List Of Flower Names Beginning With O

Obedient Plant

Physostegia virginiana, or the obedient plant is a showy perennial which adds height and color into any garden.

Depending on the type chosen, and the growing conditions, the obedient plant can get to a maximum of 4 feet tall. 

Attracting plenty of beneficial insects including bees and butterflies, the obedient plant loves a warm, sunny position, in well-draining soil that gets a lot of moisture.

It’s hardy in USDA zones 3 through to 9.

Obovate Peony

Paeonia obovata, the obovate peony, is also known as the woodland peony. These herbaceous peonies grow anywhere from 30 to 70cm tall, featuring white, pink, or purple flowers.

Obovate peonies like partial shade in damp but well-draining soil,  where they will provide plenty of drama into any space.

Obovate peonies are hardy perennials in USDA zones 5 through to 8, and act as a magnet for bees and butterflies.


Orchid flowers are among the most distinct available. As the orchid family is the largest plant family in the world, there are many types to choose from, most of which love humid and warm environments in indirect light.

Orchids can flower in summer or winter, some flowers lasting for weeks at a time. Some orchids grow on bare rock, others grow on other plants and extract what they need from the air, and some orchids grow in soil.

Most orchids sold commercially are grown as houseplants, where they like the steady temperatures during the day, and the way light filters through windows, being much weaker than direct sunlight.

Ohio Spiderwort

Tradescantia ohiensis, bluejacket, or Ohio spiderwort, comes from eastern and central parts of North America. It has long, grass-like foliage, reaching 2 or 3 feet tall.

Vivid blue flowers open during the morning in late spring and early summer. Try not to touch them as the day warms up, though, as they will wilt!

These lovely perennials prefer partial shade, and dry soil. They’re easy to grow from seed, and make great additions to any garden.

Ohio spiderwort is loved by bees, and will grow as a perennial in USDA zones 4 through to 9.

Old Man of the Andes Flowers

Looking like an older relative of Cousin It, Oreocereus celsianus or the Old Man of the Andes is a cactus covered in gray hairs, which help shade the plant from the worst of the sun and its heat. 

Once the plant has matured, it flowers in fall, producing purple flowers, drawing in the bees. 

In the wild, the Old Man of the Andes can reach 10 feet tall. It needs a xeriscape landscape, which means that it gets more drought than rainfall.

The Old Man of the Ande’s native range is in the mountains of Peru, Bolivia, and Argentina, and it’s hardy in USDA zone 6 through to 10.

This unique cactus will thrive in USDA zones 8 through to 10, preferably in full sunlight, and freely draining soil. 

You can also grow it as a houseplant if you prefer, and if you do decide to grow it indoors, make sure you choose the brightest position possible, away from drafts.


Also known as nerium, oleander (see also Oleander Flower Symbolism) is a tropical flowering shrub which is grown all over the world. Its popularity is so widespread that no one is sure where it originates from.

Oleander comes from the dogbane family, Apocynaceae. This means that it is highly poisonous, so it’s not a good choice for gardens which have pets or children as frequent visitors.

Signs of poisoning include vomiting, drooling, stomach pain, and an irregular heart beat.

Oleanders can reach anywhere between 7 and 20 feet high, depending on the growing conditions and the variety selected.

Nerium can also be trained to grow as an ornamental tree if pruned from an early age (see also Nerium Grow Guide). 

It’s worth wearing gloves if you want to prune this plant, as it can cause skin irritation if you get the sap on your skin.

This plant is very robust, able to weather long dry spells and flooding without any problems, but one thing it cannot stand is long periods of freezing temperatures.

In summer, oleander really comes into its own, producing pink, red, or white flowers.  

These versatile shrubs are hardy in USDA zones 9 through to 11. 

Orange Coneflower

Rudbeckia fulgida, or the orange coneflower, is the perfect perennial to provide uplifting seas of orange and yellow flowers in summer.

This perennial plant is perfect for cut flower gardens, containers, and borders, where it will withstand drought.

Hailing from the eastern parts of North America, the orange coneflower is capable of reaching 120cm tall, and spreads well into any gaps in your garden, both by seed and runners. 

Orange coneflowers are helpful to have in any garden, not just for their ornamental value, but also to support wildlife.

The blooms provide food for pollinators, and if you leave the seed pods on, you’ll help provide food for finches in the winter.

The orange coneflower likes full sunlight and well-draining soil, like most rudbeckias. 

In zones 3 through to 9, orange coneflowers are perennials. In colder climates, you can grow them as summer bedding plants.

Orange Stonecrop

Sedum kamtschaticum, or  orange stonecrop is a mat-forming perennial which stays close to the ground, producing leathery green leaves (for gold foliage, choose a Golden Sedum) and bright yellowy orange flowers in summer.

It’s a perfect plant if you want a lot of color in well-draining soil sites such as rockeries or stony borders. 

Orange stonecrop gets between 15 and 20cm tall, spreading to a maximum of 60cm wide. 

It’s a happy plant in both full sunlight and partial shade, and stands up well against rabbits and deer. 

Once the stonecrop roots have settled into the soil, this plant will withstand dry spells with ease. 

Oriental Poppy

Papaver orientale, or the oriental poppy, is a lovely perennial which comes from parts of northern Iran and Turkey.

It’s grown across the world as a beautiful ornamental, producing huge leaves and bright flowers in spring, through to summer.

The oriental poppy will survive in a sunny position or in dappled shade, with well-draining soil. While these are robust plants, there are two things they cannot stand: too much water, and transplanting.

Once you’ve got your oriental poppies settled into the soil, resist the urge to move them.

If you cut off the spent flowers, you may see a second blooming period. 

Oriental poppies are hardy in zones 3 through to 9, and die back in as summer gets going, the plant going dormant during this period.

These plants require a neutral soil pH, between 6.5 and 7.0. If that’s not achievable, you can also grow these plants in pots.

Oriental poppies are toxic to both animals and humans.


Also known as the Cape Daisy, osteospermums are striking plants that produce plenty of long-lived, vivid blooms through summer. 

Treated as a colorful bedding plant in colder climates, the Cape daisy settles well both in containers and in borders.

They need full sunlight, in well-draining soil. If you live somewhere cold, you could grow these flowers in a container by the side of your house, to keep the worst of the wind and the cold away.

Osteospermums attract plenty of beneficial insects into the garden, and you can also take cuttings in spring or summer to spread them across your garden.

Ox Eye Daisy

Leucanthemum vulgare, or the ox eye daisy, comes from Europe and Asia, and this perennial is sure to provide a lot of cheer into any garden.

This plant gets to an average height of 60cm, making it a good option for beds and containers alike. 

Given time, the ox eye daisy will spread, with its creeping rhizome.

You can recognize an ox eye daisy by its hairy stems, toothed foliage, and white petals with a bright yellow eye.

In some places, the ox eye daisy is considered invasive, so check with your local authority to make sure it’s not on the list.

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