The agaves are native to North, Central and South America, and the West Indies. They range from small to enormous sizes and take many different shapes and forms. Each plant consists of at least one rosette of stiff or fleshy leaves, almost always tipped with a spike and often armed with marginal teeth, all of which make agaves some of the most interesting of all succulents.
Leaf color ranges from dark green to blue-green to blue-gray or gray, and leaves may be striped with cream, yellow, or lime-green. Margins or teeth and leaf tips are gray to dark brown. Many agaves develop branched spikes of yellow, white or sometimes pinkish tubular flowers from several feet to as high as 30 ft. Some bloom annually; although with certain species it can take years for flowering to occur. After a stem flowers, the main plant dies but is usually followed by the outgrowth of small plants called "pups" that form around its base. These can be separated from the parent plant for propagation or allowed to grow in situ and replace the dead mother plant.
The wide variety of sizes, shapes, and growth habits of agaves encourages a number of garden uses. Large species make dramatic statements as specimen plants, and smaller varieties work well in combination with other species in garden beds. Grouping multiple types of agaves in containers can also yield a dramatic effect, albeit a much smaller one. Potting and repotting can be tricky because of the sharp spikes and spines.
Most agaves that are available and suitable locally are not bothered by insect pests or diseases and are virtually trouble-free if sited properly.
Almost all agaves require full sun—at least six hours of direct sunlight—for best appearance and growth. They tolerate poor soils and don’t often develop nutrient deficiencies; however, soil with good drainage is essential. Occasional summer water is necessary for established plants in the ground. Periodic water for container plants in summer is required, with frequency depending on variety and size and placement of the pot.
Nearly all species are grown for their beautiful forms that make bold architectural statements despite razor sharp spikes at leaf tips and along margins.
Agave americana (century plant) is one of the largest agaves, to 5-7 ft. high, spreading to 8-12 ft. wide. Leaves are blue to blue-gray, with long sharp brown-black terminal spines and sharply toothed margins. This species tolerates some shade and is drought tolerant with occasional water in summer. It is relatively fast growing, more so with extra summer water, and is frost tolerant to 15-20 degrees. This is a very dramatic specimen plant in the landscape or in a very large container, always located away from foot traffic.
Agave attenuata (foxtail agave) lacks the genus’ normal physical danger, having no spines or teeth. But for most gardens in Sonoma County, it is not reliably frost hardy and suffers damage below about 28 degrees. Medium green pliable sword-shaped leaves grow in a dense rosette. With age, it reaches 3-4 ft. in the ground, smaller in containers, and forms a smooth, curving trunk upon which the plant sits. Unlike most agaves, the leafy rosette stays low to the ground. This agave benefits from part to full shade except in coastal zones and requires somewhat more water than most other agaves. Its relatively delicate nature makes a nice contrast to its tougher spiny cousins.
Agave filifera (thread-leaf agave) grows to 2 by 2 ft. in a somewhat ball-shaped rosette with narrow leaves attractively edged with fine white threads. It takes full sun to light shade and is reasonably drought tolerant, requiring only occasional summer water. This species is hardy to about 20 degrees and is available in compact form in A. filifera ‘Compacta’.
Agave parryi (Parry’s century plant), a frequent garden favorite, has smoky blue-gray leaves with sharp deep brown terminal spines and shark-tooth-like margins. Most interestingly, the fleshy leaves carry an imprint of the leaf above and below, giving each leaf a distinct pattern. It grows to 1 1/2 ft. high by 2-3 ft. wide in the ground after several years, and wants all the sun and heat it can get. It is cold hardy to about zero degrees.
Agave ovatifolia (whale's tongue agave) is a non-clustering agave that does not produce offsets. It grows to about 3-5 ft. tall and wide with green to gray-green leaves lined with small teeth along the margins and a dark 3/4-in. spike at leaf tips. It takes full sun and is drought tolerant but will grow larger with some water. Frost hardy to zero degrees, it tolerates our wet winters better than any other agave species. It looks similar to Agave parryi, but with a more open habit and less distinct marginal teeth.
Agave victoriae-reginae (Queen Victoria’s agave) is another very striking, geometric plant. It forms a small, dense ball-shaped rosette with narrow dark-green leaves that are almost triangular with bright white spineless margins and ridge-markings along the leaves. This agave normally grows to only a foot or so, making it an excellent container plant. Give it full sun to light shade in hotter areas. It is frost tolerant to around 10 degrees.