NamePapaver orientale
Common NameOriental Poppy
Plant TypePerennial
Hardiness ZoneZones 3-7
Sun ExposureFull sun
Soil TypeWell-drained, fertile soil
Watering NeedsModerate
Growth HabitUpright, clumping
Height/Spread2-4 feet tall, 1-2 feet wide
Special FeaturesLarge, silky, cup-shaped flowers in shades of red, orange, pink, or white; blooms in late spring to early summer; attractive to bees; deer-resistant; may go dormant in summer

Oriental Poppies have big, bright flowers. They are usually orange or red. These flowers like full sun and bloom in early summer.

3. Oleander

Pink Oleander flowers blooming in a garden near a balcony.

Here’s a chart with information about the Oleander flower:

AspectDetails
Botanical NameNerium oleander
Common NameOleander
Plant TypeEvergreen shrub or small tree
Hardiness ZoneZones 8-11 (typically grown as a shrub; may not tolerate frost)
Sun ExposureFull sun
Soil TypeWell-drained soil
Watering NeedsLow to moderate
Growth HabitUpright, bushy
Height/Spread6-12 feet tall, 4-8 feet wide
Special FeaturesClusters of fragrant, funnel-shaped flowers in shades of white, pink, red, or yellow; glossy green leaves; drought-tolerant once established; toxic if ingested

Oleander is a bush with pretty flowers. It can be pink, red, or white. Be careful, because oleander is poisonous if eaten.

4. Oxalis

White Oxalis flower with green center in blue pot.

Here’s a chart with information about the Oxalis flower:

AspectDetails
Botanical NameOxalis spp.
Common NameOxalis, Wood Sorrel
Plant TypePerennial or annual
Hardiness ZoneZones 6-11
Sun ExposureFull sun to part shade
Soil TypeWell-drained, slightly acidic soil
Watering NeedsModerate
Growth HabitLow-growing, spreading
Height/Spread4-12 inches tall, 6-12 inches wide
Special FeaturesTriangular leaves that fold at night or in shade; flowers in shades of white, pink, yellow, or purple; blooms spring to fall; can be invasive; some species are edible

Oxalis is also called Wood Sorrel. It has small flowers and leaves that look like clovers. Some types of Oxalis are good garden plants, while others can be weeds.

5. Osteospermum

Purple Osteospermum daisy flowers with green leaves and purple petals.

Here’s a chart with information about the Osteospermum flower:

AspectDetails
Botanical NameOsteospermum spp.
Common NameAfrican Daisy, Cape Daisy
Plant TypePerennial or annual
Hardiness ZoneZones 9-11 (often grown as annuals elsewhere)
Sun ExposureFull sun
Soil TypeWell-drained, sandy soil
Watering NeedsModerate
Growth HabitLow-growing, spreading
Height/Spread6-12 inches tall, 12-24 inches wide
Special FeaturesDaisy-like flowers in shades of purple, pink, white, or orange; blooms spring to fall; drought-tolerant; attracts butterflies; suitable for borders, containers, and rock gardens

Osteospermum is also called African Daisy. It has flowers that look like daisies in many colors. These plants like full sun and are good for gardens in warm places.

6. Obedient

Purple Obedient Plant flowers surrounded by green foliage in a garden.

Here’s a chart with information about it:

AspectDetails
Botanical NamePhysostegia virginiana
Common NameObedient Plant
Plant TypePerennial
Hardiness ZoneZones 3-9
Sun ExposureFull sun to part shade
Soil TypeMoist, well-drained soil
Watering NeedsModerate to high
Growth HabitUpright, clumping
Height/Spread2-4 feet tall, 1-2 feet wide
Special FeaturesTubular, snapdragon-like flowers that can be moved and will stay in position for a time after being pushed into different positions; blooms in summer; attracts bees and butterflies; deer-resistant

The Obedient Plant got its name because you can move its flowers, and they stay in place. It has pink or white flowers on tall stems.

7. Oenothera

yellow Evening Primrose flower with glistening water droplets.

Here’s a chart with information about the Evening Primrose flower:

AspectDetails
Botanical NameOenothera spp.
Common NameEvening Primrose
Plant TypeBiennial or perennial
Hardiness ZoneZones 3-9
Sun ExposureFull sun to part shade
Soil TypeWell-drained
Watering NeedsModerate
Growth HabitUpright
Height/Spread1-5 feet tall, 1-2 feet wide
Special FeaturesLarge, fragrant flowers that open in the evening and last through the night; blooms in late spring to summer; attracts pollinators like moths; used in herbal medicine for its oil-rich seeds

Oenothera flowers open in the evening. They are usually yellow and smell nice. These plants are easy to grow and like sunny spots.

8. Orange Blossom

Butterfly perched on Orange Blossom flower.

