How to Grow and Care for Brain Cactus

Brain Cactus Care

Here are the basic requirements for growing brain cactus:

• Grow in a location that receives several hours of bright, direct sunlight.
• Allow the soil to dry out between waterings and avoid humid locations.
• Plant in a sandy, well-draining soil.
• Use a low-nitrogen fertilizer during each watering in the spring and summer months.

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Light

Brain cacti thrive with plenty of sunlight. Several hours of bright, direct light every day is ideal. Indoors, this is best achieved in front of a south-facing window or under a grow light. These cacti are not well-suited for partial or low-light locations, which can make them more susceptible to root rot, stunted growth, and leggy growth.

Soil

These cacti do not like to sit in wet soil, so a sandy, well-draining soil mix is ideal. Commercial cactus and succulent mixes are perfect, or you can make your own at home. Combine equal parts potting soil, sand, and perlite for a well-draining DIY cactus soil that your plant will love.

Water

The brain cactus is sensitive to overwatering and should be allowed to dry out thoroughly between waterings. Overwatering is one of the fastest ways to kill it, so underwatering is always better than overwatering. 

Allow the soil to dry completely and water well, soaking the soil and allowing any excess water to drain from the pot’s drainage holes. Avoid getting water on the cactus itself, as it is susceptible to rot if moisture gets trapped in the plant. Cut back on watering in the winter when the plant is not actively growing.

Temperature and Humidity

Native to hot, arid climates, the brain cactus requires warm, dry conditions. Excess humidity can be just as damaging as overwatering. These factors make it an excellent houseplant since average household temperature and humidity levels are ideal for it. If you want to grow this cactus outdoors, it is hardy in USDA zones 10 to 11; otherwise, it needs to be brought inside for the winter.

Fertilizer

Cacti generally don’t require a lot of fertilizer, and the brain cactus is no exception. It can benefit from extra nutrients during its active growing period (spring and summer). 

Be sure to use a low-nitrogen fertilizer, such as a 5-10-10 blend or a specialty fertilizer designed for cacti, and dilute it with water. Adding fertilizer to your watering can each time you water your brain cactus is an excellent choice since cacti enjoy being lightly fertilized regularly rather than heavily fertilized once every couple of months.  

Propagating Brain Cactus

Propagating brain cactus can be a bit tricky due to its unique growth pattern. This plant does grow offsets, which can be removed and potted separately. However, they usually have the Mammillaria elongata’s straight growth pattern rather than the ‘Cristata’s’ characteristic brain-like appearance. 

Stem cuttings are the most reliable way to propagate this plant, although these cuttings should be grafted onto another cactus for the best chance of success. Be sure to choose another variety of Mammillaria elongata to graft your brain cactus. While grafting sounds complicated and intimidating, it is pretty simple to do by following just a few simple steps. 

1. Take a cutting from your brain cactus using a sharp, clean knife. Ensure you have heavy-duty gloves on to protect your hands. 
2. Cut the top off the rootstalk (i.e., the cactus you will be grafting to). 
3. Place the brain cactus cutting directly on top of the roostalk, ensuring the open cuts are positioned against one another. 
4. Use some elastic bands to secure the two pieces together.
5. Place the grafted cactus in a location that receives bright, indirect light. Too much sunlight can scorch the plant at this delicate stage. 
6. Remove the bands after two to three weeks or once the two pieces have bonded. 
7. Slowly acclimate the plant to a direct sun location—water as usual.

Potting and Repotting Brain Cactus

Brain cactus should be repotted once it outgrows its old container. Since this cactus is relatively slow-growing, you will likely only need to repot it once every couple of years.

Choose a pot that is only 2 to 4 inches wider than its previous container. Terracotta planters are popular for cacti of all kinds since the clay helps wick away excess moisture in the soil. Before you begin repotting, ensure you have a pair of heavy-duty work gloves or leather gardening gloves to protect your hands.

1. Remove the cactus from its old pot and brush away as much of the soil as possible from the roots.
2. Place the plant in its new container and add fresh potting soil around the roots. 
3. Water the cactus thoroughly, allowing the excess water to drain from the pot. 

Common Pests and Plant Diseases

Like most cacti, the brain cactus is fairly resistant to pests and diseases when grown indoors. However, two main ailments to watch out for are mealybugs and root rot. 

Mealybugs are small, fuzzy white bugs congregating in a plant’s crevices. They can spread quickly and are difficult to get rid of. Isolate your plant immediately and follow the steps to get rid of mealybugs if you suspect your brain cactus is infested.

On the other hand, root rot is almost always a result of overwatering. It can be challenging to catch and even harder to save your plant from. Signs of root rot include mushy stems and roots, waterlogged soil, and a shriveled appearance of your cactus. 

Common Problems With Brain Cactus

Brain cacti are hardy and generally problem-free. However, there are a few ailments to watch out for. Since cacti are slow-growing, it can take a while for problems such as mushy stems or brown spots to appear. This means that sometimes, by the time you notice the problem, it may be too late to save your plant. Taking action as soon as you notice any issues is crucial. 

Mushy Stems

Mushy stems and roots are key signs that your plant is suffering from root rot. The only way to save a cactus from root rot is to remove it from the soil, cut away any rot, and re-root the remainder of the plant in fresh soil. Follow the steps for propagation to re-root a plant that has suffered from root rot.

Brown Spots

Hard and calloused brown spots on a brain cactus can result from damage to the plant, an indication of pest activity, or a natural part of the plant’s growth (developing a woody stem on old growth). Examine your plant closely to determine the root cause of the spots.