Growing Pregnant Onion: How To Care For Ornithogalum Caudatum

Although the Ornithogalum caudatum [or-ni-THOG-al-um] [kaw-DAY-tum] is often called a Pregnant onion plant, it is not an onion. Instead, it’s part of the Liliaceae family.

It’s referred to as a Pregnant onion plant because of its onion-like rootstalk from which new growth emerges.

Growing Ornithogalum CaudatumPin

Long green leaves grow from the bulbous rootball. Small white flowers bloom on 5″ inches-tall stems in the spring and summer.

Synonyms for this plant are the following:

  • Eliokarmos caudatum
  • Loncomelos caudatum
  • Urophyllon caudatum

The plant is from South Africa’s subtropical regions. The plant thrives in the forest, natural shrubland, and grassy plains.

Forests, forest borders, dense woodland, and sheltering rock ledges are good places to find this bulb in the wild.

Ornithogalum can be planted indoors or out, making it an easy plant for beginners.

In addition, some gardeners will argue that growing a Pregnant onion plant is foolproof.

However, despite the ease of growing and maintenance, the plant is poisonous, and even the sap may cause skin rashes.

Some of the Ornithogalum common names are:

  • Pregnant onion plant
  • False onion
  • False sea onion
  • Sea onion
  • Sea Squill
  • Long-spiked Star of Bethlehem

Quick Facts On Ornithogalum Caudatum

  • Family: Liliaceae
  • Light: Full sun to shade
  • Temperature: Moderate; hardiness zones 4-10
  • Water: Drought tolerant; Let the soil dry out between waterings 
  • Fertilizer: Liquid fertilizer during spring and summer
  • Propagation: Bulblets, seeds
  • Common Problems: Mealybugs, bulb rot

Ornithogalum Caudatum Care

What Does The Pregnant Onion Plant Look Like, And How Big Does It Grow?

The long bright green leaves grow out of a bulbous onion-like rootstalk called a caudex. The caudex rests on top of the soil.

Large spines grow out of the rootstalk with small white flowers on top. Flowering usually occurs in late spring or summer.

While the flowers are pretty, they are not as beautiful as other Ornithogalum.

The Ornithogalum caudatum grows up to 3′ tall and only 2′ wide. It’s easy to maintain this size when kept indoors as a potted plant.

Unlike many other plants in this genus, the Pregnant Onion doesn’t have a dormant period and is evergreen all year long.

When Does Pregnant Onion Plant Flower? Are The Flowers Fragrant?

The Ornithogalum blooms in late spring or summer. Small white-green flowers form on the top of large spikes and are slightly fragrant.

The Pregnant onion can have 200 blooms at any given time during the flowering season.

While this plant’s blooms are pretty, they are not as beautiful as other Ornithogalum plants, such as the Ornithogalum nutans, known as the Star of Bethlehem.

What Are The Lighting Needs And Temperature Requirements?

The Pregnant onion can be grown indoors or outdoors with the proper temperatures and light.

If you live in hardiness zones 4 to 10, you can plant your pregnant onion indoors or out. 

Caudatum thrives in temperatures between 60° to 80° degrees Fahrenheit, making it an ideal houseplant.

However, if you live in a climate with cold winters, you can keep it potted outside and bring the plant in during the winter weather.

Since the Ornithogalum is a subtropical plant, it is happiest with at least four hours of bright sun.

Therefore, if planted inside, you want to ensure that it gets the proper sunlight from the window.

If outdoors, it thrives in full sun during the spring and the fall, but when temperatures rise, it prefers part shade.

Although caudatum enjoys sun, you will know if it has had too much sun because it will develop orange sunburned patches on its leaves.

If this happens, move it to a spot with a little less direct sun. This should fix the problem.

How And When To Water And Fertilize Pregnant Onion Plant?

Like many subtropical plants, Ornithogalum caudatum is happiest with consistent watering, but it’s best to ensure that the soil is dry between waterings.

Although the plant is technically drought tolerant, it does better overall with water.

There is no need to keep watering in the winter.

The Pregnant onion prefers a diluted liquid fertilizer applied monthly during the spring, summer, and fall.

However, the plant does not need fertilizer in the winter.

What Is The Best Soil For Ornithogalum And When Should You Transplant?

While some gardeners might say that the Ornithogalum caudatum doesn’t have special soil needs, well-draining soil is recommended.

Although it will likely grow in whatever soil you put in your container or pot, it will prosper with better soil.

A potting mix with added perlite is an excellent option.

Repotting your plant isn’t necessary unless it’s outgrowing its current pot. If so, it’s best to gently transplant the caudatum into a new pot in the springtime.

Does Ornithogalum Need Special Grooming Or Maintenance?

Ornithogalums do not need any special grooming, which is one of the many reasons gardeners find this plant irresistibly easy.

The only minor task you can do is remove the dried peels from the onion-like bulbs. This will encourage continued growth.

As long as your Ornithogalum caudatum plant has sufficient water and sunlight, it will be happy.

How To Propagate False Sea Onion?

False sea Onions are so easy to propagate, which is why the plant is so popular.

Also called a Pregnant onion, the Sea Onion grows lumps on its bulb. These lumps grow larger until a baby bulb is hidden under the outer skin.

Eventually, the outer skin falls off, and the bulblets fall into the soil.

Now, move the little bulblets into their own small pots with well-draining soil.

With the right light and water, they will grow to be mature Ornithogalum caudatum plants.

Pregnant Onion Pests And Diseases

Gardeners find the Pregnant onion one of the best plants to grow for beginners because it’s low maintenance and because the plant somehow resists most pests and diseases.

If the plant is overwatered, it will potentially get bulb rot. However, if the plant is in all of the proper conditions, the likelihood of it getting pest infestations is pretty low.

If mealybugs become a problem, you can actually wipe them off the leaves with a wet paper towel. If that doesn’t work, neem oil is the second-best option.

False Onion Uses

The Ornithogalum caudatum, or False Onion plant, needs very little care as a houseplant.

However, if you prefer the False Onion to live outdoors, you can plant it in rock, succulent, and flower gardens.

It’s a unique evergreen plant with semi-fragrant blooms that propagates easily and requires little maintenance.

The False onion grows in forests, woodlands, and rock ledges in the wild.

Wherever you keep your False Onion, you will benefit from its unique beauty.