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 You are here    Flowers by the Sea / Everything Else / Asclepias physocarpa

Asclepias physocarpa


(Swan Plant) Elegant white flowers with purple inner markings change into lime green-to-gold balloon-shaped seedpods in this South African milkweed that Monarch butterflies love. The seedpods are 2 to 2 1/2 inches in diameter.

Price: $11.50
Degree of Difficulty
Degree of Difficulty
This plant is easy to grow in a variety of conditions.
Common name
This is the non-scientific name used for a plant. A plant may have several common names, depending on the gardener's location. To further confuse the matter, a common name may be shared by several completely different plants. At Flowers by the Sea, we rely on the scientific name to identify our plants and avoid confusion.
Swan Plant
USDA Zones
The U.S. Department of Agriculture plant hardiness zones indicate the temperature zones where a plant is likely to thrive. It is determined by the average annual winter minimum temperature. Actual winter temperatures may be higher or lower than the average.
8 -11
Size (h/w/fh)
The anticipated mature size of the plant: Height, Width & Flower Height.
This is the average amount of sunlight that a plant needs to thrive. Generally, full sun exposure is 6 or more hours of direct sun daily while partial shade is less than 4 hours of sun or dappled shade all day. Plants may tolerate more sunlight in cooler climates and need afternoon shade in extremely hot climates.
Full sun
Soil type
This is the kind of soil that a plant needs to thrive. Most plants require a well-drained soil that allows the water to soak into the soil without becoming soggy. Sandy and clay soils can be improved by digging in compost to improve drainage.
Water needs
Plants have specific water requirements. Water loving means the plant needs regular watering to keep the soil moist. Average generally indicates applying 1 inch of water per week, or watering when the soil is dry to a depth of 3 to 4 inches. One inch of water is equal to 5 gallons per square yard of soil surface.
Water loving
Pot size
This is the size of the pot your plant will arrive in. All will be well rooted & branched and ready to grow when planted. Our 3 1/2 inch pots have a volume of 1.0 pints or 473 ml.
3 1/2 inch deep pot
Container plant?
"Yes" indicates that this plant can be successfully grown as a container plant.
Hummingbird plant?
Hummingbirds have been observed regularly feeding from this plant's flowers.
  • Asclepias physocarpa
  • Asclepias physocarpa
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Ratings & Reviews

(Swan Plant) Elegant white flowers with purple inner markings change into lime green-to-gold, balloon-shaped seedpods in this South African milkweed that Monarch butterflies love. The seedpods are 2 to 2 1/2 inches in diameter.

Although most people refer to Swan Plant scientifically as Asclepias physocarpa, it was renamed in 2001 as Gomphocarpus physocarpus to indicate that it is an African milkweed.

It's the graceful flowers on long, slender stalks that give Swan Plant its name. However, it's also commonly called Goose Plant and -- for obvious reasons -- Balloon Plant.

Swan plant is a good back row choice for borders and flowerbeds, because it grows tall. It has long, narrow, lance-shaped leaves on which Monarch (Danaus plexippus), Queen (Danaus gilippus) and Soldier (Danaus eresimus) lay their eggs.

Milkweeds are the only plants that Monarch caterpillars will eat. The roughness of fuzzy milkweed foliage makes it easier for eggs and chrysalises to cling to the plants. Monarch caterpillars consume powerful chemicals in the leaves protecting them as babies and adults against predators for whom the chemicals are toxic. Perhaps it is these chemicals that make deer avoid the plant.

Unlike Common Milkweed (Asclepias syriaca), this plant doesn't have a taproot. This means that it is easier to control the plant's spread.

Swan Plant does well in a variety of average garden soils, requires full sun and -- similar to other forms of the species -- tolerates heat. Although it loves ample water, average watering based on local conditions is sufficient.

While it is perennial to regions with warm winter climates, Swan Plant is a good annual for areas with cold winters. You can overwinter it in a pot indoors in a cool, sunny location. Cut back the foliage first.