How to Grow and Care for Starfish Cactus

The Starfish Cactus, known to botanists as Stapelia gigantea, is a distinctive succulent often called the Carrion Flower. Despite its common name, it is not a true cactus but belongs to the milkweed family. Its most notable feature is its massive, star-shaped flower, which can span up to 14 inches and has a unique, velvety texture. This plant’s unusual bloom and straightforward care make it an interesting specimen for indoor gardeners.

Core Care Requirements

Light

This plant thrives in bright, indirect sunlight. An indoor spot near a sunny window is ideal, but it should be protected from harsh, direct midday sun, which can cause sunburn. Outdoors, provide at least six hours of bright sun with some filtering during the most intense part of the day. A reddish or purple tint on the stems indicates the plant is receiving a lot of light, which is a natural protective response.

Soil

A gritty, well-draining potting mix is necessary to avoid waterlogged roots, a primary cause of rot. Standard cactus or succulent mixes work well, and their drainage can be improved by adding perlite, coarse sand, or fine gravel. Using unglazed terracotta or clay pots is also advantageous, as the porous material helps wick moisture from the soil, allowing it to dry more thoroughly between waterings.

Water

This succulent is highly susceptible to overwatering, so use the “soak and dry” method. Allow the soil to dry out completely before watering again. During the active growing season of spring and summer, the plant requires more frequent watering than in its dormant winter period, when watering should be significantly reduced. An indicator that the plant needs water is when its plump stems begin to look slightly shriveled.

Temperature and Humidity

Native to South Africa, the Starfish Cactus prefers warm temperatures and low humidity. The ideal temperature range during the growing season is between 70°F and 95°F. It is not frost-tolerant and must be protected from temperatures below 50°F, so it is best grown in a container that can be moved indoors during cold winters.

Fertilizer

This plant is not a heavy feeder and requires minimal fertilization. If you choose to fertilize, do so sparingly during the spring and summer growing season, applying a balanced cactus fertilizer diluted to half-strength once a year. Excessive fertilizing can lead to lush stem growth at the expense of flower production.

Encouraging and Handling Blooms

Sufficient light is a primary requirement for flowering. Allowing the plant to become slightly root-bound in its pot can also encourage bloom production. A cooler, drier rest period during the winter months helps trigger flowering when the growing season begins in spring.

The flower is famous for its pungent odor, often compared to rotting flesh, earning it the name Carrion Flower. This scent is an evolutionary adaptation to attract its primary pollinators, such as flies. These insects are drawn to the flower believing it is a food source and inadvertently assist in pollination. The strong smell lasts for less than a week while the flower is open.

Propagating Starfish Cactus

This plant is easily propagated through stem cuttings, as its stems are naturally segmented. Begin by taking a cutting of a healthy stem, about 3 to 4 inches long. It is important to allow the cut end to dry and form a callus over a few days; this prevents the cutting from rotting when planted.

Once the callus has formed, plant the cutting in a well-draining soil mix similar to what is used for a mature plant. Place it in a location with low light and keep the soil only lightly moist. Avoid overwatering the new cutting, as this can quickly lead to rot before roots have a chance to form.

Common Issues and Solutions

The most frequent problem is stem rot, which results from overwatering. Symptoms include stems that become soft, mushy, and yellow, particularly at the base. To remedy this, cut away any rotted sections of the plant. Healthy portions of the stems can be repotted in fresh, dry, well-draining soil.

Mealybugs are a common pest that can affect the plant. These small, white, cottony insects cluster on the stems and at the joints, feeding on the plant’s sap. For minor infestations, they can be removed by dabbing them with a cotton swab dipped in rubbing alcohol.