How to grow and care for mermaid tail (fishtail fern)

What you need to know about mermaid tail

Name: mermaid tail, Microsorum punctatum; the variety ‘Grandiceps’ is one of the best.

Height: overall about 60cm high and similar width.

Foliage: strappy, mid-green, tough; single ‘blade’ that forks repeatedly to form a tasselled or crested tip.

Climate: tropical to temperate; tolerates light frost.

Soil: fertile loam that drains well.

Position: light, airy position; light shade preferred; sun tolerant.

Feeding: use a long-term controlled-release fertiliser applied sparingly.

Watering: water regularly; good drainage essential.

Appearance and characteristics of mermaid tail fern

Mermaid tail is an epiphyte—that is, it grows naturally on another plant or in the crevice of a rock, rather than sending roots down into the soil. Epiphytes can be parasitic (drawing nourishment and moisture from the host plant), or they might simply use their host plant as a support. Mermaid tail is not parasitic.

It may also grow at ground level in soil or leaf litter. Although it doesn’t have traditional roots, it does develop an underground horizontal stem, called a rhizome, by which it spreads by running along the ground.

The fronds of mermaid tail are blade-like and quite tough, like those of the staghorn, and mid-green. Each may be up to 60cm in height, dividing in two and then two again several times towards the tip, creating the crest or tassel by which this fern is often identified.

Mermaid tail does not flower. It reproduces by spores carried on the undersides of leaves in small brown spots.

How to plant and grow mermaid tail fern

• Mermaid tail fern may be grown epiphytically by encasing the rhizome in moistened sphagnum moss and then tying the plant securely to either a suitable rough-barked tree or a bark backing board, which can then be hung in a tree—tree fern bark is ideal if you can find it.
• Use commercial plant tie material or pantyhose to secure the fern in place, rather than a wire or fishing line, which could cut into the fern itself.
• Alternatively, mermaid tail can be grown quite successfully in the ground or in a pot.

In the garden

• Choose a warm position with good natural light and some shade (remember, mermaid tail grows naturally on trees and rocks in tropical areas, where the forest canopy protects it).
• Soil should be a rich loam that drains freely while still holding some moisture after rainfall or watering.
• The pH should be acidic—between 5.5 and 6.5.
• Work in a light application of long-term controlled-release fertiliser that’s low in phosphorus (P).
• As an epiphyte, mermaid tail should not be ‘buried’ in the soil—rather, its horizontal rhizome should be laid in a furrow no more than 10cm deep and then covered with soil or leaf litter compost.
• Plants should be spaced about 50–60cm apart.
• Water in well.

In a pot

• Mermaid tail prefers a wide pot that’s not too deep, so its horizontal rhizome has room to grow.
• A wire hanging planter with a coir fibre liner or hollowed-out section of tree fern trunk would also suit.
• Use a premium-quality native plant potting mix.
• Similarly to planting in the garden, don’t bury the fern’s rhizome.
• Water in well.
• Mermaid tail makes a great indoor plant in cool climates—mist the foliage regularly to maintain humidity.

Caring for mermaid tail fern

Watering

Mermaid tail enjoys very similar conditions to elkhorn and staghorn ferns. When attached to trees or backing boards, it should be watered regularly to keep the sphagnum moss around the rhizome moist—it also likes humidity, so wet the surrounding tree as well.

In the garden, keep the soil moist but not wet—good drainage is essential. The same applies to pots or hanging planters—water regularly and ensure excess drains away freely.

Fertilising

Feed mermaid tail monthly with a water-soluble or liquid plant food suitable for native plants (low phosphorus, P).

A long-term, low P controlled-release fertiliser can also be applied sparingly once a year.

Diseases and pests

Like many other ferns, mermaid tail may be attacked by aphids, scale and mealy bugs. The best way to eradicate them is physical removal, but if that’s not possible, use a horticultural oil. Read the instructions to see what strength you should use on ferns.

How to propagate mermaid tail fern

• Mermaid tail can be raised from spores, but this is not usually practical for home gardeners because the process requires specialist equipment and conditions. If you have a glasshouse where warmth and humidity can be maintained, you may have some success.
• The simplest way to increase plant numbers is by dividing existing plants.
• Rhizome cuttings can also be taken, but these may take longer to grow than sections taken from older plants.

If you like this then try

Frangipani: a stunning plant bringing the fragrance of the tropics that provides shade to under-storey ferns; epiphytes can be grown in forks of branches.

Poinciana: also known as flame tree, poinciana thrives in tropical and sub-tropical areas, producing fern-like leaves and masses of orange-red flowers.

Mandevilla: a fast-growing, free-flowering climbing vine often associated with tropical and sub-tropical gardens.

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