The Bishop’s Cap Cactus (Astrophytum myriostigma) is a beautiful and unusual-looking cactus from Mexico. Its common name refers to its resemblance to a bishop’s miter, a cross-section of this cactus is almost startlingly reminiscent of one of these clergy hats. It is sometimes also called the Monk’s Hood Cactus or the Miter Cactus for the same reason. Natively, these plants grow on stony soils at high elevations, taking up calcium through the roots.
There are usually five ribs on a plant, distinct and covered with heavily wooly patches. No spines protrude from the areolas, making this one of the safer cacti to be around. The cactus starts off with rounded stems that lengthen the older the plant gets into a more cylindrical shape. Plants reach maturity after six or so years and begin to flower around the same time. Yellow flowers appear intermittently throughout the year from March to October, bringing consistent color to a garden.
Astrophytum myriostigma Main Characteristics
| Common Name | Bishop’s Cap, Bishop’s Hat, Monk’s Hood, Deacons Hat, Bishop’s Hood, Miter Cactus |
| Botanical Name | Astrophytum myriostigma |
| Synonyms | Astrophytum prismaticum, Cereus callicoche, Echinocactus myriostigma |
| Family | Cactaceae |
| Genus | Astrophytum |
| Type | Cactus |
| Native Range | Central, Northern Mexico |
| Common Cultivars | Onzuka, Ball Nudum Lightning, Dragon, Fire Works, Dragon Hekiran, Fjordhest, Hubuki, Kikko, Spiral Ribs |
| USDA Hardiness Zones | 10 to 11 |
| Mature Size | Height: 0.25 to 2.00 feet; Spread: 0.25 to 0.75 feet |
| Bloom Time | Spring, Summer |
| Foliage | Evergreen |
| Propagation methods | by seeds |
| Sun | Full sun to Partial shade |
| Soil | Dry, Well-drained |
| Toxicity | Non-Toxic |
Astrophytum Myriostigma Care
The Bishop’s Cap Cactus is a slow grower, so don’t be surprised if it doesn’t seem to put on much size in its first few years. However, this plant is quite low-maintenance, making it an excellent choice for beginners, and can easily be grown indoors. And with its distinctive appearance, this cactus is sure to add interest to any home or office.
Light and Location
Bishops Hat does best in bright shade but can tolerate full sun. Growth will be the same either way; it’s just the color of the stem might be more vibrant under light shade. Place the plant somewhere bright but protect it from harsh, direct sunlight in the summer.
Watering
To maintain a desirable shape for the Bishops Hat, you need to follow a precise watering routine. Beginning from March and all the way to October, the watering regimen stays the same. Give the plant little water every week, but check for soil dryness beforehand; you want the potting medium to be as dry as possible before a watering session. Going through this cycle once or twice will give you a rough idea of how long your plant takes to get ready for a new watering session.
Reduce the watering cadence as the colder months start to arrive. Begin tapering off in October and stop watering entirely by November. This is the beginning of the rest period for these plants, and it’s best to keep conditions as dry as possible in these months (till March).
Temperature
The ideal temperature for the Bishop’s Cap Cactus is 70 degrees Fahrenheit. However, it can manage temperatures from 40 to 60 degrees Fahrenheit in winter. If conditions are kept dry, it can even tolerate below-freezing temperatures for brief periods; just don’t let the plant suffer through this kind of cold for too long.
Humidity
Astrophytum myriostigma does best in dry conditions. However, it can tolerate some humidity, up to 50%. If the air is too moist, the plant may be susceptible to fungal diseases. Be especially mindful in the winter, as moist conditions in this season can easily spell death.
Fertilizer
Fertilize Bishops Cap during its growing season, from March to October. A balanced cactus fertilizer will work great, but avoid fertilizers high in nitrogen as this can lead to succulent growth at the expense of the desired shape. Feeding once every two months is plenty.
Cultivars of Astrophytum myriostigma
There are many cultivars of Astrophytum myriostigma. Here are a few:
- Onzuka is wildly popular. It has extremely dense spotting on the stems resulting in attractive designs. Unique designs are highly valued. It is similar to the Superkabuto (Astrophytum asterias cultivar)
- Ball Nudum Lightning is a small, round cactus with startling white marking resembling lightning.
- Dragon is a rare sight. It has outgrowths between ribs that overtake them entirely with age.
- Fire Works is heavily wrinkled, with white markings scattered on the ribs. The uneven markings look like fireworks.
Propagating Astrophytum myriostigma
The easiest way to propagate the Astrophytum myriostigma is by seeds. They should be surface-sown on a soil mix that drains quickly and kept warm (at least 70 degrees Fahrenheit). Water lightly and wait for germination, which typically takes a couple of weeks. Young plants can then be transplanted into individual pots.
Some people have also tried propagating these plants by cuttings. But this isn’t practical as cuttings rarely take root and have a high chance of failure.
Another option is grafting; this is known to work but rarely as a propagation method. Grafted specimens are cultivated to increase the appeal of the end product rather than a means of propagation.
Potting and Repotting Bishop’s Cap Cactus
The Bishop’s Cap Cactus enjoys well-drained soil. It grows on stony soils in its native habitat, so a potting mix that mimics this is ideal. A good potting mix for these plants would be two parts coarse sand, one part perlite, and one part vermiculite. Standard cactus mixes are also applicable. When choosing a pot, find one with a decent-sized drainage hole in the bottom. Clay pots work best are they are the fastest-draining.
Astrophytum myriostigma is a slow grower and will stay perfectly happy in the same pot for many years. With that being said, you may want to repot your plant every 3-5 years or so to refresh the potting mix. Use a well-draining cactus mix and a pot with drainage holes. When repotting, handle the plant carefully as its roots are delicate.
To repot, gently remove the plant from its pot and tease away any loose soil from the roots. Remove any damaged or dead roots and then repot in the same pot using fresh soil mix. Tamp the soil down gently and water well.
Toxicity
Astrophytum myriostigma is non-toxic to both people and pets.
Common Pests and Diseases
Bishop’s Cap is susceptible to mealybugs and scale insects. These pests can easily mask themselves under the areolas’ wooly growth, so check regularly. If any pests attack the plant, treat them with an appropriate insecticide.
Common Problems
One common problem with Astrophytum myriostigma is root rot. This happens when the plant is kept in too much moisture, and can easily lead to the plant’s death. Be sure to plant in fast-draining soil and only water when the soil is dry to the touch. If you suspect root rot, remove the plant from its pot and check the roots. If they are mushy or have turned black, then the plant has root rot and will need to be disposed of.
Tips For Growing A Healthy Bishop’s Cap Cactus (Video)
Attribution
“Astrophytum myriostigma” by sergioniebla is marked with CC BY-SA 2.0.