Also Known As: Coast Aloe, Dune Aloe
Category: Single Head Tree Aloes
USDA Hardiness Zones: 9b - 11
OverviewAloe thraskii is wonderful feature plant that is tall and robust, with enormous olive green leaves that are recurved back to the trunk, sometimes even touching the skirt of old, dried leaves around the trunk. This unbranched tree-like Aloe grows to 10 feet with deeply concave (U-shaped in cross section) pale olive-green leaves that have small reddish-brown marginal teeth. Also known as the Dune Aloe this fast-growing, South African, un-branched succulent plant, develops a very large and beautiful rosette.
DescriptionIt is among the tallest aloe species usually about 2 meters tall, Aloe thraskii can reach up to 4 meters with a width of up to two meters. The long, pale, grey-green leaves are deeply grooved or channeled and recurve downwards. Has typical arching, grooved aloe leaves with light green coloration. The long leaves curve strongly downwards, with the tips of the lower leaves touching the stem. Leaves are up to roughly 5ft (160 cm) long and 8inches (22 cm wide), broadly lanceolate, glaucous, sometimes with a few spines on both the upper and lower surfaces. The shaggy remains of old leaves cloak the trunk. Stems are single, robust and usually 2 meters in height but can reach up to 4 meters in older specimens. Spines are sometimes also present in a line down the middle of the lower leaf surface. Margins armed with reddish-brown teeth maturing from initial white teeth on young leaves.
FloweringIn winter the orange and yellow flowers grow in short, compact, cylindrical racemes, on multi-branched inflorescences. Younger plants may only produce a single inflorescences while older ones can produce 3 to 4 inflorescences with 15 to 25 upright broadly-cylindrical erect racemes. Flowers are quite small and yellow in color, the flowers mouth tips are tinged green, stamens protrude from the flowers mouth and are orange in color. The flowers are yellow, with green tinged tips, and the anthers are orange, giving the flowers a bicolored look.
Origin / HistoryThis plant comes from sand dunes along the east coast of South Africa and is best grown in coastal areas. These plants are naturally found along the coast in a very narrow strip, never more than a few hundred metres from the sea. They are always found in groups in the coastal thicket, often as part of the ground layer or sometime in clearings and rocky places. This South African native named by John Gilbert Baker (1834-1920) in 1880 was named for a Mr Thrask, of whom nothing beside his name is known. Aloe thraskii is classed as Near Threatened in its natural habitat due to habitat loss from urban and coastal development and illegal collecting for the specialist succulent horticultural trade. It can also be confused with Aloe vanballenii when young, and Aloes angelica and Aloes alooides as mature plant. It has been given tree status in South Africa.
Care / CultivationThe Dune aloe grows fast in cultivation and is especially suited for coastal situations as it tolerates wind and salt air. It can be grown in inland gardens with mild winters and not overly damp summers. Aloe thraskii grows well in cultivation, where it has proven to be very fast growing, developing a 'trunk' early in life. They are really not very demanding and regular watering in their growing season creates healthy disease resistant plants that will flower better. It should be watered sparingly in the garden and provided with very good ventilation. Nearly all problems occur as a result of overwatering and poor ventilation, especially when weather conditions are dull and cool or very humid. Plant it in full sun and ensure that the soil drains very well, to help prevent fungal infections. During the winter months, the plants should be grown cool to initiate flower development (about 10°C ). Feed it during the growing season with a fertilizer specifically formulated for cactus and succulents (high potash fertilizer with a dilute low nitrogen), including all micro nutrients and trace elements diluted to ½ the strength recommended on the label. Will handle very harsh sunlight, sometimes taking on a coppery leaf sheen, a sign generally associated with stress. Occasionally these plants are infested by scale and aphids, but all known garden pests can be kept to a minimum by simply ensuring optimal growing conditions and healthy plants.
Frost TendernessThe dune aloe is tender to frost with cold tolerance to about 25F with some mild leaf damage at that temperature. Aloe thraskii flowers are more frost sensitive than the leaves.
Use in the GardenIdeal for planting on slopes, sandy or stony soil. As its name suggests, Coast Aloe is well suited to growing in coastal regions. Flowers attract many bees and birds. Outdoors it grows to astonishing proportions also in areas with wet winters, so don't be afraid to plant this in a high-rainfall area. It can be also cultivated outdoors in raised beds and terraces and is one of the aloes that can form a centre piece in a garden or grouped, creating a magnificent backdrop, if you have the space, to provide form and texture. This wonderful architectural plant will add accent and interest to your garden and will attract nectar and insect eating birds. Plant it as a single specimen or in large groups, for great effect. The dune aloe also grows beautifully in large containers.
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