Origins of brain bactus
Mammillaria elongata cacti, commonly known as lady fingers, have a straight growth habit. However, the crested form displays stems with lots of kinks that grow in one big, round clump. The origin of this trait is thought to be a mutation or possibly physical damage.
All succulents, including cacti, have a center of growth called the apical meristem. If the apical meristem is chewed by an insect or somehow damaged, the cactus may start to grow in a wormlike shape. Though rare, sometimes a mutation happens in the cells of a cactus and causes it to become crested.
The right soil is extremely important
Taking care of a brain cactus is easy, but there are a few things to be aware of, especially if you are propagating.
They require the proper type of soil. The best cactus soil is one that drains quickly and thoroughly, such as a commercial succulent soil or a homemade soil mix composed of 3 parts potting soil, 2 parts sand, and 1 part perlite or pumice.
A top dressing of pea gravel will help keep water off the plant.
Watering guidelines for ideal growth
Most cacti don’t require a lot of water, and the brain cactus is no exception. Excess water can get in the folds of the crests and quickly rot it, so be careful when watering. Don’t get water on the body of your brain cactus.
Use the drench and dry method. Water until it runs out of the drainage hole in the pot. Wait until the soil is completely dry to the touch before watering again.
Cacti have a reputation for needing very little water. The drench and dry method mimics the weather patterns in their native desert environment. Deserts get periods of heavy rain followed by long periods of intense drought. Cacti soak up and store all the water they can during heavy rains and dry out during the drought, drawing on their water reserves to stay hydrated. Soaking and then drying out best mimics those conditions.
Soak these cacti once every week or two during the summer and once every four to six weeks during the winter.
How to safely repot a brain cactus
Be careful of the spines. Put on a thick pair of gardening gloves before you try to pick it up. Fill the new pot with fresh cactus soil, leaving some room for the plant and its roots.
Take your cactus out of its old pot. If necessary, run a trowel around the edges of the pot to loosen the soil. Gently pick up the cactus and shake as much of the old soil out of the roots as you can. Put it in the new pot and add fresh soil to fill to the top of the pot. Don't water for a few days in order to give the plant a chance to acclimate to the new container.
You should repot your brain cactus once every two to four years in the spring. If you see roots coming out of the drainage hole, it’s outgrowing the pot and needs to be repotted as soon as possible.
Like most cacti, the brain cactus likes bright, direct sunlight. However, to prevent scorching, do not leave it in the hot summer sunshine for more than four hours.
When growing this cactus indoors, place it near the brightest window in your home to ensure it gets enough light. A southern exposure is preferable.
Brain cacti are not cold-hardy. They will need to be inside for the winter and can’t handle even light frost. Bring them indoors at the start of Fall.
Fertilize a brain cactus about once a month during the growing season in the spring and summer using a water-soluble cactus fertilizer.
Want to try propagating brain cactus?
Because it's crested, propagating Mammillaria elongata ‘Cristata’ is a lot different than propagating other cacti and succulents. You will need to be creative with your technique in order to preserve its unique shape.
This plant does produce offsets that can be divided and replanted, but these offsets usually have a normal growth pattern that’s more like Mammillaria elongata. However, this is not always the case. You can try to replant the offsets and see what happens.
You can also propagate the brain cactus from cuttings, but those cuttings should be grafted onto another cactus for best results. Cut off the very top of the plant you are using for the bottom, take a cutting from your brain cactus, and put these together to create one new cactus. If you put a cutting from your brain cactus on top, the new cactus will have the same characteristics and crested shape, which isn't always true for other methods of propagation.
Grafting works best if the two plants you use are closely related genetically. If you have a Mammillaria elongata, you should graft onto that. If you can’t find a cactus that’s the same species as your brain cactus, try to use a cactus in the same genus.
Cacti and succulent containers
That's my pot of brain cactus pictured at the top of the page. An easy do-it-yourself project for making your own pots that children will enjoy is upcycling old dolls heads into fun containers.
Plain and fancy glass terrariums also make ideal displays.