How to Plant, Grow, and Care for Climbing Onion Plants


Climbing onion (Bowiea volubilis), also sometimes called Zulu potato or Bowiea sea onion, is an easy-to-grow and very unusual-looking houseplant. Despite being a member of the Asparagus family and having common names that liken it to onions and potatoes, no part of the plant is edible.

Climbing onion plants are interesting, low-maintenance houseplants. They resemble a tangle of leafless, delicate, green stems with frilly-looking tendrils emerging from a large, round, bulb-like base. When they go dormant, you are left with a fleshy, green, bulb-like base that rests quietly before awakening with fresh green growth.

All you need to grow one is a bright window, warm temperatures, a pot with good drainage, well-drained soil, and a little bit of regular watering. Once your plant is set up in a good location, it should be quite trouble-free, and you can enjoy it for many years to come. 

If you’re looking for a low-fuss but high-interest plant to grow at home, consider adding a climbing onion to your houseplant collection. Let’s now dig in to learn more about their care and maintenance.

Plant Overview

Close-up of several Bowiea volubilis plants in a large black pot with decorative pebbles on the soil. Its bulbs, which serve as the base for its growth, are smooth, round, and resemble small onions. The bulbs vary in size and are pale green to brown in color. The plant's slender, twining stems bear long, narrow, and fleshy leaves that emerge from the bulbs.


Plant Type


Houseplant, tender perennial


USDA Hardiness Zone


10 – 11


Sun Exposure


Full sun to partial shade


Soil Type


Gritty, well-drained


Watering Requirements


Low


Maintenance


Division, pruning


Suggested Uses


Houseplant, containers


Bloom Season


Winter, spring


Resistant To


Drought, heat


Plant Spacing


4 – 6 inches

Plant Natural History

Close-up of growing Bowiea volubilis bulbs among succulents in a garden. The plant has large, round, slightly flattened greenish-brown bulbs. Young shoots grow from the centers of the bulbs. Echeveria elegans is a stunning succulent with a distinctive rosette form. The plant is characterized by its tightly packed, fleshy, pale blue-green leaves that form a perfect, symmetrical rosette shape. The leaves have a powdery coating.
Climbing onions thrive in warm, arid conditions.

Fascinating climbing onion plants are native to eastern and southern Africa’s warm, dry climates. They flourish in exposed, sunny, desert-like environments. In their natural habitat, they grow on dry, rocky hillsides, often in loose, gravelly soil.

This is a tender perennial. Depending on whether you are growing indoors or outdoors, the light and climate conditions affect the timing of lengths of dormancy. Regardless of exactly when it happens, these plants typically go dormant for a couple of months, so don’t worry if your onion vines wither and turn brown. As long as the bulb is thick and healthy-looking, it’s just saving its energy for its next growth spurt!

Despite its name, this plant is not an onion, nor is it edible. Do not try to eat it. Climbing onion is, in fact, slightly toxic and can cause mild digestive distress if any part of the plant is consumed. Do not allow your indoor pets to consume this plant, either.

Characteristics

A closeup view of Bowiea volubilis leaves reveals a unique and intricate structure. The leaves of Bowiea volubilis are slender and strap-like, featuring a glossy, deep green color.
Vining stems grow rapidly without tendrils, forming a lacy tangle around support structures.

At the beginning of their active growing season, thin, bright green vining stems emerge from the center of each bulb. Each bulb may produce a single stem, or sometimes two or three stems will sprout from a single little hole at the center of the same bulb. 

The leafless stems are uniformly green and fast-growing. They loosely grow up any nearby support. As the stems lengthen and mature, side shoots develop, creating a lacy tangle of thin, delicate vegetation. Unlike many other climbing vines, however, the climbing onion does not produce twining tendrils. Instead, the vines simply entangle themselves in and around any nearby structure, occasionally gently twisting around an available holding site.

Sometime during the peak of its active growth phase, you may notice tiny, star-shaped flowers that appear singly along the stems. The flowers are almost exactly the same shade of green as the stems, making them a bit difficult to see unless you look very closely.

There is a large succulent bulb at the base of each plant. In ideal, natural conditions, this bulb can grow 15 to 20 cm across. In the home environment, bulbs are unlikely to grow more than five to 10 cm across. This bulb sits at the soil surface and makes a large, rounded, light-green, smooth mass. Older bulbs develop a thin, papery coating that resembles the skin of an onion. 

Propagation

The easiest way to propagate is by division of bulbs. It is very rare for a climbing onion to produce seeds, but if it does, new plants can be started from these seeds.

Seed

Close-up of a farmer sowing seeds in small containers with fertile soil on a blurred green background. Plastic black seed trays are filled with soil mixture. A gardener in a pink T-shirt takes seeds from a small blue bowl.
Grow from seeds by covering the surface with a thin layer of sand and keeping them moist.

If you acquire seeds from a climbing onion plant, go ahead and try to grow them! This could be a fun project, and it would be interesting to watch one of these plants develop from a tiny seed.

