ANNE SWITHINBANK’S MASTERCLASS
How to grow and care for your indoor ferns
QMy large and beautiful maidenhair fern is unwell, with yellow-brown fronds. There might be some tiny black flies on the fronds, but I don’t want to spray and risk harming the fern. What other indoor ferns do you recommend? Margaret Stoll, Brighton, East Sussex
AMaidenhair ferns make graceful indoor plants, usually represented by the Delta maidenhair fern (Adiantum raddianum) or the Venus hair fern
(A. capillus-veneris). While small, they are rather needy as the roots are prone to drying out, but once in pots 6-9in
(15-23cm) across, long-lived specimens can reach 12-24in (30-60cm) high and
30in (76cm) wide.
Examine the plant using a hand lens to reveal whether there is a pest present or if the fern just needs better nurturing. There is a specific fern aphid called Idiopterus nephrelepidis which, at a fraction of an inch (1.6mm) long, is barely visible to the naked eye. These are black with pale legs and, in the UK, usually only troublesome indoors.
With any infested plant, I aim to remove as much pest-carrying material as possible and in this case, I might cut all fronds down except the tiny new ones. Wellestablished ferns grow back readily, and I’ve had good results with maidenhairs and an Asplenium bulbiferum bothered by scale insects. What’s left of the plant is easier to spray with something like SB Plant Invigorator containing foliar lattice and iron chelate, which also acts as a growth stimulant.
To increase your collection, look out for the bird’s nest fern (Asplenium nidus), adapted to growing on trees in tropical forests. I’ve recently developed a passion for rhizomatous ferns with furry or scaly rhizomes that would cling to damp tree trunks and branches in the wild. The squirrel’s foot fern (Davallia mariesii) looks like a hairy-legged spider sitting on a pot, while the rhizomes of the hare’s foot fern
(D. canariensis) are chunky and slower to develop. Finally, the golden polypody (Phlebodium aureum) bears blue-green fronds and will reach 30in (76cm) high and 4ft (1.2m) wide.