If you are tired of the same old common plants in your garden, why not try something different, maybe even specialize.
Ferns are a good example of a whole family of plants that are poorly represented in our gardens. It’s not that they can’t be grown, but that we don’t give them much of a try.
Ferns, in general, are free of insect and disease problems. They require very little fertilizer but do require moisture and shade from intense sunlight. Our cooler mauka areas and east side of the island are probably the best for growing ferns, but many types can be grown almost anywhere with protection.
We have hundreds of ferns native and introduced to Hawaii, but this is just a fraction of the more than 9,000 species found throughout the world. Members of the fern family vary from moss-like mini ferns to gigantic palm-like tree ferns more than 40 feet in height. There are many ferns that live attached to trunks and branches of trees such as the native bird nest fern, Asplenium nidus, and the Austral-Asian staghorn ferns, Platycerium species.
Most ferns prefer those shady, moist locations but some will take full sun, so there is a spot in your garden for at least one or two types.
A side benefit of ferns is that some are edible. Examples are the swamp fern and Warabi.
The swamp fern, Ceratopreris thalictroides, is found growing wild in moist areas and can be eaten raw or cooked. Our native tree fern, or hapu‘u, has an acrid substance so strong that the new leaf “fiddle” must be boiled outside for 30 to 45 minutes since they contain irritating fumes. After boiling, the outer skin is peeled off and the interior portions are soaked in fresh water.
The water is discarded and replaced with fresh water each day. This procedure takes three to four days. Then, they can be stored in the water and refrigerated for several months.
Fern shoots add an exotic touch to vegetable and pork dishes along with bamboo shoots.
Many edible ferns such as the Arythrium esculentum of Southeast Asia also are high in Vitamin A.
In the landscape, ferns give a lush rain forest effect. The most striking effect, by far, is created by the tree fern types. We take our native hapu‘u for granted, but in other parts of the world, different species are in great demand as landscaping plants.
In Hawaii, our native Cibotiums are being used in landscapes, but they are slow growing and are becoming scarce. The hapu‘u ii, or male fern, usually dies after transplanting. The so-called female fern can be transplanted before new leaves emerge in the spring, but often dies when planted out of its natural wet habitat.
To establish them, plant in a rich organic soil and keep them moist and shaded. Within a couple of weeks, they will begin developing large airy leaves and roots. A shady spot protected from wind is best. They should be watered on the trunk and at the base frequently.
Live stumps sometimes can be purchased locally. Do not remove ferns from the forests. It is illegal without permission. They are becoming rare in some areas because of cutting and removing.
This year’s extremely dry weather also is putting additional stress on hapu‘u. For example, the normally cool and wet cloud forests of Kaloko Mauka have received less than 2 inches of rain since the beginning of October.
Some other species of tree ferns are carried by a few local nurseries. These include types from Central America and the Caribbean, Southeast Asia and Australia.
Cyathea cooperi is not recommended as it naturalizes readily when conditions are ideal, but there are at least a dozen other species that do not naturalize easily. They are well adapted here and fairly fast growers. Under good conditions, they will produce fronds higher than your head in a year or so. With room, they will form a trunk to 10 feet or more. These species are more tolerant of sun and dry conditions than our native hapu‘u.
In cooler locations, the New Zealand tree ferns Dicksonia antarctica, D. squarrosa and Cyathea medullaris do very well. Here again, shade and moisture are the keys to success.
There are many other types of tree fern available including the Mexican Blechnum, which is a miniature type of about 3 feet. This is available at garden stores and some nurseries.
When planting ferns, be sure to enrich the planting sight by adding peat moss or rotted compost and some well-rotted manure to the existing soil. A good ratio is about 50 percent peat, 40 cinder and 10 percent well-rotted manure. New plants should be watered daily until they are established.
Ferns are sensitive to chemical fertilizers, so use them sparingly. It is better to use organics such as sewage sludges or rotted manures. Fertilize about once every two to three months for best growth. Avoid liquid insecticides and fungicides for they, too, will burn. Diluted wettable powders are safer. They are extremely susceptible to herbicides, so be careful.
This information is supplied by the University of Hawaii College of Tropical Agriculture and Human Resources. For further information about gardening and landscaping, contact one of our master gardeners at 322-4892 in Kona or 981-5199 in Hilo.
