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GARDEN JOURNAL

Moon cacti do well on patio, in sunny garden

June 8, 2016

Mutations are often the stuff of sci-fi thrillers with giant ants and superhuman trolls.

Most humans cannot digest lactose after age 4 or 5, but thanks to a genetic mutation most of the decedents of cattle- raising Europeans can digest milk all of their lives, giving this population an excellent source of protein and calcium into adulthood.

One of the most striking mutations in the garden is the so- called moon cactus. You probably have seen these brilliant cactus atop a green base. These mutant cacti showed up in seedlings grown in Japan. These mutants are grafted cacti where the top part lacks chlorophyll thanks to a mutation, and this lack of chlorophyll unmasks the orange, red or yellow colors hidden in most cactus.

Unfortunately, a cactus without chlorophyll soon starves to death and most die while just small seedlings. The solution is to graft this colorful mutant cactus onto a green cactus. This is the so-called Moon Cactus, available as houseplants.

The top cactus is usually Gymnocalycium mihanovichii from South America, and the base, or mother cactus, is often Hylocereus spp.

Moon cactus plant grows best in bright, indirect sunlight. But more isn’t better, and too much sun can actually harm them. So find a place with bright sunlight, but a little shade during the day. A bright windowsill is ideal. You can bring them out to the patio or sheltered sunny garden for the summer.

As you might guess, moon cacti can go awhile between waterings. When you do water them, completely soak the soil so that water runs out the bottom of the pot.

Then do not water them again until the soil dries out. A dry pot of soil will weigh a lot less than one that is fully watered. The No. 1 killer of moon cactus is over-watering, which can cause the roots to rot.

Your colorful moon cactus will probably get along just fine without fertilizer, but from April to September you can give it a once-a-month dose of special cactus fertilizer.

These are not cold-tolerant plants by any means, so be sure to bring them inside on cold nights, and well before autumn temperatures drop. They will do fine indoors all winter.

There are few diseases and insect pests that attack these hardy plants. You might find some mealybugs or spider mites, but again this is unusual.

The moon cactus prefers to be root bound and a little crowded. You can pretty much keep them in their original pot for years on end.

Once in awhile a moon cactus will bloom in late spring or early summer. The dainty flowers are usually pink or red.

The base cactus will often grow faster than the top grafted cactus, and after a few years your pretty mutant may simply split and die.

Whether they will mutate into giant ants or killer tomatoes is another question.

 

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