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

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

Aspect	Details
Botanical Name	Orchidaceae family
Common Name	Orchid
Plant Type	Perennial
Hardiness Zone	Varies widely (depends on species); often grown indoors
Sun Exposure	Indirect light to filtered sun
Soil Type	Epiphytic (air plants) or terrestrial (ground plants); specific to species
Watering Needs	Moderate; varies by species
Growth Habit	Varied; epiphytic orchids grow on other plants or surfaces, terrestrial orchids grow in soil
Height/Spread	Varies widely depending on species
Special Features	Highly 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

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

Aspect	Details
Botanical Name	Papaver orientale
Common Name	Oriental Poppy
Plant Type	Perennial
Hardiness Zone	Zones 3-7
Sun Exposure	Full sun
Soil Type	Well-drained, fertile soil
Watering Needs	Moderate
Growth Habit	Upright, clumping
Height/Spread	2-4 feet tall, 1-2 feet wide
Special Features	Large, 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

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

Aspect	Details
Botanical Name	Nerium oleander
Common Name	Oleander
Plant Type	Evergreen shrub or small tree
Hardiness Zone	Zones 8-11 (typically grown as a shrub; may not tolerate frost)
Sun Exposure	Full sun
Soil Type	Well-drained soil
Watering Needs	Low to moderate
Growth Habit	Upright, bushy
Height/Spread	6-12 feet tall, 4-8 feet wide
Special Features	Clusters 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

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

Aspect	Details
Botanical Name	Oxalis spp.
Common Name	Oxalis, Wood Sorrel
Plant Type	Perennial or annual
Hardiness Zone	Zones 6-11
Sun Exposure	Full sun to part shade
Soil Type	Well-drained, slightly acidic soil
Watering Needs	Moderate
Growth Habit	Low-growing, spreading
Height/Spread	4-12 inches tall, 6-12 inches wide
Special Features	Triangular 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

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

Aspect	Details
Botanical Name	Osteospermum spp.
Common Name	African Daisy, Cape Daisy
Plant Type	Perennial or annual
Hardiness Zone	Zones 9-11 (often grown as annuals elsewhere)
Sun Exposure	Full sun
Soil Type	Well-drained, sandy soil
Watering Needs	Moderate
Growth Habit	Low-growing, spreading
Height/Spread	6-12 inches tall, 12-24 inches wide
Special Features	Daisy-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

Here’s a chart with information about it:

Aspect	Details
Botanical Name	Physostegia virginiana
Common Name	Obedient Plant
Plant Type	Perennial
Hardiness Zone	Zones 3-9
Sun Exposure	Full sun to part shade
Soil Type	Moist, well-drained soil
Watering Needs	Moderate to high
Growth Habit	Upright, clumping
Height/Spread	2-4 feet tall, 1-2 feet wide
Special Features	Tubular, 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

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

Aspect	Details
Botanical Name	Oenothera spp.
Common Name	Evening Primrose
Plant Type	Biennial or perennial
Hardiness Zone	Zones 3-9
Sun Exposure	Full sun to part shade
Soil Type	Well-drained
Watering Needs	Moderate
Growth Habit	Upright
Height/Spread	1-5 feet tall, 1-2 feet wide
Special Features	Large, 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

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

Aspect	Details
Botanical Name	Citrus sinensis
Common Name	Orange Blossom
Plant Type	Evergreen tree
Hardiness Zone	Zones 9-11
Sun Exposure	Full sun
Soil Type	Well-drained, sandy loam
Watering Needs	Moderate
Growth Habit	Medium-sized tree
Height/Spread	20-30 feet tall, 15-25 feet wide
Special Features	Highly 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

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

Aspect	Details
Botanical Name	Ornithogalum spp.
Common Name	Star of Bethlehem
Plant Type	Bulbous perennial
Hardiness Zone	Zones 5-9
Sun Exposure	Full sun to part shade
Soil Type	Well-drained
Watering Needs	Moderate
Growth Habit	Upright, clumping
Height/Spread	6-18 inches tall, 6-12 inches wide
Special Features	Star-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

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

Aspect	Details
Botanical Name	Leucanthemum vulgare
Common Name	Oxeye Daisy
Plant Type	Perennial
Hardiness Zone	Zones 3-9
Sun Exposure	Full sun to part shade
Soil Type	Well-drained
Watering Needs	Low to moderate
Growth Habit	Upright, clumping
Height/Spread	1-3 feet tall, 1-2 feet wide
Special Features	Daisy-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

