Agave americana -
Agave americana is the 'spikey, cactusy thing' seen all around the Mediterranean reaching a height of around 2m (6 - 8 feet). It is not, in fact, a cactus, but a succulent from the arid parts of SW USA and Mexico. It can take extreme heat, ferocious sun, and frost when large.

It also goes by the common name of Century Plant, which relates to the length of time before it flowers. This, of course, is an exaggeration, as it is nearer 20 years. The flower spikes are huge, reaching up to 10m. They consist of a single flagpole like spike with a candelabra of flowers at the top.
Aggie Agave June 2006
Aggie Agave at Hardy Tropicals, Chalk
Flowering agave americana
Wild Agaves in the desert
After flowering the plant dies, but by that time there will be dozens of offsets of varying sizes to take over.

An ideal plant for well drained, sun baked gardens. Dig in ample amounts of coarse grit and sharp sand at planting time to improve drainage. Mound up in heavy soils and mulch with pea gravel or shingle to stop water sitting around the base of the plant.

Its cold hardiness has only recently been understood, but when you consider its clump forming habit, it becomes clear that the smaller offsets are sheltered by the bigger members of the clump, so they don't need to be as hardy. When they get bigger and the older plants die off, they are fully exposed to low temperatures. For many years small. individual offsets were frozen through. It was only when larger plants survived the connection was made.
I 'obtained' my first Agave americana while on a lads trip to San Antonio, Ibiza, in the summer of 1975. There was a clump of mature plants by the roadside, just begging to have a small offset removed, so I obliged, and Al Agave came home with me.

Al was about 2 inches across with no roots, so I thought he wouldn't survive, but they are pretty resilient.
Ibiza 1975
Aggie Agave in the snow
Aggie in the snow January 2004
Al was potted up in a 5 inch clay pot where he spent the next 9 years. It just shows that you can limit the plant size by the pot size. After 9 years in a 5 inch pot Al was only 12 inches in diameter. Finally, in 1984 Al was potted on into a white 18 inch half tub, where he still is today and about 30 inches across.

Aggie Agave, is one of Al's many offsets. Aggie, was removed from Al in 1994 and potted on properly ending up in a 12 inch pot in 1996. In 1997 I planted Aggie out next to the east facing wall of the lounge. Once in the ground the growth rate accelerated, as did the offset production rate.
Together, Aggie and Al produced an amasing amount of offsets. These have been removed several times, and given away to local people. There are now 6 Agaves in front gardens in my road.

Again this year I have removed the offsets, and potted them up. I have sold several of the larger ones including 2 x 60cm diameter plants. I still have many of the small to medium size plants available. Priced from 50p to 4.50.
Aggie Agave 2003
Aggie Agave 2003 with Al Agave middle right background
Agaves potted
Potted Agaves
Aftercare

In pots, use a loam based compost with about 25% added coarse grit. Water during the growing season April to October in the South. Keep dryer in dormant period and pull into shelter if hard frost is forecast.

Planting out in open ground. If in a mild area (lowland, coastal) plant anywhere in full sun, in colder areas, plant in a sunny, sheltered spot.
Plant in well drained soil with extra grit or gravel added, and mulch with an inch of gravel or stone chippings. Protect from frost when young. I used a newspaper impaled on the spikes when hard frost was forcast. For best growth water in hot weather, but do not water at all in the dormant season. Cut off termi nal spikes to avoid injuring if required.