Place your seeds on the surface of loose, well-drained soil and cover them with a very thin layer of sand, vermiculite, or perlite. Keep the soil surface moist until the seeds germinate and start to develop bulbs.

Division

Close-up of Bowiea volubilis in a black plastic pot indoors. The plant features intricate, coiling stems that give it a distinct, vine-like appearance. The wiry stems are adorned with delicate, spherical bulbs and slender, strap-like leaves. The bulbs are characterized by a papery outer layer that varies in color, adding texture and visual interest.
Separate bulbs during dormancy by gently dividing and replanting them individually.

Every few years, a healthy climbing onion will produce bulb offsets. These will then grow and mature alongside the parent bulb. You do not need to divide bulbs from each other unless the pot is getting too crowded or unless you want to propagate your plants. During any time of dormancy, separate the bulbs from each other and repot them in separate pots with fresh potting soil. 

To divide the bulbs, loosen the soil and remove the entire plant mass from the pot. Using your hands, gently separate the bulbs from each other. They should separate easily. Each bulb will have its own set of roots on the underside, so try to keep the roots intact on each one. Prepare pots and soil as described below and carefully replant each bulb in a fresh, clean pot with fresh soil.

Transplanting

Top view, close-up view of a Bowiea volubilis bulbs in a black pot on a terrace. The bulbs are round in shape, green-brown in color. Vertical green slender stems grow from the centers of the bulbs.
Choose a well-draining pot slightly wider than the bulb and use cactus or succulent soil.

One of the most important things to know when transplanting a climbing onion is to choose a pot with a drainage hole. It needs freely-draining soil, and the soil can’t do that without substantial holes in the bottom of the pot. Ceramic pots with drainage holes in the bottom are best because they are highly breathable. 

Pot size is important with these plants. They prefer to grow in somewhat snug conditions. You can create ideal conditions by keeping them in a pot just a little wider than the bulb itself. Don’t worry about your onion outgrowing its pot too soon. They grow slowly. 

The other item you will need, along with a well-draining pot, is loose soil. A soil blend designed for cacti and succulents is a great option. If you want to create your own soil mixture, combine an approximately 50/50 blend of houseplant potting soil and sand. Mix these two together thoroughly and use this as your potting soil. 

How to Grow

These houseplants are very easy to grow. They need sunlight, warmth, and enough water to occasionally moisten the soil. 

Sunlight

Close-up of a climbing onion (Bowiea volubilis) in a black pot in the urban garden. The plants have several bulbs from the centers of which vining and twining stems grow. The bulbs are medium in size, round in shape, green in color with a brownish papery outer layer. The plant's leaves are slender, strap-like, and have a glossy green hue.
Provide full sun to partial shade for optimal growth.

Your climbing onion needs full sun to partial shade. They also perform well indoors when grown under a full-spectrum grow light. If you grow them in a large window with direct sun exposure, move them back if you notice burns on the foliage. However, any bright window should provide plenty of sunlight. 

Water

Close-up of Bowiea volubilis in a large clay pot. The small, spherical bulbs exhibit a textured, papery outer layer, displaying a range of earthy tones from pale brown to reddish-brown. The slender, strap-like leaves emerge gracefully from the bulbs, showing a glossy green surface.
Let the soil dry between waterings, then water and remove excess.

Allow the soil to dry thoroughly between waterings. After the soil has dried, give the pot a thorough watering. Then, allow the soil to dry again. After the extra water has drained out the bottom of the pot, remove the extra so the pot does not continue to stand in water.

Soil

Close-up of female hands in white and green gloves pouring fresh soil into a flower pot on a table covered with craft paper. The pot is medium size, clay. The soil is loose and brown.
Opt for loose, sandy, well-drained cactus soil.

The soil you use should be loose, sandy, and well-drained. Use cactus and succulent soil. These plants are best adapted to grow in somewhat nutrient-poor soil and do not require organic, high-nutrient soil. You don’t need to use a very deep pot either, as these plants have shallow root systems.

Climate and temperature

Top view of a Bowiea volubilis in a black plastic pot. The soil is covered with a layer of small decorative brown pebbles. The plant has rounded green-brown bulbs from the centers of which thin green stems grow. This succulent features wiry, twining stems with glossy, strap-like leaves of bright green.
Climbing onion thrives in warm climates, tolerating temperatures between 40-50°F (4-10°C) and varied humidity levels.

Climbing onion is adapted to a warm climate. The minimum temperature these plants should be exposed to is 40 to 50 degrees Fahrenheit (4 to 10 degrees Celsius). These plants tolerate both high and low humidity. 

If you want to, move your potted plant outside for the summer. This would be ideal if you have a sheltered location that receives some bright light during the day. You don’t want to place it in full, direct sunlight outdoors, as this is a bit too intense for a plant used to the indoors. A shaded porch is a good choice. Bring your plant in if the temperature drops below 50 degrees Fahrenheit (10 degrees Celsius).

