The glossy, deep green leaves of leatherleaf ferns blend effortlessly into many garden themes

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Rumohra adiantiformis Picture courtesy Forest and Kim Starr - Click on the picture to see their flickr pageRumohra adiantiformis Picture courtesy Forest and Kim Starr - Click on the picture to see their flickr pageThe lush-looking leatherleaf fern is easy to grow in those semi shaded or moist areas of the garden, and it grows well in both coastal and cold inland gardens. It also makes a good indoor plant. Read more below on how to use it in the garden and how to grow and care for this lovely indigenous fern.

Gardeners love leatherleaf ferns for their beautiful leaves, their hardiness and ease of growth, as well as their versatility in the garden. Their large and leathery, deep green leaves blend effortlessly into so many garden themes, and make an excellent permanent ground cover for those moist and semi-shady areas. Their fronds are sought-after by florists, and the common name "seven-week fern" refers to how long they can last when cut. Read more on planting and caring for these ferns below.

The leatherleaf fern belongs to the (Dryopteridaceae) or wood fern family which is very diverse, with approximately 570 species worldwide. They have a wide distribution in tropical and sub-tropical regions of both the old and the new world, including South Africa and diverse places like Colombia, The Galapagos Islands, Australia and New Zealand. The greatest numbers of species are found in southern, south-eastern, and eastern Asia.

In South Africa only a few species occur, from the Cape Peninsula eastwards along the southern side of the mountain ranges all the way to the Eastern Cape, and into KwaZulu-Natal, east of the Drakensberg, and into Mpumalanga and Limpopo, to the Soutpansberg mountains. Species occur from sea level, up to approximately 3,000m in the Drakensberg.

The wood fern family are mostly forest dwellers, forming colonies of plants which thrive in the dappled shade and leaf litter of the moist forest floor. They can also be found growing on rocks, but rarely in trees as epiphytes, and at higher altitudes they are often found colonising sheltered rock crevices.

Rumohra adiantiformis growing in the shelter of rocks. Picture courtesy Clivid - Click on the picture to see the flickr pageRumohra adiantiformis growing in the shelter of rocks. Picture courtesy Clivid - Click on the picture to see the flickr pageThey also favour permanently moist, or seasonally moist habitats, with some species being restricted to the summer rainfall regions of South Africa, and others occurring in both the summer and winter rainfall regions. Other species can be found in sheltered positions in open grasslands, for example, in  sinkholes and along drainage lines, or at the base of boulders, which all offer some protection and shade. They spread by underground rhizomes, and these protect the plants from fires, and once a fire has swept through the area, they quickly regenerate after rain.

The leatherleaf (Rumohra adiantiformis) is native to South America, the Caribbean, southern Africa, the Western Indian Ocean islands, Papua New Guinea, and Australasia. Countries it is native to include such diverse places as Brazil and Colombia, the Galápagos Islands, the Greater Antilles in the Caribbean, Zimbabwe and South Africa, Australia, and New Zealand.

The leather leaf fern is widely grown in South African gardens and can vary significantly in size, depending on climate and rainfall, for example, in moist tropical and sub-tropical regions it can attain heights of 75cm to 1.5m with a 1m spread, but in cold and dry inland gardens, or on exposed coastal sites, the plants will remain a lot smaller. The plant can take 2 to 5 years to reach its ultimate height and spread, so generally leather leaf ferns are sold as growing 50 to 60cm tall, with a 40 to 50cm spread.

Other South African members of the Dryopteridaceae which are recommended as garden subjects include Cyrtomium micropterum, and Polystichum luctuosum, P. macleae, P. monticola, P. pungens, P. transvaalense and P. wilsonii.

Find more information on these indigenous beauties – click on the names to read more at PlantZAfrica and Fernkloof.org.za

In the Garden & Home:

Gardeners love leatherleaf ferns for their beautiful evergreen leaves, ease of growth, and versatility in the garden, and in the UK the leatherleaf has gained the Royal Horticultural Society’s Award of Garden Merit.

