Staghorn fern is a fascinating and unusual plant that grows wild in steamy tropical jungles, where it is found attached to the bark of large trees. Although staghorn ferns are resistant to most pests and diseases, problems can develop and they can be somewhat difficult to eradicate. The best way to keep a staghorn fern healthy is to replicate its natural growing conditions as closely as possible.
Stop watering the staghorn fern immediately if you notice black spots on the fronds, and move the plant to an area with good air circulation. This is a symptom of a fungus called Rhizoctonia, caused by too much moisture. The fungus can spread rapidly and can eventually kill the staghorn if it isn't stopped early.
Mount the staghorn fern where the temperatures is at least 65 degrees F. If the temperature falls below 55 degrees F, the fern's growth will be stunted.
Watch for pests such as brown and white scale, which look like a crust on the fronds, as well as mealybugs, which look like tiny pieces of cotton. An infestation can spread quickly and do serious damage--treat it with a non-oil based insecticide, following the instructions on the package. This product will be easier on the plant than an oil-based product.
Mist the fronds with a spray bottle if they're dusty. Never wipe the staghorn fern's fronds with a sponge or cloth, because this can remove the plant's protective fuzz and damage the plant.
Provide an appropriately sized, sturdy mounting surface for the staghorn fern. If it outgrows its mounting board, move it to a new one. It isn't necessary to remove the fern from its current board, just attach both plant and board to a larger, sturdier board.
Place the plant where it will receive bright but filtered light. Remember that, in nature, the staghorn fern receives dappled light filtered through branches and the forest canopy. Too little sun will encourage fungus, but too much direct sunlight will damage the plant.