• AGM plants

    AGM plants have been through a rigorous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases

Astrophytum capricorne

goat's horn cactus

AGM plants

AGM plants have been through a rigorous trial and assessment programme. They are:

  • Excellent for ordinary use in appropriate conditions
  • Available to buy
  • Of good constitution
  • Essentially stable in form & colour
  • Reasonably resistant to pests & diseases
goat's horn cactus

© RHS

  • Other common names goat's horn cactus

  • Family Cactaceae

  • Genus Astrophytum are compact perennial cacti with ribbed, spherical or columnar stems bearing woolly, sometimes also shortly spiny areoles, and large, solitary, funnel-shaped flowers in summer, followed by red or green berries

  • Details A. capricorne is a spherical to ovoid cactus 20-25cm in height and 10cm in diameter, with 7-9 ribs which are light-green with white flecks. Long, twisted spines are yellowish-brown in colour. Yellow flowers 6-10cm are produced in summer

Characteristics

  • Foliage Evergreen

  • Habit Columnar/Upright

  • Hardiness

    Hardiness ratings

    All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

    • H1a - Under glass all year (>15C)
    • H1b - Can be grown outside in the summer (10 - 15)
    • H1c - Can be grown outside in the summer (5 - 10)
    • H2 - Tolerant of low temperatures, but not surviving being frozen (1 to 5)
    • H3 - Hardy in coastal and relatively mild parts of the UK (-5 to 1)
    • H4 - Hardy through most of the UK (-10 to -5)
    • H5 - Hardy in most places throughout the UK even in severe winters (-15 to -10)
    • H6 - Hardy in all of UK and northern Europe (-20 to -15)
    • H7 - Hardy in the severest European continental climates (< -20)

    H2

Colour

Sunlight

  • Full Sun

  • Aspect South-facing or West-facing

  • Exposure Sheltered

Soil

  • Loam

    Loam

  • Sand

    Sand

  • MoistureWell-drained

  • SoilLoam, Sand

  • pHAlkaline, Neutral, Acid

Size

  • Ultimate height 0.1-0.5 metres

  • Ultimate spread 0-0.1 metre

  • Time to ultimate height 10-20 years

How to grow

Cultivation Under glass grow in a sharply-draining loam based compost (JI No2) with extra perlite or sharp sand or a proprietary cactus compost, in bright filtered light. Water thoroughly once the compost has become dry in the growing season from spring to early-autumn, but keep dry when dormant. In warmer climates outdoors grow in sharply drained, poor, slightly alkaline soil in full sun

Propagation Propagate by seed sown at 21°C in early spring

Suggested planting locations and garden types Patio & Container Plants Sub-tropical

How to care

Pruning No pruning required

Pests scale insect and mealybugs may be a problem under glass

Diseases Generally disease free

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