Alsophila australis

RHS Plant Profile
Australian tree fern

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Australian tree fern RHS

Other common names

hill tree-fern, rough tree fern

Synonyms

Cyathea australis

Conservatory Greenhouse Ferns
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A tree fern with a terminal cluster of spreading fronds on a stem clothed with persistent frond bases that are covered with brown scales

Position

Partial shade

Soil Types

Loam, Sand

Max Height

2.5-4 metres

Max Spread

2.5-4 metres

Size

Time to Maturity
20–50 years
Max Spread
2.5-4 metres
Max Height
2.5-4 metres

Growing Conditions

Loam Sand
Moisture
Moist but well–drained
pH
Acid or Neutral

Position

Partial shade
Aspect
South–facing or East–facing or West–facing
Exposure
Sheltered
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 & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Cyatheaceae
Native to GB/Ireland
No
Foliage
Evergreen
Habit
Bushy
Genus
A genus of tree ferns, native to the tropics and subtropics, with upright stems and large, dark green fronds on top of the stems
Name Status
Correct
Plant Range
Eastern Australia

How to Grow

Cultivation

In areas prone to frost, grow in a container under glass with a minimum winter temperature of 10°C (50F). The plant may be placed outside during the summer in a sheltered and partially shaded spot. It requires a moist but well-drained humus-rich soil; in hot, dry summers water the stem as well as the soil, but avoid watering the crown in winter. Apply liquid fertiliser monthly during the growing season. Will grow without winter protection only in milder areas. See tree fern cultivation for further advice

Propagation

Propagate by sowing spores as soon as ripe

Suggested planting locations and garden types

  • City and courtyard gardens
  • Coastal
  • Cottage and informal garden
  • Architectural
  • Flower borders and beds

Pruning

Dead or damaged fronds may be removed as necessary

Pests

Generally pest-free outdoors

Diseases

Generally disease-free