tfeps - staghorn ferns

Once uncommon, staghorn ferns are now popular and widely available. They are ideally
suited to south Florida's growing conditions and will grow well in central and north Florida provided care is given to protect them from freezing temperatures.

Staghorn ferns are members of the Polypodiaceae plant family, and belong to the genus Platycerium. Eighteen species are presently recognized along with many varieties and
hybrids. Staghorns are tropical plants native to the Philippines, Southeast Asia, Indonesia, Australia, Madagascar, Africa and America. In their native habitat they thrive as epiphytes, generally found growing on tree trunks, branches, or rocks. Tropical rains provide moisture
and wash nutrients into the root area.

Staghorn ferns are valued for their highly variable and unusual growth habits. The plant
produces two distinctly different fronds (i.e., leaves), (a) basal and (b) foliar. Basal fronds,
often called “sterile fronds,'' are rounded thickened fronds which grow in overlapping
layers and clasp onto a growing surface. (Figure 1- below.) The upper parts of basal fronds
may be lobed or divided and stand erect. This upright form efficiently collects water, fallen leaves, and plant debris. These products eventually break down, releasing nutrients necessary
for growth. Foliar fronds, also called “fertile fronds,'' are either erect or pendant and may be divided into lobed or strap-shaped divisions. Foliar fronds produce brownish reproductive structures (called sporangia) on the underside of their fronds. (Figure 2 - below.) These
sporangia hold spores which, when germinated, form new plants. Both basal and foliar
fronds are covered to varying degrees, with small stellate (star-shaped) hairs giving them
a silvery cast. These hairs provide some protection from insect pests and conserve moisture.


Figure 1 -Sterile Fronds	Figure 2 - Underside showing sporangia

Varieties

For additional pictures of Staghorns visit http://www.rareferns.com/Platycerium.htm

Most species of staghorn ferns grow readily in Florida although much depends on the
familiarity of the grower with the specific needs of different species. Beginners are advised
to start with the “easy-to-grow'' species, which are readily available at local nurseries. As
you become accustomed to their culture and growth habits, you can start to acquire some
of the harder-to-grow and more expensive species. A partial list of species is provided below
with specific cultural information and notes on their ease or difficulty in growing.

Platycerium bifurcatum. The most common species in cultivation and also the easiest to grow. Produces large numbers of "pups," eventually forming a very large plant. Dark green color.
Hardy to temperatures of 25-30°F (1.1°C) for short periods. Many varieties are available. Native
to Australia and New Guinea.

P. veitchii. A common and easy-to-grow species with erect, silvery foliar fronds. Produces pups. Semi-hardy to temperatures of 25-30°F (1.1°C) and tolerant of light frost. A semi-desert species native to Australia that requires a lot of light.

P. alcicorne (P. vassei). Easy-to-grow species with upright fertile fronds, dark green. Basal
fronds turn brown naturally. Pups well. Semi-hardy to 40°F (4.4°C). Native to Madagascar
and East Africa.

P. hillii. Easy to grow with semi-erect dark green foliar fronds. Produces pups. Semi-hardy
to 40°F (4.4°C). Several varieties are available. Native to Australia and New Guinea.

P. stemaria. More difficult to grow, requiring temperatures of 80°F (26.6°C) and not below 50°F (10°C). Needs high humidity and frequent watering. Semi-erect, large foliar fronds with a
silvery case when young. Pups well. Large plant native to tropical Africa.

P. andinum. Moderately difficult. This dry forest species needs good ventilation, and drying between waterings. Fronds covered with dense silvery hairs. Pups well. Only Platycerium
native to South America, specifically in the mountains of Bolivia and Peru. Temperatures between 70-80°F (21.1-26.6°C), low of 60°F (15.5°C). Requires low light.

P. elephantotis (P. angolense). Moderately difficult. Thrives in warm temperatures of 80-90°F (26.6-32.2°C), low of 60°F (15.5°C). Produces large unbranched foliar fronds, dark green.
Basal fronds brown in the winter. Large fern. Native to dry forests of tropical Africa.

