How often should I water Adiantum raddianum?

Keep the soil consistently moist but not waterlogged; water when the top inch of soil feels dry.

What kind of light does it need?

Bright, indirect light is ideal; avoid direct sunlight, which can scorch the fronds.

How can I increase humidity for my fern?

Mist the fronds regularly, place the pot on a pebble tray with water, or grow it in a terrarium.

Why are my fern's fronds turning brown and crispy?

This is usually due to low humidity, inconsistent watering, or direct sunlight.

Can I fertilize this fern?

Yes, feed with a balanced liquid fertilizer diluted to half strength every 4-6 weeks during the growing season.

Plant guide

Maidenhair Fern.

Adiantum raddianum

Pronounced AY-dee-an-tum RAD-ee-an-um

Also known as Delta Maidenhair, Delta Maidenhair-fern, Delta maidenhair fern, Fine Maidenhair Fern

The Fringed Maidenhair Fern is a delicate and beautiful fern, known for its lacy, fan-shaped fronds. It brings a touch of the tropics to any indoor space with its graceful appearance. This fern thrives in humid environments and prefers consistent moisture.

At a glance

Care level: Moderate
Plant type: Perennial fern
Light: Bright indirect light to partial shade
Indoor light: medium
Water: Every 2 to 4 days
Mature size: 1 to 2 feet tall and wide
Growth rate: medium
Hardiness: USDA 10 to 12
Bloom time: Not applicable (fern)

Care

Keep the soil consistently moist but not waterlogged, and provide high humidity to mimic its natural habitat. Avoid direct sunlight, which can scorch its delicate fronds. Good air circulation is also important to prevent fungal issues.

Watering: Water when the top inch of soil feels dry, ensuring the pot drains well.
Feeding: Feed with a balanced liquid fertilizer diluted to half strength every 4 weeks during the growing season.
Pruning: Remove any dead or damaged fronds at the base as needed to maintain appearance.
Repotting: Repot every 1 to 2 years in spring when the plant becomes root-bound.
Soil: Rich, well-draining potting mix with organic matter
Soil pH: 4.5 to 5.5
Temperature: 18 to 24°C
Humidity: 60 to 80%
Drought tolerance: low
Lifespan: Perennial
Deer and rabbits: moderate

Signs it needs repotting

Roots are growing out of the drainage holes.
The plant dries out very quickly after watering.
Growth appears stunted or slowed.
The soil seems to be breaking down or compacting excessively.

Safety

People: This plant is not known to be toxic to humans.
Pets: Non-toxic to cats and dogs.
Children: The delicate fronds pose no significant risk to children, but ingestion is not advised.
Edibility: This plant is not intended for consumption.

How to identify it

Triangular fronds
Delicate, fan-shaped leaflets
Black, wiry stems
Finely toothed leaflet edges
Spore-producing structures on leaflet undersides

Height: 0.3 to 0.6m
Spread: 0.3 to 0.6m
Leaves: Green, evergreen

Common problems

Spider Mites — Tiny pests that thrive in dry conditions, causing stippling on fronds and fine webbing.
Bacterial Leaf Spot — Causes water-soaked spots on fronds that enlarge and may have a yellow halo.
Fungal Leaf Spot — Appears as small, circular spots on the fronds, which can be brown or black.
Frizzle Top — Fronds become stunted, distorted, and brown, often due to inconsistent watering or low humidity.

Growing it

Propagation: Division, Spores
When to plant: Spring, Summer
Overwintering: Indoors, maintain consistent moisture and humidity. Avoid placing near heat vents or drafty windows. Reduce fertilizer slightly during winter months if growth slows.
In containers: Grows very well in pots, especially hanging baskets or terrariums, as it helps maintain humidity. A pot at least 6 inches in diameter is recommended.

Division

Gently remove the fern from its pot.
Carefully tease apart the root ball into sections, ensuring each section has healthy roots and fronds.
Repot each section into its own container with fresh potting mix.
Water thoroughly and keep in a humid environment until established.

Spores

Collect ripe spores from the underside of mature fronds.
Sow spores thinly on the surface of a moist, sterile propagation medium in a closed container.
Keep in a warm, dimly lit location and maintain high humidity.
Prick out the young prothalli (small, heart-shaped structures) into a suitable potting mix once they develop.
Grow on in a humid environment until the ferns are large enough to handle.

Pair this fern with other moisture-loving, shade-tolerant plants to create a lush, humid microclimate.

Grows well with

Orchids — Orchids often share similar humidity and light requirements, creating a harmonious display in terrariums or shaded gardens.
Peperomia — Peperomias generally prefer moderate to high humidity and indirect light, making them good companions for maidenhair ferns.
Fittonia — Nerve plants thrive in high humidity and low light, conditions that also suit Adiantum raddianum.
Selaginella — Spikemosses often require similar moist, shaded conditions and can complement the delicate texture of maidenhair ferns.

Keep away from

Cacti — Cacti require dry conditions and direct sunlight, which are detrimental to the moisture and shade-loving maidenhair fern.
Succulents — Most succulents prefer well-draining soil and less humidity than Adiantum raddianum needs to thrive.

Similar species

Delta Maidenhair Fern — Similar in its need for high humidity and indirect light, but typically has broader, more angular fronds.
Southern Maidenhair Fern — Another delicate fern that prefers moist, shaded conditions, though it may have finer leaflets.
Blackstem Maidenhair Fern — Shares the need for consistent moisture and shade, but often has a more upright growth habit and darker stems.

Science

Family: Pteridaceae
Genus: Adiantum
Order: Polypodiales
Class: Polypodiopsida
Native range: Tropical Americas
Conservation: This species is not currently considered of conservation concern.

In its native habitat, this fern thrives in moist, shaded areas, often found on rocks or in the crotches of trees.

Uses: Ornamental

Through the year

JFMAMJJASOND

Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 1/9
Soil reaction: 6/9
Light: 3/9
Temperature: 7/9
Moisture: 7/9
Nutrients: 4/9

Taxonomy resolved against GBIF.

Questions people ask

How often should I water Adiantum raddianum?: Keep the soil consistently moist but not waterlogged; water when the top inch of soil feels dry.
What kind of light does it need?: Bright, indirect light is ideal; avoid direct sunlight, which can scorch the fronds.
How can I increase humidity for my fern?: Mist the fronds regularly, place the pot on a pebble tray with water, or grow it in a terrarium.
Why are my fern's fronds turning brown and crispy?: This is usually due to low humidity, inconsistent watering, or direct sunlight.
Can I fertilize this fern?: Yes, feed with a balanced liquid fertilizer diluted to half strength every 4-6 weeks during the growing season.

Where the name comes from

The genus name 'Adiantum' comes from the Greek words 'a' (not) and 'diaino' (to wet), referring to the water-repellent nature of its leaves. 'Raddianum' honors the Italian botanist Giuseppe Raddi.

Good to know

Maidenhair ferns are ancient plants, with ancestors dating back millions of years.
They prefer humid environments and can be sensitive to dry air.
The name 'Adiantum' comes from the Greek word for 'unwetted', referring to how water beads off the leaves.
This fern is a popular choice for terrariums and hanging baskets.

Is your maidenhair fern looking unwell?

This page is a general guide. Pocket Botanist diagnoses problems from a photo of your actual plant, works out watering for your light and conditions, and reminds you when care is due.

Get the app

This guide was generated with AI and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.