How Often Will A Starfish Cactus Bloom And When?

One look at the interesting starfish-shaped blooms and it's easy to see why despite the smell, starfish cacti (​Stapelia​ spp.) are popular plants. Also called carrion flower due to the flowers giving off a rotting meat aroma when in bloom, flowering plants are sure to be attention-grabbers indoors and outside. However, when they will bloom depends various things like the plant's age, where it's growing and its care.

Starfish cacti are succulents native to South Africa, all producing starfish-shaped flowers and long, slender, spiked branches. It gets is common name carrion flower due to the flowers attracting flies not only because of their potent smell but also because of the soft white fur that covers the flowers and resembles mold covering rotting flesh. All are frost tender and thrive in consistently warm climates.

There are about 100 species in the plant's family, Apocynaceae, and around 50 different species in the genus Stapelia. Two of the more popular varieties are the giant carrion flower (​Stapelia gigantea​, USDA zones 9-10), producing 14-inch diameter yellow flowers with red stripes and large carrion flower (​Stapelia grandiflora​, zones 10-11), producing large, hairy blooms with yellow and red ridges. They all have the green branching arms that are tinged red in high-sun situations. The arms are barbed with thick white spines. The stems have four angles arrayed up the length and are an inch thick on average.

Some selections of starfish cacti are considered rare, a condition caused by loss of habitat and don't contain the rotting smell. ​Stapelia erectiflora​ and ​Stapelia flavopurpurea​ (both hardy in zones 10-11) bloom with flowers containing a sweet scent.

The flowers of the starfish cactus may extend 14 inches across, depending on the particular species. The flowers are five-pointed and flesh-colored, although some have a grayish or yellowish cast and others have a rosy or purplish glow. The larger species bear flowers at the base of the plant and smaller blooming species may have flowers scattered over the cactus. Each flower only lasts a few days but may die out and become replaced by another bloom. The petals have a grainy texture and pores that resemble skin.

The blooming time of starfish cacti depends on where they are being raised, the amount of sun and water they receive, the fertility of the soil and the species. On average, you can expect a baby plant to bloom in two years with just one or two flowers. When it is mature, the plant will bloom successively in July to September in North America. They flower in November through March in South Africa where they are native. Blooms are rare and rely on prime growing conditions.

The stench is the attracting part of the flower, but its resemblance to flesh actually confuses flies into laying their eggs on the interior. The interior structure of the flower is webbed, which traps the legs of the flies. As they struggle, a pollen packet that is attached to the insect's leg is released and they move on to the next flower. After the flower has finished blooming, it sheds the petals and the ovary swells if fertilization has been successful. Eventually, the ovary bears a number of slightly hairy seeds. Seed is easy to start, but the plant will not bear flowers for many years.