Encephalartos horridus
Encephalartos horridus
Eastern Cape Blue Cycad
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Taxonomy
Family Zamiaceae · Genus Encephalartos
Description
Encephalartos horridus is a striking blue cycad from South Africa, loved for its powdery steel-blue, fiercely spined fronds and sculptural form. Extremely slow-growing and drought-tolerant, it thrives in bright sun and makes a dramatic focal point in xeric gardens or containers.
Common Names
Eastern Cape Blue CycadHorridus CycadBlue CycadHorrid Cycad
Context
nativeRegion
Eastern Cape Province, South Africa (arid thicket and karoo scrub).
usdaZones
9b–11
companionPlants
Aloe species, Agave species, Portulacaria afra, Euphorbia tirucalli, Senecio mandraliscae, Bulbine frutescens
culturalUses
Highly prized ornamental and collector’s cycad; used in xeriscapes and architectural plantings. Noted conservation significance as a threatened species.
Care
Care Requirements
LightFull sun for best blue color; light afternoon shade in very hot interiors or for young plants.
WateringInfrequent, deep watering; allow soil to dry thoroughly between waterings. Reduce markedly in cool weather.
SoilExceptionally well-drained, gritty mix (sandy/rocky, mineral-heavy). Slightly acidic to slightly alkaline.
FertilizerLight feeding in spring–summer with slow-release, low-nitrogen or cycad/palm fertilizer plus micronutrients; avoid overfertilizing.
HumidityLow to moderate; tolerates arid conditions well.
TemperatureIdeal 60–90°F (15–32°C). Brief dips to ~25°F (-4°C) if dry; protect from hard/prolonged freezes.
Growth & Life Cycle
HabitTrunk-forming cycad with a tight crown of stiff, spiny, blue-gray fronds; often clumping with age.
Mature SizeTrunk 1–3 ft (0.3–1 m) tall, 8–16 in (20–40 cm) diameter; fronds 2–4 ft (0.6–1.2 m) long; crown to ~4–6 ft (1.2–1.8 m) across.
Growth RateVery slow-growing.
BloomingDioecious; males and females produce cones, typically late spring to summer. Insect or hand-pollinated.
DormancyNo true dormancy; growth slows in cool months, with leaf flushes in warm seasons.
Propagation
MethodsSeed, Offsets/Suckers
DifficultyModerate to difficult (seed requires warmth and patience; offsets slow to root).
Best SeasonLate spring to summer for sowing seed and establishing offsets.
Maintenance & Notes
PruningRemove spent fronds and cones in late winter or early spring; handle carefully due to sharp spines.
RepottingRepot container specimens every 3–5 years or when rootbound, using a heavy, fast-draining mineral mix.
Pests & DiseasesScale (incl. cycad aulacaspis), mealybugs, spider mites; root/crown rot from overwatering; snails may chew fronds.
ToxicityAll parts toxic if ingested (cycasin), especially seeds; keep away from pets and children.
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