Their glossy and coarsely toothed deep-green fronds make an excellent permanent ground cover for shady beds, underneath evergreen trees and palms, or shrubs like camellias, coprosma, hydrangeas and gardenias.

Leather leaf ferns will add texture and contrast to formal or informal gardens and are attractive filler plants. For a modern look, try combining them with ornamental grasses like carex, complimented by nandina, black bamboo and New Zealand flax.

Because leatherleaf ferns thrive near water, they are ideal for accentuating water features which are sited where there is semi-shade. They also work well as a cover-up for slab foundations or underneath low windows and overhead shade structures.

This plant spreads slowly, which works nicely for small spaces or in a hanging basket. This also makes them perfect to grow in atriums and low, broad pots with a wide diameter which allows them space to spread.

Leatherleaf ferns also make great indoor pot plants if they can be placed in a cool, yet brightly lit spot indoors, and if the leaves and topsoil are mist sprayed regularly with water. Pot and feed as for those growing outdoors. 

The fronds are sought after by florists around the world because they will last for weeks in a vase, making the leather leaf essential for all cutting and cottage gardens.

Cultivation/Propagation:

These evergreen perennials spread by rhizomes and although they thrive in tropical and subtropical gardens, in South Africa they are also frost and cold hardy if planted in a protected part of the garden. In severely cold regions the plant will require some protection during the winter months.

The leatherleaf fern can take more sun in coastal gardens than it does inland, and although it tolerates salt spray, it looks much better if planted in a wind protected part of the garden. Once the plants are established they can be somewhat drought tolerant, especially in conditions with high humidity.

Ferns always look at their best when grown in indirect light like the cool shady areas underneath trees, where they will receive semi-shade to partial sun for short periods of the day. Leatherleaf ferns will even grow in complete shade, but growth may be less vigorous. Avoid positions where they will receive really deep, dark shade, as well as those which get too much sun, or harsh afternoon sun. 

To establish a deep, extensive root system, prepare the beds well by digging them over well to a depth of about 30cm and incorporate lots of organic matter like leaf mould and compost, palm peat, and even fine bark chips, together with a generous dusting of bone meal.  Ensure that the soil drains well, because although ferns love moist soils they do not like to be waterlogged. Ferns also generally prefer slightly acid soils, so the addition of acid compost or an acidic potting medium is recommended.

Potted plants do well in commercially sold orchid mix, or potting soil mixed with palm peat and the addition of extra perlite or grit for sharp drainage.  

Feed garden and potted specimens monthly in the growing period with a liquid fertiliser for leafy plants, mixed at half the recommended strength. A slow-release product may also be used. Remember to mulch your plants annually with bark chips, leaf mould, or any good organic material, as this helps to keep the soil cool and moist.

Follow a regular watering schedule until the plants are established, and thereafter they will only need moderate watering during dry spells, as the leatherleaf is not as thirsty as many other ferns. In seasonally dry regions the plants will die down if they are not watered, only to spring back to life again with the onset of the next rainy season. To look their best in the garden, never let your leatherleaf fern go completely dry, and try to keep it moist but not waterlogged.

Cut back old tatty-looking fronds regularly to keep your clump of leatherleaf looking good all year round. 

Some species have rhizomes which are close to the ground and multiply readily by branching, and these are best propagated by division. Other species have sub-erect or erect rhizomes and are propagated by spores, as offshoots are not readily produced.

Problems, Pests & Diseases:

If grown correctly the leatherleaf is not prone to many pests or diseases. Watch out for common garden pests like caterpillars and the occasional snail or slug. Scale and mealy bugs can become a problem on plants grown indoors or in a covered area like a patio, but are easily treated.

Ferns are sensitive to some pesticides, so consult with your garden centre on the best product to use and how strong to make the mixture.

Warning:

We did not find this fern listed as toxic to pets, but it is always wise to discourage pets from chewing on plants, and to supervise babies and small children around plants.