Astrophytum quadricostatum var. nudum
Botanical Name — Astrophytum quadricostatum var. nudum
Common Name — Bishops’ cap
Plant Family — Cactaceae
Astrophytum quadricostatum is one of six species in its genus. The generic name “Astrophytum’ translates from Latin to “star plant”. This species is known for having four ribs, hence the prefix “quad” in its specific epithet. Native to parts of Texas and northern and central Mexico, this cactus grows on the rocky slopes of mountains. It thrives in sunny, arid conditions. The nudum variety lacks the white pubescence found on most other species.
- These cacti prefer lots of sun, at least five hours of direct sun daily.
- Indoors a south facing window is ideal. Outdoors seat them in a place where they will get plenty of sun exposure, but protect them from intense, peak afternoon sun.
- Astrophytums like it hot! Above 70 ºF in the summer is preferred. As these plants are native to North America, they are accustomed to seasonal cool weather.
- During the winter they prefer cooler temperatures, between 50 and 60 ºF. If grown outdoors, give your Astrophytum a sunny spot indoors once temperatures regularly drop below this.
- Astrophytums prefer to stay on the dry side. In the summer water them only when the soil has dried out entirely. Always err on the side of underwatering. They are built to withstand drought, and overwatering is one of the quickest ways to kill them.
- During the winter water very infrequently, if at all. It’s safe to cut back on watering entirely. This will encourage flowering during the spring!
- Astrophytums are native rocky, mountain slopes, and desert climate. They prefer a gritty, sharply draining mix. A cactus mix would work fine. You can amend it with sand or fine pumice up to 50% to improve grittiness and drainage.
- Cacti will produce one or more flowers between spring and summer. Creamy yellow flowers are borne from the apex, giving the appearance of a crown. This makes this plant a gorgeous ornamental specimen.
- Astrophytum plants flower once they’ve matured a bit. This can take up to six years. Exposing your cactus to drought while it is dormant during the winter will encourage blooming during the growing season.
- Typically, Astrophytums do not require fertilization. You can feed them during the active growing season to give them a boost or refresh their soil. Apply a balanced fertilizer diluted at half strength, once a month.
- Astrophytums are typically propagated by seed. Seeds are fragile and have a fairly short shelf life. Be gentle with them and sow quickly after harvesting to improve chances of germination.
- Sometimes these plants will produce offsets which can be separated and grown independently.
- Astrophytums are not especially susceptible to pests or diseases. Keep an eye out for common pests such as aphids, mealybugs, and scale.
- Root rot can be a common issue in the instance of overwatering.
Maintenance (pruning, legginess, repotting)
- Astrophytum plants are very low maintenance. They prefer to be pot bound. Repot them once every one to two years. Early spring is the best time to repot, when they are just awaking from their dormancy.
- Astrophytums are not known to be toxic to humans or pets.
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