Fertilizing

Close-up of Bowiea volubilis bulbs in a garden bed with climbing stems. The plant's leaves are slender, strap-like, and glossy green, emerging gracefully from the central stem. The leaves often cascade and arch, emphasizing the climbing nature of Bowiea volubilis. The bulbs are of different sizes, round in shape, green in color with a brownish outer layer.
Feed lightly during active growth, avoiding dormancy periods.

Climbing onions are well adapted to nutrient-poor soil and do not require supplemental feeding. A typical well-drained houseplant soil mixture should provide sufficient nutrients for your plant.

If you feel that you must fertilize, do so very lightly and only during periods of active growth. Do not fertilize when your plant shows signs of dormancy and is not actively growing.

Maintenance

Close-up of climbing onion bulbs in a large black plastic pot. These bulbs are small, spherical structures that feature a papery outer layer, displaying a spectrum of colors from pale brown to reddish-brown. These bulbs serve as the foundation for the succulent's graceful foliage.
Allow bulb offsets to grow in a clump, and divide them if the pot becomes overcrowded.

If your climbing onion has reproduced and created bulb offsets, you can allow them to continue growing in a clump. If your clump gets too big for the pot, however, you eventually want to divide it to make sure the pot does not become overcrowded

The other regular maintenance is pruning. Once the plant goes dormant and the stems wither, turn brown, and die back, prune them off. Use sharp pruning snips or clean, sharp scissors and trim off the spent stems near the base, just above the bulb. 

These plants like to climb, but they will also trail along. You can add a small structure to your pot for your onion to climb along. You can also allow it to trail over the edge of the pot and sprawl along beside its pot.

Another option is to grow them in a hanging basket. Some stems will probably climb up the supports for the hanging basket, while other stems will trail over the edge for a graceful green display.

Varieties

There is one species of climbing onion, Bowiea volubilis, and within this species, there are two very similar subspecies. The primary species, Bowiea volubilis, is the species most commonly encountered as a houseplant. They each have very similar characteristics and growing requirements.

Bowiea volubilis ssp. gariepensis 

Close-up of a flowering plant, Bowiea volubilis ssp. gariepensis in a sunny garden. The slender, strap-like leaves are glossy green, emerging gracefully from the central stem and creating an elegant and symmetrical arrangement. The plant produces tall and slender flower stalks topped with clusters of small, star-shaped flowers. These flowers are small and creamy white in color.
The Southern African Bowiea features shorter, thicker stems and small, white, six-petaled flowers.

This species of Bowiea comes from southern Africa. It has slightly shorter and thicker stems with tiny, white, six-petaled flowers.

Bowiea volubilis ssp. volubilis

Close-up of a flowering plant, Bowiea volubilis ssp. volubilis on a black background. The plant's leaves are slender, strap-like, and glossy green, arranged in an attractive and symmetrical manner along the vining stems. the plant produces tall, wiry stalks topped with clusters of small, star-shaped flowers of pale green color.
This Bowiea subspecies showcases long, thin, branching stems with subtle green, star-shaped flowers.

This subspecies has long, thin, many-branching stems with inconspicuous star-shaped green flowers. It is also from South Africa.

Common Problems

Close-up of rotting bulbs of a Bowiea volubilis plant in a pot. Encased in a papery outer layer, the bulbs vary in color from pale brown to reddish-brown. The bulb itself is pale green. One bulb has a rotting part.
Maintain a thriving climbing onion houseplant by avoiding cold exposure and overwatering, preventing root rot.

Climbing onion plants are generally trouble-free. As long as you don’t let your plant get too cold or too wet, you should be able to maintain a thriving houseplant for a very long and satisfying duration of time.

Root Rot – It is easy to avoid root rot in these plants. Be careful to avoid overwatering. Allow the soil to dry out completely between waterings.

If the soil stays wet, your climbing onion is likely to develop root rot as the plant experiences water stress and fungal pathogens attack. If you notice that the bulb has turned soft and mushy, this is a sure sign that rot has settled in. The simplest way to deal with root rot is to prevent it.

Frequently Asked Questions

This may not be the most common houseplant available, but you will occasionally see them for sale at greenhouses and nurseries alongside other houseplants. You can also find them online from specialty growers. If you happen to know someone with a plant, ask if they have an extra bulb they could share with you. When it matures and produces offsets, you can share them with your friends.

A well-cared-for climbing onion can be a very long-lived houseplant! They can easily live 10 years or more. In fact, as you continue to divide the bulb offsets, you can essentially keep your plant growing indefinitely.

If you live in plant hardiness zones 10 or 11, you can grow these plants outside year-round. When they go dormant outdoors in a warm climate, cover them with a thin layer of loose mulch to protect them from any unexpected cold. If you maintain your plants in pots, bring them inside anytime the temperatures drop below 50 degrees Fahrenheit (10 degrees Celsius).

Final Thoughts

Climbing onion plants are easy to grow, low maintenance, and make very rewarding houseplants. They don’t take up too much space, are interesting to look at, and don’t require any special treatment. As long as you have a sunny window, warm temperatures, and a little bit of space, you should be able to easily grow your own. Enjoy watching it cycle between active growth and dormancy, and keep an eye out for its tiny flowers!



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