You can see this mature giant dioon at the Fairchild Tropical Garden in Miami, Florida.
The giant dioon palm is a large, attractive and easily grown plant. Giant dioon has shiny, stiff, light to bright green leaves that grow in an upright nest shape. Technically the giant dioon is not a palm but rather a cycad, a living fossil that is one of the earliest cone bearing plants that trace their origins back to the ancient flora of the early Mesozoic era. The giant dioon is the largest of the American cycads and is known to grow up to 50 ft (15.2 m) high in nature. The typical landscape size for the giant dioon is 5-12 ft (1.5- tall and 6 ft (1.8 m) across. The trunk of the adult giant dioon may grow up to 16 in (40.6 cm) in diameter. Giant dioon leaves are arranged like the vanes of a feather (pinnate), about 5-7 ft (1.5-2.1 m) in length and extending radially out from the trunk. The 140-240 leaflets on each leaf are small, flat, have small marginal thorns and are tapered to a sharp point. The giant dioon is dioecious - it takes two plants to produce viable seeds. The female cones are 12 in (30.5 cm) or more in length and covered with a dense wool. Seeds are cream to white colored, oval shaped and approximately 1.5-2 in (3.8-5.1 cm) long and 1.1-1.3 in (2.8-3.3 cm) wide.
The giant dioon grows in rocky, limestone evergreen forests in tropical Mexico (Oaxaca, Veracruz, Yucatan) at 300-1500 ft (91-457 m) above sea level.
An attractive and easily grown plant, the fast growing giant dioon prefers well-drained soil with regular water. Giant dioon is the most commonly grown Dioon by a considerable margin. Giant dioon will grow in soils having few nutrients, in limestone-rich soils and on moderate slopes. Although tolerant of poor soils, the giant dioon?s growth can be greatly improved through the application of fertilizers. Most growers find that a fertilizer having an even NPK balance, and supplemented with trace elements, provides a good start for cycads. Cycads may then be kept growing well with regular applications of a balanced slow release formulation such as Osmocote® or Dynamite®.
Light: The giant dioon may be grown in partial shade, filtered sun or full sun. Giant dioon prefers partial shade or partial sun to full sun. Moisture: The giant dioon prefers moist to wet soil with good drainage and regular watering for optimal growth. Hardiness: USDA Zones 9B - 11. Mature and established plants have been reported to tolerate temperatures down to 25ºF (-3.9ºC) for short time periods, without incurring significant foliage damage.
Propagation: The giant dioon may be propagated by seeds or by division and replanting of the attractive offsets or "pups" formed at the base of the plant. The seeds of the giant dioon are reported to be exceptionally easy to germinate.
This giant dioon's female cone will burst open when ripe releasing a quantity of large seeds.
Giant dioon is wonderful as a tub plant in a brightly lit spot in the home, on a porch or deck, or in a conservatory. The giant dioon provides an exceptionally exotic but nevertheless formal touch in any garden in warm temperate to tropical climates. A striking approach is to follow the Asian style, with large paired plants in containers or feature beds that flank driveways, doorways or gates. A single large giant dioon makes an excellent feature plant in a landscape emulating a tropical or desert setting, perhaps substituting for a true palm where a large crown is desired without a tall trunk. A giant dioon can also have a spectacular place in a small garden where space is limited. The giant dioon also makes an exotic striking understory plant beneath large trees or any structure that allows at least partial sunlight to pass through.
Use the giant dioon for that very special accent in your landscape. You too can own your very own living fossil, the name often applied to cycads because they have changed very little in the last 200 million years. Giant dioon is considered exceptionally easy to grow - it has not only outlived the dinosaurs but can survive many adverse forces of nature and oversights of the gardening impaired! The genus name Dioon comes from the Greek, meaning "two + egg", because the seeds are borne in pairs. The species name of spinulosum is derived from the Latin, meaning spiny or thorny. The leaves (fronds) of the giant dioon are used in decorations and arrangements.
The leaflets of the giant dioon taper to a sharp point and they also have small thorns. It is well advised to plant the giant dioon away from footpaths and walkways. Wear good gloves when handling or working close to the giant dioon to avoid getting jabbed and stabbed.