Here’s a chart with information about the Orange Blossom flower:

AspectDetails
Botanical NameCitrus sinensis
Common NameOrange Blossom
Plant TypeEvergreen tree
Hardiness ZoneZones 9-11
Sun ExposureFull sun
Soil TypeWell-drained, sandy loam
Watering NeedsModerate
Growth HabitMedium-sized tree
Height/Spread20-30 feet tall, 15-25 feet wide
Special FeaturesHighly fragrant white flowers with five petals; blooms in spring; attracts bees; produces oranges; symbolic in various cultures for purity, fertility, and good fortune

Orange Blossoms are the flowers of orange trees. They are white and smell very sweet. These flowers are used to make perfume.

9. Ornithogalum

Elegant white blooms of Ornithogalum surrounded by green leaves.

Here’s a chart with information about the Star of Bethlehem flower:

AspectDetails
Botanical NameOrnithogalum spp.
Common NameStar of Bethlehem
Plant TypeBulbous perennial
Hardiness ZoneZones 5-9
Sun ExposureFull sun to part shade
Soil TypeWell-drained
Watering NeedsModerate
Growth HabitUpright, clumping
Height/Spread6-18 inches tall, 6-12 inches wide
Special FeaturesStar-shaped, white flowers arranged in clusters; blooms in spring; attracts bees; can be invasive in some regions; often used in floral arrangements and naturalizing landscapes

Ornithogalum has star-shaped white flowers. It grows from bulbs and can spread quickly. Some people think it’s pretty, while others see it as a weed.

10. Oxeye Daisy

Close-up image of a white Oxeye Daisy showing off its vibrant yellow center.

Here’s a chart with information about the Oxeye Daisy flower:

AspectDetails
Botanical NameLeucanthemum vulgare
Common NameOxeye Daisy
Plant TypePerennial
Hardiness ZoneZones 3-9
Sun ExposureFull sun to part shade
Soil TypeWell-drained
Watering NeedsLow to moderate
Growth HabitUpright, clumping
Height/Spread1-3 feet tall, 1-2 feet wide
Special FeaturesDaisy-like flowers with white petals and yellow centers; blooms in late spring to summer; attracts butterflies and bees; deer-resistant; good for naturalizing in meadows and cottage gardens

Oxeye Daisies look like big white daisies with yellow centers. They are easy to grow and can spread fast. Some places see them as wildflowers, while others think they’re weeds.

11. Omphalodes

Delicate Omphalodes flowers, commonly known as Forget-Me-Nots, in bloom.

Here’s a chart with information about the Omphalodes (Navelwort) flower:

AspectDetails
Botanical NameOmphalodes spp.
Common NameNavelwort
Plant TypePerennial
Hardiness ZoneZones 5-9
Sun ExposurePart shade to full shade
Soil TypeWell-drained, moist
Watering NeedsModerate
Growth HabitSpreading, low-growing
Height/Spread6-12 inches tall, 12-18 inches wide
Special FeaturesSmall, forget-me-not-like flowers in shades of blue or white; blooms in spring to early summer; attracts pollinators; suitable for woodland gardens, borders, and rock gardens

Omphalodes has small blue flowers that look like forget-me-nots. It likes shady spots and is good for ground cover.

12. Osteomeles

White Osteomeles flower on tree branch.

Here’s a chart with information about the Osteomeles flower:

AspectDetails
Botanical NameOsteomeles anthyllidifolia
Common NameOsteomeles
Plant TypeEvergreen shrub
Hardiness ZoneZones 9-11
Sun ExposureFull sun to part shade
Soil TypeWell-drained, fertile soil
Watering NeedsModerate
Growth HabitUpright, bushy
Height/Spread4-6 feet tall, 4-6 feet wide
Special FeaturesClusters of small white flowers; glossy green leaves; drought-tolerant once established; attracts birds; suitable for hedges and landscaping

Osteomeles is a bush with small white flowers and red berries. It’s often used for bonsai because it has small leaves.

13. Oncidium Orchid

Yellow Oncidium Orchid plant in greenhouse.

Here’s a chart with information about the Oncidium Orchid flower:

AspectDetails
Botanical NameOncidium spp.
Common NameOncidium Orchid
Plant TypeEpiphytic or lithophytic orchid
Hardiness ZoneZones 10-12
Sun ExposureBright, indirect light
Soil TypeOrchid bark mix or sphagnum moss
Watering NeedsModerate; allow to dry slightly between waterings
Growth HabitClumping, pseudobulbs
Height/SpreadVaries widely; generally 1-3 feet tall
Special FeaturesShowy sprays of flowers with intricate patterns and bright colors (yellow, orange, red, brown); blooms last several weeks to months; popular for indoor cultivation; requires high humidity and good air circulation

Oncidium Orchids are also called Dancing Lady Orchids. They have many small flowers that look like dancing ladies.

14. Ozothamnus

White Ozothamnus flowers blooming on a bush with lush green leaves.

