Horrida Agave (Mexcalmetl Agave)
Agave Horrida (Mexcalmetl Agave) looks like it’s auditioning for a part in a horror movie—and we absolutely love it for that.
Native to the rocky volcanic slopes and lava fields of central Mexico, this charmingly goth-y little succulent has sword-shaped leaves edged in imposing, tooth-like spikes that start out brown and fade to a ghostly grayish-white.
It’s as if the killer plant Audrey from Little Shop of Horrors had a baby with the shark from Jaws … and possibly also a chainsaw? … and it’s incredible.
Despite its savage appearance, Agave Horrida is easy to tame. Topping out at 1’-2’ high and 2’-3’ wide, it requires little space compared to most agaves (though do give those teeth their due). It needs only the most basic care: Lots of bright sun, minimal water, average temperatures above 50°F … and pretty much nothing else.
Agave Horrida is surprisingly versatile. It’s fantastic as a specimen plant. It also offers a wonderful contrast to plants with softer foliage or different shapes (for example, the Golden Barrel Cactus). Finally, if you feel like a movie night, Agave Horrida will happily join you for a Nightmare on Elm Street marathon—although you may have to help it pick popcorn out of its teeth later.
Characteristics and traits of a Agave Horrida (Mexcalmetl Agave)
Scientific Name: Agave Horrida (syn: Agave Gilbeyi, Agave Grandidentata, Agave Maigretiana, Agave Regeliana, Agave Triangularis var Rigidissima)
Genus: Agave
Family: Asparagaceae (subf: Agavoideae)
Common Name: Mexcalmetl Agave
Indoor: All year in temperatures above 50°F
Outdoor Zones: 9b-12
Type: Perennial evergreen; Propagated via leaf cuttings, seed, and/or division of offshoots/bulbils
Mature Height: 1’-2’
Mature Width: 2’-3’
Plant Height when Shipped: XXXXXX
Growth Rate: Slow
Flower: Rare - Towering central stalk several feet high, covered in bell-shaped flowers, usually followed by death of plant
Foliage: Thick, sword-shaped leaves arranged in a rosette pattern, dark green with impressive, tooth-like spines lining the edges
Plant Care and Advice for Agave Horrida (Mexcalmetl Agave)
Grown In: Inside: all zones year round, Outside: zones 9b-12
Light Requirements: Full sun to part shade
Water Requirements: Water when the top 2” of soil dries out, giving deep drinks in spring and summer (March-August), and small sips in fall and winter.
Drought Tolerance: Excellent
Temperature: Indoors: best between 50°F-90°F. Outdoors: Takes most any heat. Cold-hardy to 30°F, but will take frost damage.
Air Purification: Good
Toxicity: Toxic. When touched, sap can cause burning, pain, swelling, rash and blisters. When ingested, it can cause vomiting and painful stinging and burning of the mouth, tongue, and lips.
Fertilizer: Indoors: Succulent food at half strength April through August. Outdoors: None.
Container Friendly: Yes, but good drainage is vital
Planting:
Agave Horrida is a slow grower and rarely needs to be repotted. When the time does come, choose a quality, fast-draining soil with lots of sand or pebbles. Commercial cactus or succulent mix is ideal.
Handle your Agave Horrida carefully, both because its sap can irritate your skin and because of the spines on its leaves. Be careful to seat it in the soil at the exact same depth it was in its previous pot—planting it deeper can result in soil touching the stem (and holding water against it) too high up, which is a sure-fire way to attract stem rot disease.
Finally, once the plant is in its new pot, withhold fertilizer for at least 3 months to avoid shocking it. The new soil will give it all the nutrients it needs during that time.
Plant Care:
Agave Horrida loves full sun. Inside, a window that gives it at least 6 hours of sunlight a day is ideal. Outdoors, full sun is usually the way to go. However, if you live in an exceedingly scorching location, your agave will tolerate, maybe even appreciate, a bit of afternoon shade.
When moving your Agave Horrida from one place to another, especially if the light or temperature is markedly different, it’s a good idea to do so gradually over the course of a week or two, so the plant can ease into its new environment.
Established Agave Horrida plants require very little water. During spring and summer, give it a deep drink when the soil is dry to a depth of 2”, then let it drain and wait for the top 2” to re-dry before watering again. In fall and winter, use the same dryness test but give much smaller drinks so as to avoid inducing root rot disease.
Humidity is rarely a concern for Agave Horrida, which likes things dry and dislikes humidity-raising devices such as spray bottles and pebble trays. The plant does best at temperatures between 50°F-90°F. It can generally tolerate a little more of both heat and cold, but its growth will stall, and it will begin to suffer tissue damage below 32°F (though the damage may take several days to fully manifest).
As a rule, Agave Horrida does not require fertilizer—in fact, because the plant usually dies after flowering, one could argue that it’s harmful to fertilize outdoor agaves. Indoor specimens rarely flower, so it’s okay to provide them with a half-strength dose of cactus/succulent food monthly from April through August.
Expert Advice:
Agave are practically bulletproof as long as they aren’t overwatered. The most significant pest is also a thankfully rare one: Scyphophorus Acupunctatus, also known as the agave snout weevil. If you see this pest, which looks like a small black beetle with a very long nose, on your agave, it’s probably too late.
The weevil lays eggs on the plant, and in the process infests it with a bacteria that liquefies the plant’s flesh. The bacteria can spread from agave to agave, too, so you may have to sacrifice one plant to save the others. If you live in an area prone to weevil infestation, it may be worthwhile to take preventative measures such as treating your plants with neem oil or insecticidal soap.
Agaves are monocarpic, which means the parent plant almost always dies after flowering. This is rarely an issue for indoor plants, which almost never flower, but can be a concern for outdoor agaves. The bad news is, cutting off the flower spike will not prevent or delay the parent plant’s death. The good news is, the parent plant almost always grows tiny “pups” to take its place.
Agave Horrida can be propagated via those same offshoot pups, bulbils, or by collecting (or purchasing) and planting its seeds.
To propagate through pups, simply gather the pups, let them sit 24 hours so any wounds can seal, then place them in fast-draining succulent soil with plenty of bright light (but not much full sun just yet). Water them in small, but regular amounts until their roots form, then treat them as normal.
Bulbils, which are essentially pups that grow directly on the parent plant’s flower stalk, can be detached (just twist them off with your fingers) and treated the same way. It’s best not to detach them until they have at least four leaves of their own.
For seed pods, allow them to dry on the stalk if possible. When they break open, collect the seeds and plant them in trays filled with sterilized seed starter mix or a 1:1 blend of sphagnum moss and either sand, pumice, or perlite. You can self-sterilize the soil by baking it at 350°F for 30 minutes.
Scatter the seed over the soil (don’t bury them; they need sunlight to germinate), thoroughly moisten the soil with clean, room-temperature water, and cover with clear plastic. Keep temperatures above 65°F, water with a spray bottle every few days, and your seeds should germinate within a month.
Finally, it’s possible to propagate Agave Horrida via leaf cuttings as well. Cut a piece of a mature leaf, let it sit 24 hours to seal its wound, then insert it cut-side-down into fast-draining soil. Keep lightly moist, and you should have baby agaves within several months.