This Spleenwort is a relatively recent addition to the houseplant range: it is a more compact and narrower-leaved plant than the closely-related Bird’s Nest Fern, which makes Asplenium antiguum a better plant for use in a terrarium or bottle garden, or where space is at a premium. Japanese in origin, Asplenium antiguum has rich green leaves which emerge from a central growing point and are floppy when compared to those of the Bird’s Nest Fern. The outer leaves gradually die off and are replaced by new leaves from the centre; keep the plant tidy by clearing away the old foliage once it can be gently pulled off. This is very important in the contained environment of a bottle garden or terrarium, where decaying foliage encourages fungal disease.
This plant is able to withstand a minimum temperature of 10°C (50°F), and will grow well at a range of 15-22°C (59-72°F); higher temperatures are only acceptable if the humidity and moisture levels are also increased.
Position this Fern out of direct sunlight: the light from a North-facing window will be best. If A. antiguum is grown in a terrarium or bottle garden, ensure that the glass is kept clean.
Water this plant well during the growing season, keeping themoist without overdoing it. Give less water from late Autumn to early Spring, but adjust according to growing conditions.
This Japanese species will benefit from a high level of humidity, although this is less important if temperatures are low. Mist regularly or stand it on a bed of moisture-retentive pellets.
Feed established plants every six months with a foliage houseplant feed, diluted to half strength.
Repot overcrowded plants in Spring, using a peat-based compost; a 2cm (3/4in) layer of crushed charcoal at the base of the pot will prevent the compost from going sour and is essential in bottle gardens and terraria. Plants in closed environments must be monitored closely in the early stages, as the microclimate must be in balance: the inside of the glass must be clear of condensation, and the plants well moistened before the top is closed. If you have difficulty in achieving the correct balance, use cling film as a temporary measure – it is easier to adjust than a cork or lid. Once the balance seems right, replace the cling film with the proper top.
Chemical attack: Many Ferns are sensitive to insecticides, so use other methods first and insecticides last.
Scale should not be confused with regularly-spaced brown spores also found on the undersides of the fronds. Eradicate irregular brown dots of Scale with methylated spirit on a cotton wool bud; remove and burn badly-infested fronds.
Fronds: Very hot conditions will turn fronds yellow from the base, while crispy tips are due to dry air and lack of humidity; scorch marks form on the fronds when sunlight burns the plant.