Here’s a chart with information about the Ozothamnus flower:

AspectDetails
Botanical NameOzothamnus spp.
Common NameOzothamnus
Plant TypeEvergreen shrub
Hardiness ZoneZones 9-11
Sun ExposureFull sun to part shade
Soil TypeWell-drained, sandy soil
Watering NeedsLow to moderate
Growth HabitUpright
Height/Spread3-6 feet tall, 2-4 feet wide
Special FeaturesSmall, white or pink flowers in clusters; aromatic foliage; drought-tolerant once established; attracts bees and butterflies; suitable for coastal gardens and native plant landscapes

Ozothamnus is a bush with lots of tiny white flowers. It’s also called Rice Flower. The flowers are good for dried arrangements.

15. Orostach

Orostach plant showcasing beautiful white flowers up close.

Certainly! Here’s a formatted chart with information about the Orostachys flower:

AspectDetails
Botanical NameOrostachys iwarenge
Common NameChinese Dunce Cap
Plant TypePerennial succulent
Hardiness ZoneZones 5-9
Sun ExposureFull sun to partial shade
Soil TypeWell-drained, sandy or rocky soil
Watering NeedsLow; drought-tolerant
Growth HabitRosette forming, ground cover
Height/Spread2-6 inches tall / 6-12 inches spread
Special FeaturesUnique rosette shape, attractive during winter, low maintenance

Orostachys is a succulent plant with small flowers. It looks like a green rose before it blooms. This plant is good for rock gardens.

16. Ornamental Onion

A close-up of a purple allium flower with green stems, also known as Ornamental Onion.

Certainly! Here’s a formatted chart with information about the Ornamental Onion flower:

AspectDetails
Botanical NameAllium spp.
Common NameOrnamental Onion
Plant TypePerennial bulb
Hardiness ZoneZones 4-9
Sun ExposureFull sun
Soil TypeWell-drained, sandy or loamy soil
Watering NeedsModerate; drought-tolerant once established
Growth HabitUpright, clumping
Height/Spread12-48 inches tall / 6-12 inches spread (varies by species)
Special FeaturesGlobular flower heads, attracts pollinators, deer and rabbit resistant, long-lasting blooms

Ornamental Onions have round flower heads made up of many small flowers. They come in purple, pink, or white. These plants are related to the onions we eat.

17. Oswego Tea

 A pink Oswego Tea flower with green leaves in the background.

Certainly! Here’s a formatted chart with information about the Oswego Tea flower:

AspectDetails
Botanical NameMonarda didyma
Common NameOswego Tea, Bee Balm
Plant TypePerennial herb
Hardiness ZoneZones 4-9
Sun ExposureFull sun to partial shade
Soil TypeMoist, well-drained soil
Watering NeedsRegular; keep soil consistently moist
Growth HabitUpright, clumping
Height/Spread2-4 feet tall / 1.5-3 feet spread
Special FeaturesShowy, aromatic flowers, attracts bees, butterflies, and hummingbirds, medicinal uses, deer resistant

Oswego Tea is also called Bee Balm. It has red, pink, or purple flowers that look like spiky balls. This plant attracts bees and butterflies.

18. Oyster

Purple and white petals of an Oyster flower.

Certainly! Here’s a formatted chart with information about the Oyster flower:

AspectDetails
Botanical NameTacca chantrieri
Common NameBlack Bat Flower, Bat Flower, Oyster Flower
Plant TypePerennial herb
Hardiness ZoneZones 9-11
Sun ExposurePartial shade to full shade
Soil TypeWell-drained, rich, and moist soil
Watering NeedsRegular; keep soil consistently moist but not waterlogged
Growth HabitUpright, clumping
Height/Spread2-3 feet tall / 1-2 feet spread
Special FeaturesUnique bat-shaped flowers with long whiskers, attracts attention, exotic appearance, prefers humid environments

The Oyster Plant is also called Boat Lily. It has small white flowers and leaves that are purple underneath. This plant is good for indoor gardens.

19. Olearia

White Olearia flower with yellow centers in a pot.

Certainly! Here’s a formatted chart with information about the Olearia flower:

AspectDetails
Botanical NameOlearia spp.
Common NameDaisy Bush, Olearia
Plant TypeEvergreen shrub
Hardiness ZoneZones 8-10
Sun ExposureFull sun to partial shade
Soil TypeWell-drained soil
Watering NeedsModerate; drought-tolerant once established
Growth HabitUpright, bushy
Height/Spread3-10 feet tall / 3-6 feet spread (varies by species)
Special FeaturesDaisy-like flowers, fragrant foliage, attracts pollinators, salt-tolerant, low maintenance

Olearia is called the New Zealand Daisy Bush. It has lots of small daisy-like flowers. This plant is good for coastal gardens because it can handle salty air.

These 19 flowers that start with O can make your garden special. Remember to check what grows best in your area before you plant. Happy gardening!

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