Moon cactus, often seen in vibrant hues in garden centers, is a unique plant composed of two different cacti grafted together. The colorful top part, known as the scion, is typically a Gymnocalycium mihanovichii, a cactus mutant that lacks chlorophyll. This upper portion is joined to a green rootstock, commonly Hylocereus undatus, which provides the necessary chlorophyll for photosynthesis and sustains the entire plant. While primarily grown for their ornamental appeal, these grafted cacti can, under certain conditions, produce fruit.
Characteristics of Moon Cactus Fruit
Moon cactus fruit is generally small and berry-like. Its shape is often spindle-shaped or broad-spherical, developing on the colorful scion. Unripe, the fruit may appear grayish-green, ripening to a reddish, pink, orange, or yellow hue.
It typically measures 1 to 3 inches long and less than 1 inch wide. The fruit is fleshy and contains numerous small black seeds. These fruits result from successful flowering and pollination on the Gymnocalycium scion.
Edibility and Taste of Moon Cactus Fruit
Moon cactus fruit is technically edible. However, it is not widely sought after for its flavor, often described as bland or mildly sweet. Some compare its taste to dragon fruit, which also has a mild flavor.
While all cactus fruits are edible, palatability varies greatly among species. Moon cactus fruit does not typically offer a strong or distinctive taste compared to more commonly consumed cactus fruits like prickly pear. Therefore, it is not a primary reason for growing these plants.
Formation of Moon Cactus Fruit
Moon cactus fruit develops from flowers on the Gymnocalycium mihanovichii scion. These funnel-shaped flowers range from pale green to brownish-yellow, or sometimes red and pink. Flowering occurs in late spring to early summer.
Successful pollination of these flowers is necessary for fruit formation. Moon cacti can self-pollinate, but cross-pollination, often by insects, can also occur. Indoors, where natural pollinators may be absent, hand-pollination with a small brush can transfer pollen from the anther to the stigma. After fertilization, the flower’s ovary enlarges and develops into the fruit, containing seeds. Fruit production is uncommon for many indoor moon cacti due to rare flowering and pollination challenges.
Harvesting and Using Moon Cactus Fruit
Moon cactus fruit is ready for harvest when it ripens to its characteristic reddish color, typically during the summer or fall months. The fruit can be carefully removed from the plant once mature. Handle the fruit gently to avoid damaging the scion.
While edible, its primary use for many enthusiasts is seed collection. The small black seeds within the fleshy fruit can be used for propagation, though growing moon cacti from seed is a lengthy process, often taking at least a year for a recognizable specimen. Alternatively, allow the fruit to remain on the plant, observing its natural life cycle.