Asplenium antiquum ‘Osaka’

Origin of Asplenium antiquum ‘Osaka’

‘Osaka’ is a cultivated bird’s-nest fern selection sold under Asplenium antiquum. The species is native to subtropical East Asia, including south-eastern China, Japan, Korea, the Nansei Islands and Taiwan.

Growing Asplenium antiquum ‘Osaka’ indoors

• Light: Give ‘Osaka’ bright indirect light or light shade.
• Temperature and humidity: Maintain roughly 16–25 °C. If the temperature approaches 15 °C, move it into a warmer part of the room. A 60–80% humidity range suits it.
• Watering: Water thoroughly when the top layer starts to dry, pouring around the rosette and letting the pot drain fully.
• Centre: Keep the rosette centre clear. Pour around it so moisture on the crown can dry between waterings.
• Potting mix: Use a loose fern mix with organic matter and coarse grit or perlite.
• Feeding: While the centre is producing fresh fronds, give a half-strength liquid feed about once a month.
• Cleaning: Support a frond from underneath and wipe dust away gently with a soft damp cloth.
• Slower growth: If the centre produces fewer fronds in dimmer conditions, allow more time between waterings, still watering when the upper layer starts to dry. Pause feeding until fresh fronds return.
• Repotting: When the root ball fills the container, increase pot size only a little. Replace dense, slow-draining mix without increasing pot size when roots still have room.
• Propagation: You can grow new plants from spores in warm, humid conditions.

When Asplenium antiquum ‘Osaka’ starts to decline

• Ruffled edges becoming brown: Dry air, mineral-rich water or uneven watering can brown the ruffled edges. Water more evenly, raise humidity if the air is dry and use softer water if mineral deposits build up on the mix.
• Repeatedly undersized or distorted new fronds: Low light, uneven watering or damage in the centre can distort new fronds. Check these conditions, correct any problem you find and watch how the next frond develops.
• Fixed bumps or sticky residue in the folds: Scale may be present. Examine the wavy edges, central veins and centre closely, then isolate the fern and apply a product labelled for scale on ornamental ferns. Repeat as directed on the label.
• A soft centre: Repeated wetting of the centre can lead to rot. Cut away all soft tissue with a disinfected tool until firm healthy growth is visible. Throw away the removed decay, disinfect the tool again and direct later waterings around the outside of the rosette.
• Roots turning dark and soft: Slow drainage and persistently damp mix can lead to root decay. With disinfected scissors, trim decay back to firm healthy tissue, discard the removed roots, clean the scissors again and repot in fresh free-draining mix.

If the problem returns on later fronds, reach out and we can work through the likely cause.

Asplenium antiquum ‘Osaka’ is non-toxic to cats and dogs

• This plant is non-toxic to cats and dogs.
• Its effects on people are unclear, so keep it away from young children who may chew it.
• Eating a large amount can still cause an upset stomach. Seek medical or veterinary advice if symptoms continue.

Where does the name Asplenium antiquum come from?

Asplenium comes from the old Greek name asplenon, linked with splen, spleen. The Latin epithet antiquum means old or ancient.

Carl Linnaeus established the genus Asplenium in 1753 in Species Plantarum, page 1078.

Tomitarô Makino first described Asplenium antiquum in 1929 in Journal of Japanese Botany, volume 6, page 32.