How Often Will a Starfish Cactus Bloom & When?

The starfish cactus is also called carrion flower due to the strong unpleasant odor of its fleshlike flowers. The plant is a succulent from South Africa with starfish-shaped flowers and long, slender, spiked branches. The flower attracts flies not only with its potent smell but also with the soft white fur that covers the flower and resembles mold covering rotting flesh. There are about 100 species in the plant's family, Asclepiadaceae, which includes several other fly-attracting blooms.

Several varieties of the starfish cactus exist. 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. The plant itself reaches 9 inches tall and has a wider spreading habit. Some of the varieties of cactus are considered rare in South Africa, a condition caused by loss of habitat.

The flowers of the starfish plant may extend 10 inches across. The flowers are five-pointed and flesh-colored, although some have a grayish cast and others have a rosy 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 variety. 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 upon 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 is attached to the insect's leg and they move on to the next flower. After the flower has finished, it sheds the petals and the ovary swells. Eventually, it bears a number of slightly hairy seeds. Seed is easy to start, but the plant will not bear flowers for many years.