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The Starfish Cactus: A Unique Beauty

The Starfish Cactus, Stapelia grandiflora, is native to South Africa. It is easy to grow and thrives both indoors as a houseplant or outside in the garden. Its impressive blooms catch the eye but their fragrance is less than desirable. Yet, many house plant enthusiasts still prize this cactus for its unique characteristics.

 Stapelia grandiflora
World of Succulents

Starfish Cactus Appearance

The Starfish cactus produces several stems branching out from a central point. The stems are thick-skinned and without spikes. The Starfish plant grows aggressively in the garden and will spread quickly if not contained. When grown in pots, it reaches a height of 10 inches ( 25 cm) and 4 inches ( 10 cm) wide. The large blooms feature five yellow petals with many red or brown speckles to give a mottled appearance. Like the Lifesaver plant, these showy flowers give off a strong odor resembling carrion to attract pollinators. Flowers appear in late summer through fall. 

Starfish Cactus Light Requirements

Provide bright, indirect sunlight for your Starfish succulent. A west-facing window is ideal or a south-facing window with filtered sunlight. The Starfish plant benefits from shelter against the hot afternoon sun which can scorch the foliage. If grown outdoors, full morning sun to partial shade is best. 

Water Needs

The Starfish cactus is drought tolerant and prefers the soak and dry watering method. Water when the soil has dried, then soak until the water runs through the pot’s drainage holes. Allow the water to drain for 10 minutes, then dispose of excess water in the drip tray to avoid root rot. Repeat this process during the spring and summer, and early fall months until blooming has stopped.

Temperature and Humidity

Temperature and Humidity

Provide the Starfish cactus with indoor temperatures around 70 degrees Fahrenheit ( 21 degrees Celsius). Keep temperatures above 50 degrees Fahrenheit during the plant’s blooming season or flowers will not appear. The Starfish plant will tolerate short periods of below freezing temperatures provided it is kept dry. Indoor humidity levels are not a concern for the Starfish succulent but ensure the plant is not exposed to both humidity and cold at the same time or disease may set in.

Soil and Fertilizer

Grow the Starfish cactus in a well-draining soil mix of potting soil amended with perlite and coarse sand. A premixed succulent soil from a garden center is also acceptable. For added drainage, lay a one-inch layer of small gravel at the bottom of the pot to protect the roots from sitting in water. Feed your Starfish plant from spring until blooming is finished once per month with a houseplant fertilizer diluted to half strength. 

Starfish Cactus Propagation

The Starfish plant is propagated either by cuttings or sowing seeds collected from its fruit. To propagate by cuttings, use a sharp and sterlite knife to cut one of the stems near the base of the plant. Sit the cutting on a paper towel for a few days to allow the cut end to form a callus. Plant the cut end in a small pot filled with peat. Place the cutting in low lighting and keep the soil slightly moist until roots form. Transfer the new plant to a larger pot filled with succulent soil or the recommended soil mixture.

To propagate the Starfish succulent by seed, collect seeds from fruit that has broken open on its own. Surface plant the seeds in a succulent soil mix and cover lightly with soil. Keep the soil moist until germination occurs. Transplant the new seedlings into their own pots once they have grown a few inches tall. Fresh seeds germinate quicker than dried seeds.

Wintering the Starfish Cactus

Wintering the Starfish Cactus
Belle’s Greenhouse

In winter move your Starfish plant to a cooler location with temperatures around 50 degrees Fahrenheit ( 10 degrees Celsius). Reduce moisture by watering only enough to prevent the leaves from shriveling. Withhold fertilizer while the plant is dormant. Move the plant to warmer temperatures beginning in early spring and resume regular watering and feedings.

The Starfish cactus makes an excellent addition to any houseplant collection and is a great conversation piece. While it needs extra ventilation during its blooming season, to counteract the flower’s strong scent, its beauty outweighs this issue. 

Starfish Cactus FAQ

Why is My Starfish Cactus Turning Red?

Overexposure to direct sunlight causes the stems of the Starfish plant to turn red. Move your plant to an area that receives filtered sunlight or only a few hours of direct sunlight per day.

Why is My Starfish Plant Drooping?

Overwatering is the leading cause of root rot, which often displays as drooping stems. Reduce watering and ensure the plant’s soil is fast-draining. 

How Often Should I Repot My Starfish Succulent?

Repot the plant once every two to three years or when it has outgrown its current pot. Transfer the plant in the early spring before the growing season begins.

What Pests and Diseases Affect the Starfish Plant?

Mealybugs and root rot are the most common problems with this plant. Combat mealybug infestations by treating the plant with an insecticidal soap. Minor root rot can be treated by trimming any dark or mushy roots and repotting in fresh soil. Reduce waterings to avoid future issues. For advanced cases of root rot, follow up by treating the fresh soil with a mixture of water and 3 percent hydrogen peroxide.

I’ve Noticed an Unpleasant Smell When My Starfish Cactus Blooms. What is it?

The Starfish plant’s blooms produce a strong smell, described as rotting meat, to attract flies and other pollinators in its native Africa. If the scent becomes overpowering, move the plant outside to a location with partial shade until the blooms expire.