Leuchtenbergia principis

Botanical Name — Leuchtenbergia principis

Common Name — Agave Cactus, Prism Cactus

Plant Family — Cactaceae

Background

Leuchtenbergia principis is the only species in the unique cactus family Leuchtenbergia. Resembling an Agave with long, tubercle limbs, this sun-loving plant from North-Central Mexico has a large taproot and papery spikes. As it slowly matures, lower limbs drop from the plant where a corky, woody stalk forms. Truly unique, this plant is highly desired by many cactus collectors.

Growth Requirements

Sun

Leuchtenbergia prefer lots of sun. The plant's desire for solar radiation is unusual even for cacti. Providing a spot in direct sunlight outdoors during warmer seasons is highly recommended.
While indoors, keep in direct sunlight on a south facing windowsill.

Temperature/ Humidity

Summer temperatures above 70 ºF are preferred.
If grown outdoors, move them to a sunny windowsill inside in regions where temperatures regularly drop below 50 ºF.

Water

During warm seasons, Leuchtenbergia prefer to be watered regularly. However, to protect the tap root, water only when the soil has dried out entirely. Always error on the side of underwatering.
During the winter, water very infrequently. Maybe even once a month or month and a half. It’s safe to cut back on watering entirely.

Soil/Roots

Leuchtenbergia are native to rocky desert climates. They prefer a gritty, well-draining soil mix. A cactus mix works fine. You can amend it with sand or fine pumice up to 50% to improve grittiness and drainage.

Flowering

Leuchtenbergia reliably flower from tubercle tips when given lots of sun and heat outdoors in the summer. They will produce one or more yellow flowers between spring and fall.
Leuchtenbergia plants flower once they’ve matured. This can take up to four years. Plants that are kept indoors during the summer don't often flower.

Fertilization

Typically, Leuchtenbergia 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. Never fertilize in winter.

Propagation

Leuchtenbergia 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.
Very occasionally, these plants will produce offsets which can be separated and grown independently.

Health

Diseases

ALeuchtenbergia are not especially susceptible to pests or diseases. Keep an eye out for common pests such as aphids, mealy bugs, and scale.
Because of the large taproot, root rot can be a common issue if the plant is exposed to excess moisture and cold.

Maintenance (pruning, legginess, repotting)

Leuchtenbergia plants are very low maintenance. They prefer to be pot bound. Repot them once every two to three years. Early spring is the best time to repot, when they are just waking from their dormancy.

Toxicity