The cactus family is known for their distinct spines, areoles, and plump, often ribbed stems. Most cacti come in different shades of green and although unique-looking, they can blend well with other plants, in the wild or indoors.
They are not necessarily vibrant-looking and the colors are often brought about by their showy blooms. But one species has made a name for its brightly bizarre stems and growth – the Moon cactus. If you’re looking for a splash of color in your cactus collection, this novelty plant is for you.
What is a Moon Cactus?
Gymnocalycium mihanovichii var. friedrichii ‘Hibotan’is the scientific name of the Moon cactus. It is a 2-4 in (5-10 cm) globular cactus that got the name from its shape and the smaller “moons” or offsets that appear on the plant upon maturity.
One of the widely cultivated cacti in the genus, it was first introduced in Japan in 1948 offering collectors a range of colors and combinations like red, pink, orange, yellow, and purple. Because of this, they are also called “hotheads”, “ruby ball”, and “neon cactus” (1).
As independently striking as they can be, these cacti cannot stand on their own. Since they lack the chlorophyll needed for their growth, they need the support of other greener and established cacti.
To survive, most neon cacti in the market are grafted onto a sturdy rootstock like the Hylocereus undatus so basically, what we consider a Moon cactus is a combination of two cacti (2).
Caring for Your Moon Cactus
Growing hotheads indoors may seem difficult being in a color-rich and grafted state but it is relatively easy that many enthusiasts begin with this plant. Caring for this cactus is almost the same as when growing a Dragon fruit plant with some additional considerations to keep the Gymnocalycium looking its best.
Light and Water
The Moon cactus needs bright light but not direct sunlight as this will cause the ball crown to scorch. They are ideally placed on the windowsill where they can receive the less harsh morning sun. A series of individually potted Moon cactus also make a striking display in this location (3).
Since the rootstock is an epiphytic plant, it should survive drought as well as slightly moist conditions. However, grafted plants are found to be sensitive to too much water so it is safer to keep the soil on the drier side.
Grafting and Repotting
The Moon cactus needs to be grafted or it will not survive, especially during its vegetative state so a stable dark green rootstock is required not just to provide food but to anchor the plant too.
The Dragon fruit cactus base is ideal because the triangular shape of the stem provides enough surface area that the scion can attach to and it is also an extremely adaptable plant.
The crown will eventually grow bigger and produce offsets so it needs to be regrafted to a new, bigger rootstock.
Repotting your cactus should be done with extra care since grafted plants, although established, tend to be more sensitive. The growing medium must be replaced once every 1-2 years and the soil should be kept quick-draining so a mixture that is high in sand and perlite is recommended (2).
If you love learning about cacti, check these cactus names.
(1) Plant of the Week: Grafted Cactus. University of Arkansas. 2020. (online) https://www.uaex.edu/yard-garden/resource-library/plant-week/Grafted-Cactus-Neon-Cacti-Moon-Cactus-Hibotan-Cactus-11-27-2015.aspx
(2) Staehling, A. Happy Houseplants. Chronicle Books. 2017. P. 96.
(3) Baldwin. D. Succulents Simplified. Timber Press. 2013. P. 272.