Encephalartos whitelockii is a large, spectacular, evergreen, arborescent cycad up to 4 meter tall. Each stem is topped with a crown of long, stiff, dark green, glossy fronds which curve gently backwards. The fronds are composed by falcate, well-spaced, dentate leaflets that curve towards the frond apex and carry more than 3 teeth on each margin. The teeth on the lower margin are also well-spaced rather than crowded to the base. The bluish-green cones with smooth scale apices, the sessile seed cones and the long-stalked, often pendulous pollen cones are also distinctive. The reproductive organs take the form of cones, similar in appearance to those of a conifer, with the male and female cones being borne on separate plants. Male plants of E. whitelockii produce up to five, pendulous, bluish-green cones per stem, while female plants produce up to three, bluish-green egg-shaped cones. E. whitelockii is a long-lived, slow growing plant that always occur as individual male or female plants. There is no way of determining the sex of a cycad until it begins to produce its first cone.
- Stem: Erect up to 4 m tall, 35–40 cm in diameter typically growing in large clumps. The stems although woody in appearance, consist mostly of soft, pithy storage tissue protected by a solid layer of old leaf bases.
- Leaves: 310–410 cm long, dark green, highly glossy, slightly keeled (opposing leaflets inserted at 160° on rachis). Rachis green, gently curved, somewhat lax or straight with last third sharply recurved, not spirally twisted. Petiole straight, with 6-12 prickles, spine-free for 13 cm; leaf-base collar not present; basal leaflets reducing to spines. Leaflets lanceolate, strongly discolors, not overlapping, not lobed, insertion angle horizontal; margins flat; upper margin heavily toothed (more than 3 teeth); lower margin heavily toothed (more than 3 teeth); median leaflets 23–30 cm long, 20–28 mm wide.
- Male cones: 1-5, narrowly ovoid, green or yellow, 50 cm long, 9 cm in diameter.
- Female cones: 1-3, ovoid, green or yellow, 45 cm long, 35 cm in diameter.
- Seeds: Ovoid, 30–35 mm long, 25–30 mm wide, sarcotesta red.
Cultivation and Propagation: As a garden subject, Encephalartos whitelockii is one of the most spectacular of all cycad species. The seedlings grow rapidly, developing into an attractive garden plant with 3 ft (1 m) long leaves in four to five years. This is one of the fastest growing cycads and responds well to cultivation provided it has a well-drained soil, frost-free conditions and regular watering during the dry months. It is an adaptable plant well suited to subtropical climates. It can be grown in full sun without its leaves burning. When young they can be grown as a container plant and eventually transplanted into the garden. As a garden plant, this cycad will usually hold two or three crowns of leaves, all in good condition.
Growing rate: It is a very vigorous grower. Needs a large garden due to its size.
Soils: It prefer well drained, gritty soil with plenty of water, especially in dry weather.
Transplanting: This species transplants easily as a mature plant, although it is recommended to remove all of the leaves before doing so. This makes for easier handling and the plant will recover sooner due to less moisture loss.
Watering’s: In cultivation prefers moist soil with good drainage for optimal growth. But it is eventually drought resistant. Irrigation systems can be detrimental to cycads, damaging the leaves and stems from the pressure of the water as well as over-watering.
Fertilization: Naturally undemanding for nutrients, it responds very well to regular applications of fertilizer. Growth can be greatly improved through the application of fertilizers. Most growers find that a fertilizer having an even NPK (Nitrogen, Phosphorus, Potassium) balance, and supplemental trace elements, provides a good start for cycads.
Exposure: It thrives and grows best in full sun or partial shade.
Wind tolerance: It prefers a sheltered position providing protection from the prevailing winds.
Hardiness: Frost sensitive (USDA zones 10-12) .
Propagation: It may be propagated by seeds. They are among the easiest plants to germinate.