Mammillaria Elongata ‘Copper King’ is like many other cacti – it needs little water, likes temperatures on the warmer side (no lower than 30 F/-1.1 C), and prefers shaded to full sun. With this in mind, it’s the easiest to grow outdoors, though indoor growing is possible as well.
Mammillaria Elongata ‘Copper King’ are sensitive to overwatering and can develop root rot if water is allowed to sit at their root level.
To avoid overwatering this cactus, you should water it only when its soil is dry to the touch. The Copper King cactus is drought-resistant and does well even with a limited amount of water.
In cold winter months, the water supply to Mammillaria Elongata ‘Copper King’ should be little to none. The Copper King becomes dormant in the colder months of the year, and it also gets much more sensitive to overwatering in winter than in summer.
Where to plant
The Copper King cactus should be planted in a light-draining cactus mix. This is to encourage draining and to prevent standing water around the roots of the plant.
For extra drainage, you may add some mineral grit like pumice, perlite, or coarse sand to the mix as well. Mineral grit should make up 70-80% of the entire mix.
The pot should also have large drainage holes not to allow water to linger in the soil for too long.
Since the Copper King cactus likes shaded to full sun, it does the best when kept outdoors, whether in a pot or garden soil. This cactus may be kept under direct sunlight all day, but make sure to move it to a shaded location on very hot days to prevent sunburn.
You may also keep the Copper King cactus inside, but be sure to place it in a spot that receives direct sunlight most of the day. Again, shade the plant on very hot days.
In winter, you may want to move the Copper King cactus inside since it is not a frost-hardy plant. If winters in your area aren’t cold though, you won’t need to do this.
General care information
Fertilize the Copper King cactus throughout its growing season, which is spring and summer. Depending on the fertilizer, you should fertilize the cactus once every 4-8 weeks. The fertilizer should be high in phosphorus and potassium.
As the plant grows, you will need to think about moving it to a larger pot at some point. The Copper King is a relatively fast grower, so you should probably repot it every spring. After repotting, keep the plant away from direct sunlight and don’t water it for around a week to allow it to recover.
Frequent repotting is also helpful since it allows you to have a look at the plant’s root health, as well as introduce it to new, high-nutrient soil.