Agave havardiana aka Havard Agave

Agave havardiana forms a medium-to-large rosette that typically reaches 60-90 cm (2-3 ft) tall and 90-120 cm (3-4 ft) wide at maturity. Growth is slow, taking 20-40 years to reach flowering size. When it finally blooms, the candelabra-like flower stalk can shoot up to 3-7 meters (10-12 ft) tall before the rosette dies. This monocarpic species rarely produces offsets, so each plant usually remains solitary.

Agave havardiana is one of the most cold-hardy century plants, tolerating temperatures down to -12°C (10°F) or lower when kept dry. It thrives in USDA zones 5-9. The key to winter survival is excellent drainage—this agave can handle extreme cold but will rot if exposed to winter moisture. In regions with wet winters, grow it under an overhang or in a container that can be sheltered.

After 20-40 years of growth, Agave havardiana produces a spectacular flowering event in summer (June-August). A massive candelabra-shaped stalk rises 3-7 meters tall, bearing 12-20 lateral branches covered in clusters of fragrant golden-yellow flowers. The flowers attract hummingbirds, bees, and are primarily pollinated by bats at night. Like all agaves, this species is monocarpic—the rosette dies after flowering, leaving any offsets to carry on.

Agave havardiana has a remarkable mutualistic relationship with the endangered Mexican long-nosed bat (Leptonycteris nivalis). When these bats migrate through Texas, they feed exclusively on this agave species. As bats feast on nectar at night, pollen coats their fur and transfers between plants, boosting genetic diversity. Studies show that without bat pollination, agave seed production drops to just 1/3000th of normal levels. This coevolved relationship makes both species critical to each other's survival.

Agave havardiana is one of the best century plants for cold climates, thriving in USDA zones 5-9 and UK hardiness zone 7. Native to elevations of 1,200-2,000 meters in the Big Bend region, it naturally experiences cold winters. The critical factor is drainage—plant in raised beds, rocky slopes, or add gravel to soil. In wet winter climates, position under an overhang or cover during prolonged rain. Avoid any frost pockets where cold, wet air settles.

Agave havardiana can be propagated from offsets or seeds. Since this species rarely produces offsets (it's typically solitary), seeds are often the primary method. Sow seeds in well-draining mix at 25°C (77°F) or above; germination takes 4-12 days. Keep seeds moist but not wet, covered with plastic to retain humidity, in bright indirect light. If offsets do appear, remove them in spring or summer, let the cut callus for several days, then plant in gritty compost. Roots develop in 2-3 weeks.

Agave havardiana requires minimal pruning. Remove dead or damaged outer leaves as needed by cutting them at the base with a sharp knife. The sharp terminal spine and marginal teeth can be trimmed for safety if the plant is near walkways. After flowering, the entire rosette dies and should be removed. Wear thick gloves when pruning—the sap can cause skin irritation and the spines are wickedly sharp.

When growing Agave havardiana in containers, use a very porous mix (2 parts peat moss, 1 part loam, 1 part pumice or perlite). Repot when roots fill the container, typically every 2-3 years for young plants. Choose a heavy pot to prevent toppling—terracotta works well as it allows soil to dry quickly. Ensure excellent drainage holes. Repot in spring when growth resumes. Handle carefully with thick gloves to avoid the sharp spines and caustic sap.

Agave havardiana has no serious insect or disease problems and is notably deer and rabbit resistant. The main threat is root rot from poor drainage or excess moisture, especially in winter. Fungal diseases can occur if the crown stays wet. Agave snout weevil (Scyphophorus acupunctatus) can occasionally affect agaves, causing sudden collapse—remove and destroy affected plants to prevent spread. Good drainage and air circulation are the best preventive measures.

Agave havardiana has a long history as a food source for Native Americans, particularly the Mescalero Apache and Lipan Apache peoples. The central heart was pit-roasted in earth ovens for about 2 days, converting inedible compounds into sweet, molasses-flavored sugars. Warning: raw agave is toxic—the caustic sap burns the mouth and contains harmful saponins. Only consume agave that has been properly slow-cooked using traditional methods.

Beyond food, Agave havardiana provided valuable materials for Native American tribes. The strong fibers were woven into sandals, baskets, nets, and cordage for traps and snares. The woody flowering stalks served as lance shafts and tool handles. Cooked crowns yielded a brown paint or stain. Today, this species is primarily valued as an ornamental for xeriscaping, rock gardens, and southwestern landscapes, and for its ecological importance as food for the endangered Mexican long-nosed bat.