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

Aspect	Details
Botanical Name	Omphalodes spp.
Common Name	Navelwort
Plant Type	Perennial
Hardiness Zone	Zones 5-9
Sun Exposure	Part shade to full shade
Soil Type	Well-drained, moist
Watering Needs	Moderate
Growth Habit	Spreading, low-growing
Height/Spread	6-12 inches tall, 12-18 inches wide
Special Features	Small, 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

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

Aspect	Details
Botanical Name	Osteomeles anthyllidifolia
Common Name	Osteomeles
Plant Type	Evergreen shrub
Hardiness Zone	Zones 9-11
Sun Exposure	Full sun to part shade
Soil Type	Well-drained, fertile soil
Watering Needs	Moderate
Growth Habit	Upright, bushy
Height/Spread	4-6 feet tall, 4-6 feet wide
Special Features	Clusters 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

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

Aspect	Details
Botanical Name	Oncidium spp.
Common Name	Oncidium Orchid
Plant Type	Epiphytic or lithophytic orchid
Hardiness Zone	Zones 10-12
Sun Exposure	Bright, indirect light
Soil Type	Orchid bark mix or sphagnum moss
Watering Needs	Moderate; allow to dry slightly between waterings
Growth Habit	Clumping, pseudobulbs
Height/Spread	Varies widely; generally 1-3 feet tall
Special Features	Showy 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

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

Aspect	Details
Botanical Name	Ozothamnus spp.
Common Name	Ozothamnus
Plant Type	Evergreen shrub
Hardiness Zone	Zones 9-11
Sun Exposure	Full sun to part shade
Soil Type	Well-drained, sandy soil
Watering Needs	Low to moderate
Growth Habit	Upright
Height/Spread	3-6 feet tall, 2-4 feet wide
Special Features	Small, 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

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

Aspect	Details
Botanical Name	Orostachys iwarenge
Common Name	Chinese Dunce Cap
Plant Type	Perennial succulent
Hardiness Zone	Zones 5-9
Sun Exposure	Full sun to partial shade
Soil Type	Well-drained, sandy or rocky soil
Watering Needs	Low; drought-tolerant
Growth Habit	Rosette forming, ground cover
Height/Spread	2-6 inches tall / 6-12 inches spread
Special Features	Unique 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

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

Aspect	Details
Botanical Name	Allium spp.
Common Name	Ornamental Onion
Plant Type	Perennial bulb
Hardiness Zone	Zones 4-9
Sun Exposure	Full sun
Soil Type	Well-drained, sandy or loamy soil
Watering Needs	Moderate; drought-tolerant once established
Growth Habit	Upright, clumping
Height/Spread	12-48 inches tall / 6-12 inches spread (varies by species)
Special Features	Globular 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

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

Aspect	Details
Botanical Name	Monarda didyma
Common Name	Oswego Tea, Bee Balm
Plant Type	Perennial herb
Hardiness Zone	Zones 4-9
Sun Exposure	Full sun to partial shade
Soil Type	Moist, well-drained soil
Watering Needs	Regular; keep soil consistently moist
Growth Habit	Upright, clumping
Height/Spread	2-4 feet tall / 1.5-3 feet spread
Special Features	Showy, 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

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

Aspect	Details
Botanical Name	Tacca chantrieri
Common Name	Black Bat Flower, Bat Flower, Oyster Flower
Plant Type	Perennial herb
Hardiness Zone	Zones 9-11
Sun Exposure	Partial shade to full shade
Soil Type	Well-drained, rich, and moist soil
Watering Needs	Regular; keep soil consistently moist but not waterlogged
Growth Habit	Upright, clumping
Height/Spread	2-3 feet tall / 1-2 feet spread
Special Features	Unique 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

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

Aspect	Details
Botanical Name	Olearia spp.
Common Name	Daisy Bush, Olearia
Plant Type	Evergreen shrub
Hardiness Zone	Zones 8-10
Sun Exposure	Full sun to partial shade
Soil Type	Well-drained soil
Watering Needs	Moderate; drought-tolerant once established
Growth Habit	Upright, bushy
Height/Spread	3-10 feet tall / 3-6 feet spread (varies by species)
Special Features	Daisy-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!