Dicksonia
Dicksonia antarctica
A tree fern drinks through its trunk — soak that, not just the ground, and keep the crown from sitting wet.
- Type
- Tree · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Green
- Sunlight
- Partial to deep shade; direct sun is to be avoided.
- Watering
- Water the trunk and crown regularly, keeping both consistently moist.
- Feeding
- A dilute liquid feed monthly through the growing season.
- Frost tolerant
- Yes
- Flowering
- June
- Pruning
- Cut dead fronds away; never pull them off.
- Overwintering
- Pack the crown with straw or frost cloth below -5°C, and clear it away in spring.
- Apr–Jun Spring Growth
- Jun–Oct Flowering
- Oct–Dec Growing
- Dec–Dec Leaf Fall
- Jan–Apr Leaf Fall
- Plant spacing
- 8 ft 2 in
- In-row spacing
- 8 ft 2 in
- Between rows
- 10 ft 3 in
- Square-foot density
- Not suited to SFG
- Root system
- A creeping rhizome with wiry black roots
- Working depth
- 4–12 in
- Can reach
- 18 in down where the soil allows
- Spread
- 8–16 ft across, about 1–2× the width of the plant
- Shallowest pot
- 8 in of soil
The rhizome runs at the surface under leaf litter, which is exactly where a fern wants it: covered, damp and never disturbed. Bury it in soil and it rots, leave it bare and it dries, so leaf mould over the top is the whole of its cultivation.
The trunk of a tree fern is not wood, it is a column of matted roots around a slender stem, and it takes up water along its whole height. That is why a tree fern is watered into the top of the trunk rather than at the ground, and why a transplanted one with the trunk sawn short still lives.
The habit is Dicksonia’s own; the figures are what that habit usually comes to at this size, not a measurement of this species. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
- Root & crown rot Crown rot from waterlogging — see that water drains away from the growing point
- Drought stress The trunk drying out in a dry spell — water the trunk, not only the soil
- Wind tearing the fronds — give it a sheltered position
- Hard frost killing the growing point — cover it below -5°C
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com