P. grande. Difficult to grow. Likes high humidity but is easily over-watered. Young plants
produce only basal fronds. Foliar fronds reclining, light green in color. Does not pup.
Tender below 60°F (15.5°C). A large fern, prized by collectors. Native to Philippines.

P. superbum. Difficult to grow. Very similar in appearance to P. grande when young. Easily over-watered. Large reclining foliar fronds light green in color. Does not pup. Hardy to
30°F (1.1°C) for short periods, although prolonged cold temperatures not tolerated. Prized
by collectors. Native to Australia.

P. wandae. Difficult to grow species. High humidity, easily over-watered. Temperatures
between 80-90°F (26.6-32.2°C), lows of 60°F (15.5°C). Possibly largest Platycerium. Native
to New Guinea.

Care and Culture

Mounting

Because of their relatively large size, staghorn ferns are rarely grown in pots except when produced as small specimens for sale at nurseries. Their natural, epiphytic growth habit makes them well suited for mounting on slabs of wood, tree fern fiber or wire baskets. To mount a
fern on a piece of wood or tree fern fiber, place a few handfuls of organic growing medium
such as peat, compost or rich potting soil on the wood slightly below center. Shape it in a
circular mound and place the fern on it so that the basal fronds are in contact with the
mounting material. Use wire (not copper), plastic strips or nylon hose to secure the fern
tightly to its mount. When a wire basket is used, pack it with an organic medium and mount
and secure the fern “face-up” on the medium. Hang the basket sideways. Pups (small plants)
will eventually emerge from the back and sides of the basket and completely cover it.

Watering

In general, allow the medium to dry completely between watering. This may be difficult to
judge since the outer medium may appear dry, but the inner layers and the basal fronds will
be saturated. It may be best to wait until the fern slightly wilts before watering. Once watered,
it will quickly recover, whereas an over-watered fern will rot and die. Generally, water once a week during dry, hot times of the year, and less during winter and rainy seasons. Older plants, those with spongy layers of old shield fronds, tolerate drought better than less mature plants.

Fertilization

A water-soluble fertilizer with a 1:1:1 ratio (i.e., 10-10-10, 20-20-20) is recommended. Staghorn ferns can be fertilized monthly during the warm, growing months of the year and every other month when growth slows down. Frequent fertilization is only necessary when you want
vigorous growth. Large or mature staghorns will survive and thrive with one or two applications
a year of controlled-release fertilizer.

Light

Most staghorn ferns thrive best under partially shaded conditions. The dappled light of a shade tree or indirect light on an outdoor porch is ideal. This is the equivalent of 600-2000 foot candles. Very low light conditions produce slow growing ferns that are likely to develop disease and
insect problems.

Temperature

Most staghorn ferns are considered tender or semi-tender to cold and will not tolerate cold temperatures. There are exceptions, such as P. bifurcatum and P. veitchii, which can withstand temperatures as low as 25°F (1.1°C). South Florida growers will have relatively few occasions when cold protection is needed. Most staghorns grown outdoors are usually in protected, naturally warmer microclimates such as under tree canopy. However, central and north Florida growers should be prepared to bring ferns into a heated garage, greenhouse or home when extremely cold temperatures are predicted.

Propagation

Propagating staghorn ferns from spores is slow and difficult and is not practical for most gardeners. Pups (with their root systems) can be carefully removed from large ferns and re-established. Wrap the roots in damp sphagnum and then tie the root ball to a mount. Eventually the sterile frond will expand and grip the mount.

Problems

Staghorn ferns are fairly pest free. When kept too wet, they are susceptible to a disease
called Rhizoctonia sp. This fungus produces black spots on the basal fronds which can
spread rapidly, invade the growing point, and kill the plant. If symptoms appear, withhold
water and reduce the humidity to slow the spread. Chemical controls are available and
generally effective when used as directed.

The insect pests to watch for are mealy bugs and scales. Insecticides are effective against
these pests but may burn or deform the foliage. Generally non-oil-based insecticides are safer
on staghorn ferns than oil-based compounds. Other pests such as snails or slugs can be a
problem but are easily controlled. Contact your county Extension office for specific recommendations for disease and insect management: http://solutionsforyourlife.ufl.edu/map/

Staghorn Ferns at a Glance by Sydney Park Brown