Is this plant safe for pets?

No, it is toxic to dogs and cats if ingested.

Does it need full sun?

Yes, it thrives best in full sun to light shade.

Plant guide

Balloon plant.

Gomphocarpus physocarpus

Pronounced gom-fo-KAR-pus fy-so-KAR-pus

Also known as Balloon Cottonbush, Balloon cotton bush, Old Man's Balls, balloon cotton-bush, balloon plant, bladderbush, cottonbush, goose plant

The balloon plant is a fascinating member of the milkweed family known for its unique, inflated seed pods. It grows as a perennial shrub and serves as a vital host plant for monarch butterfly caterpillars. You will love how these quirky pods add visual interest to any sunny garden bed.

At a glance

Care level: Easy
Plant type: Perennial shrub
Light: Full sun
Indoor light: Direct sun
Water: Every 5 to 10 days
Mature size: 6 feet
Growth rate: Fast
Hardiness: USDA 9 to 11
Bloom time: Summer to autumn

Care

Plant this shrub in a spot with plenty of sun and well draining soil. Watch for aphids on the stems and keep an eye on the soil moisture to prevent wilting during hot spells. Prune back after flowering to encourage a bushier shape and more blooms next season.

Watering: Water deeply when the top inch of soil feels dry to the touch.
Feeding: Apply a balanced liquid fertilizer during the active growing season.
Pruning: Cut back the plant in late winter or early spring to maintain size.
Repotting: Repot when the roots begin to circle the bottom of the container.
Soil: Well draining, sandy or loamy soil
Soil pH: 6.0 to 7.5
Temperature: 5 to 35°C
Humidity: 40 to 70%
Drought tolerance: Moderate
Lifespan: Short lived perennial, often treated as an annual.
Deer and rabbits: High

Signs it needs repotting

Roots growing out of the drainage holes.
Water sitting on top of the soil for too long.
Plant growth slows significantly.

Safety

People: The milky sap is toxic if ingested and can cause significant skin or eye irritation.
Pets: This plant contains cardiac glycosides and is considered toxic to cats and dogs if ingested.
Children: Keep this plant away from children because the milky sap is poisonous and the pods look like toys.
Contact allergens: The milky latex sap can cause contact dermatitis in sensitive individuals.
Airborne allergens: There are no notable airborne allergen risks associated with this plant.
Edibility: This plant is not for consumption as all parts contain cardiac glycosides.

How to identify it

Large, inflated, lime green seed pods
Narrow, lance shaped green leaves
Small, white, star shaped flowers
Hairy, bladder like fruit texture

Height: 1 to 2m
Spread: 0.6 to 1.2m
Leaves: green, evergreen
Flowers: white, 1 to 2cm
Fruit: light green, Autumn

Problems to watch for

AphidsCommon
Milkweed BugsCommon
Root RotUncommon
Sooty MoldUncommon

By symptom

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Growing it

Propagation: seed, cuttings
When to plant: spring, early summer
Overwintering: In cooler areas, bring the container indoors before the first frost. If planted in the ground in frost prone areas, treat it as an annual and replant in spring.
In containers: It grows well in large containers, at least 30 centimeters in diameter, to accommodate its root system.

Seed

1. Collect dry pods in autumn.
2. Sow seeds in well draining soil in spring.
3. Keep moist until germination.

Plant in groups to create a stronger visual impact and attract more pollinators.

Grows well with

Lantana — They share similar sun and water requirements.
Salvia — These provide a nice color contrast to the white flowers.

Similar species

Common Milkweed — It is a related species that also serves as a host for butterflies.

Science

Family: Apocynaceae
Genus: Gomphocarpus
Order: Gentianales
Class: Magnoliopsida
Native range: Southern Africa
Conservation: This plant is not of conservation concern and is considered a weed in some parts of the world.

It grows in disturbed areas and open grasslands where it relies on wind to disperse its seeds.

Value to wildlife: larval host plant, nectar source
Pollinators: bees, butterflies
Uses: ornamental, floral arrangements, butterfly garden

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 6/9
Light: 7/9
Temperature: 7/9
Moisture: 5/9
Nutrients: 4/9

Taxonomy resolved against GBIF.

Questions people ask

Is this plant safe for pets?: No, it is toxic to dogs and cats if ingested.
Does it need full sun?: Yes, it thrives best in full sun to light shade.

Where the name comes from

Gomphocarpus comes from Greek words meaning swollen fruit, referring to the inflated pods.

Good to know

Commonly called hairy balls or balloon plant due to the fuzzy, inflated seed pods.
It is a member of the milkweed family.
The pods are hollow and light, making them float easily.
It serves as a host plant for the monarch butterfly.

Also in

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This guide was generated with AI and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.