Hawaiian Tree Fern Culture

Culture

• Hawaiian tree ferns are most frequently found as undergrowth in moist to wet forests at elevations between 1,500 to 5,000 feet. As plants native to tropical areas, Hawaiian tree ferns grow best in moist, well-draining, slightly acidic soils, high in organic matter. They prefer partial shade, but, according to the University of Hawai‘i at Manoa College Cooperative Extension Service, they tolerate full sun in cool, wet areas or filtered shade in warm, dry, areas, if watered frequently. Tree ferns are sensitive to high-soluble salts, so the cooperative extension service suggests using organic fertilizers such as fish emulsion and well-rotted manures; low rates of inorganic fertilizers with a 1:1:1 ratio of nitrogen, phosphorus and potassium; or a time-released fertilizer.

Destruction

• Like other tree ferns, Cibotium glaucum has been over-harvested for orchid growing media, landscape uses or removed for development. Although international laws regulate the shipment of plants from one country to another, it, like other tree ferns, is threatened in its native areas due to activities such as land clearing and farming. The University of Hawai‘i at Manoa College Extension Service recommends planting the Hawaiian tree fern where conditions are ideal for its establishment and to use only plants from nurseries, if possible. Otherwise, propagate Hawaiian tree ferns from side shoots at the plant's base or from spores, although the latter method is more challenging.

Propagation by Cuttings

• Cibotium glaucum is often propagated from side shoots growing from main trunks, although plants propagated from this method grow more slowly than plants grown from spores. Remove cuttings of any sized shoots with a sharp, clean knife, in early spring, before new growth of fronds begins. Cut off a shoot at the point where it connects to the main trunk. Remove the leaves and place the cutting in moist and cool conditions -- for example, by misting and placing it in a garage or basement -- and allowing the pithy base to partially dry. For the best chances of establishment, plant tree ferns in wet, cool areas, but with well-draining soil. During establishment, keep the trunk moist and protected from drying winds, such as by using a wind shield, which can be purchased at garden centers.

Propagation by Spores

• To propagate Cibotium glaucum from spores, remove mature, healthy frond branches from the main frond stem when the spore cases -- or spori -- are plump, and dry each frond in separate paper bags or folded newspapers. To prevent moldy spores, dry off fronds by placing the bags in a single layer in a warm, dry location for two or three days. The ripe spores -- which resemble dust -- will fall off from the fronds, though more slowly when the weather is cold or very humid. Separate spores from debris with a fine screen, then sanitize the growing medium to prevent fungal infections. The University of Hawai‘i recommends using a commercial mix containing sphagnum peat, vermiculite and perlite, moistening it with distilled water then microwaving it in a lidded container on high for 10 minutes. Spread the medium in a sterile plastic tray with a clear, plastic lid, and cool. Add spores to the medium surface, mist with distilled water, cover and keep it free from contamination. Spores germinate in warm, lighted environments; avoid full sunlight. Sporelings develop after several weeks.