Agaves have a structural form with eerie beauty. Serrated leaves emerge from a dense basal rosette, spiralling outward. Varietal leaf color variations are extensive; dusty blue, silver grey, green and variegated. Blooming is a rare and spectacular occurrence, with flower spikes towering above the plant.
Agaves are surprisingly cold tolerant, easy to care for, and will grow in even poor soil with good drainage.
Agaves are native to the southwestern United States and Mexico. They are primarily desert plants adapted to very hot weather, minimal rainfall and gritty soil with excellent drainage. Replicating their native habitat is the key to successfully growing these plants.
It is imperative that the soil is well drained. Agaves are tolerant of cold temperatures, but too much moisture will kill them. In some states, heavy winter rains will cause problems with agaves. Growing in a pot or a movable planter is the only option, allowing the plant to be located in a sheltered area during the wet season.
Agaves do well without fertilizer. Potted plants should be given fresh soil every other year. An abundance of offsets will form at the base of older plants, and these should be gently removed and replanted elsewhere or potted up. Too many sprouts crowding the base of the plant are unsightly and can trap excess moisture, causing disease. Some varieties of agave become very large, so leave plenty of room when planting them in the garden.
The number of available agave varieties is staggering. The selection process can be made easier by deciding on foliage color and eventual size.
Agave attenuata forms large rosettes of soft chartreuse leaves. This is an unusual species in that the growth habit is more similar to a tree than an agave. It may need to be staked the first few years to support the weight of the foliage. This is a tropical agave, and is frost tender.
Agave protoamericana x scabra 'Silver Surfer' has dramatic, stiffly upright blue leaves. This agave will take up some space, growing up to 6 feet tall and wide.
Agave americana 'Opal' is a brightly colored variegated type. Leaves are striped with pale yellow along the margins. It is slightly smaller than most americanas, topping out at 4 feet.
Agave parryi grows in a tight clump, looking very different from other species. Foliage is usually silver, with some cultivars green in color. This is a good plant for smaller areas, growing only 2 feet tall and wide.
Agave lophantha 'Quadricolor' has multiple variegation. Leaves have a pale green strip running down the middle, surrounded by dark green bands and yellow margins. Growing only 18 inches tall, this plant is good for small spaces.
Agave flowering is an unpredictable and very rare occurrence. Some varieties will flower after 25 years or more, others within 10. Unfortunately, the plant often dies afterward. Offsets growing around the base will continue to thrive, and can be divided and planted. Despite the death of the plant, blooming is spectacular. The massive flower spike emerges in a few days, and rapidly grows up to 10 feet above the main rosette.
After flowering, remove the spent stalk. The main plant may actually survive the experience, so wait to remove it until it begins to wither. After the agave dies, remove it and allow a few of the offsets to grow in its place.
Determining agave cold tolerance depends on what region each species is native to. Tropical agaves will have much less cold tolerance than those from the American southwest. Agave parryi will survive short periods of minus 5 F, while Agave attenuata will suffer at a light frost.
Increasing cold tolerance involves planting in extremely well-drained soil. Cold temperatures combined with damp roots will cause disease and death. Plants can also be grown in pots and moved indoors. A frost blanket will help plants suffering in an unexpected cold snap. Locating agaves in full sun, on the south or west side of a wall or building, can also increase hardiness.
Agaves are wonderful plants for low maintenance gardens, needing little water or care. They also provide an exotic look, especially when planted with other cacti and succulents. The large size of some specimens requires careful placement. Spines on the terminal ends of the leaves can cause painful wounds, so locate agaves away from sidewalks and high traffic areas. Variegated types look striking planted in pots of contrasting colors.
Very large specimens in the landscape will need to be divided periodically. When pruning and dividing agaves, always wear gloves and eye protection. Not only are the spines dangerous, but the sap can cause contact dermatitis and even severe burns if it comes in contact with skin.