Cape aloe

Sun

Full sun; introduce plants grown under cover to strong outdoor sun gradually.

Water

Low once established. Water deeply during active growth, then let the soil dry; keep much drier in cool weather.

Soil

Very free-draining sandy or gravelly soil. In containers, use a gritty cactus and succulent mix and a pot with drainage holes.

Height

6-10 ft (1.8-3 m)

Spread

3-5 ft (0.9-1.5 m)

Flowers

Usually winter into spring, with timing varying by climate; branched flower stalks carry dense spikes of tubular orange-red flowers, occasionally yellow.

Foliage

Evergreen. Thick, blue-green to dull green leaves form a large rosette. Reddish-brown teeth line the margins; young plants often also have prickles on the leaf surfaces. Dead leaves commonly remain as a skirt around the trunk.

Growth

Slow

Care needed

Low

• Pollinators
• Deer resistant
• Drought tolerant
• Heat tolerant
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   0.9 ft (0.29 m)

2. After 1 year

   1.7 ft (0.51 m)

3. After 2 years

   2.4 ft (0.73 m)

4. After 3 years

   3 ft (0.95 m)

5. After 5 years

   5 ft (1.4 m)

About 10 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Growth rate

Slow

• Plant on a raised mound or slope if drainage is uncertain; do not plant in a low spot that stays wet.
• Water newly planted specimens when the root zone has dried, then reduce watering once established.
• Keep water out of the crown during cold weather and empty container saucers after watering.
• Feed container plants lightly once in spring with a diluted cactus fertiliser; established plants in the ground seldom need feeding.
• Use gravel rather than moisture-holding mulch around the base, keeping the crown clear.
• Protect from frost and persistent winter rain; move containers under bright, frost-free cover in cold climates.

Pruning. Cut spent flower stalks near their base after flowering. Leave the natural skirt of dead leaves, or remove only fully dry leaves carefully; wear thick gloves and eye protection around the spines.

Spring

Plant or repot once frost risk has passed, using a very free-draining mix.

Late spring

Acclimatise overwintered container plants gradually to outdoor sunshine.

Summer

Water deeply only after the root zone dries, and check leaf bases for mealybugs.

Autumn

Reduce watering as temperatures fall and move containers into shelter before frost.

Winter

Keep sheltered plants bright and mostly dry; protect outdoor crowns from prolonged cold rain.

After flowering

Remove faded flower stalks without cutting into the leafy crown.

• Use as a single focal plant in a sunny gravel garden, with open space around its spiny crown.
• Combine with low-growing succulents and rounded rocks for contrasting shapes in a dry border.
• Grow in a large, stable container on a sunny terrace where winter shelter is available.
• Plant on a well-drained bank with other South African drought-tolerant plants for winter colour.

Garden styles it suits: Architectural minimal, Desert modern, Mediterranean, Desert / xeriscape, Dry gravel garden and Winter interest.

Plant it with: Blue chalksticks, Rock purslane, Ice plant, Red yucca, Lavender and Pincushion euphorbia.

Wildlife: Nectar-rich flowers attract sunbirds in its native range, and may attract hummingbirds where grown in the Americas. Bees also visit the flowers.

• Root or crown rot: prevent standing water, improve drainage and reduce winter watering; badly rotted crowns are usually beyond saving.
• Mealybugs and scale: inspect leaf bases regularly, remove small infestations by hand and use a labelled treatment if they persist.
• Aloe gall mite: distorted, knobbly growth can indicate mites; isolate affected plants, remove affected tissue and seek local treatment advice. Discard severely affected plants.
• Frost damage: leaves become soft or blackened after freezing; provide winter shelter and wait until spring to remove clearly dead tissue.

Do not eat the leaves or use them for home remedies. The yellow latex beneath the leaf skin contains strong laxative compounds and can cause abdominal pain, diarrhoea and dehydration in people. Treat the leaves as toxic to cats, dogs and horses if eaten. The sharp leaf teeth can also injure people and animals.

• Mountain aloe (Aloe marlothii)

  Usually has more conspicuous prickles across the leaf surfaces and a broad flower head with spreading, often nearly horizontal branches; Cape aloe generally has more upright flower spikes.

• Krantz aloe (Aloe arborescens)

  Forms a branching, many-headed shrub with narrower leaves, rather than the usually single trunk and large crown of Cape aloe.

• Aloe vera (Aloe vera)

  Usually forms low, offsetting clumps with little visible trunk and commonly yellow flowers; Cape aloe develops a tall trunk and a large crown with mostly orange-red flowers.

Cape refers to its South African origin, while the Latin ferox means fierce, referring to its formidable leaf spines.

Propagation. Usually grown from seed sown in spring in a warm, bright place using a free-draining seed mix. Keep lightly moist, not wet, until established. It rarely produces offsets, so division is not a dependable method.

Accepted botanical name

Aloe ferox

Native range

Cape Provinces, Free State and Lesotho.

Sources: GBIF (CC BY 4.0) and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.