INDOOR FERNS

by Joelle Steele

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Ferns, botanically known as Filices, are native to all parts of the world, but are most often found in the tropics and subtropical areas. Some are epiphytic in nature while others make their homes on the shaded floors of tropical wood forests.

Many interiorscapers dismiss ferns as being too messy and therefore too hard to maintain. But, while some of the messiness seems characteristic of certain species, it can be reduced by proper care, and, there are alternative species which are more exotic and less problematic.

COMMON INDOOR FERNS

Here are some common indoor ferns: Acrostichum aureum ("Leather fern"); Asplenium ("Birdsnest ferns and Mother ferns"); Cyrtomium falcatum ("Holly and Fishtail ferns"); Nephrolepis exaltata ("Bostons, Lace, Feather, and Sword ferns"); Pellaea rotundifolia ("Button fern"); Platycerium ("Staghorn and Elkhorn ferns"); Polypodium aureum ("Hare's foot and Crisped blue ferns"); and Stenochlaena ("Liane fern").

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HUMIDITY

The biggest problem with ferns is the lack of humidity occurring in the dry air of highrise office buildings. If you install ferns in these difficult environments you will surely experience the light browning and abscission of foliage characteristic of low humidity. Light, regular misting is essential wherever these plants are installed, but it's best to save ferns for residential clients or for offices located in older buildings with windows that open.

WATERING

In trying to combat the low humidity symptoms, it is not unusual to overwater. With some species, such as nephrolepis which is usually very rootbound, this is not usually a serious problem. But, with asplenium nidus and polypodiums, overwatering can spell death. Ferns like to be moist but they don't like to get their feet too wet — that goes for their rhizome "feet" too. While underwatering may cause leaf loss, that is only a temporary condition. Overwatering can be a death sentence with ferns.

FERTILIZATION

Ferns require little fertilizer. They obtain most of their nutrients from the air and unless they are sitting in more soil than roots, they should be fertilized only very lightly and only when the soil is moist. Overfertilization results in burning and tipping. Light feeding twice a year in the growing season is sufficient.

LIGHT AND TEMPERATURE

Ferns do well in warm or temperate conditions but may suffer cold damage if temperature drop below about 50 degrees F. They can tolerate light levels ranging from about 100 to 1000fc but will really thrive up to 3000fc. Anything over that is likely to be damaging.

PESTS AND DISEASES

Ferns suffer few diseases, but, like most plants, they have their share of pests. The most common problems are brown scale and mealy bug. These problems are particularly common to the smaller leafed species, such as nephrolepis, but are also found on pellaea and stenochlaena. With nephrolepis, both can infect the root system very quickly and be extremely difficult to control. As usual, careful plant selection is of the utmost importance in preventing infestations before they begin, and close inspection during maintenance will alert you to a problem before it becomes a catastrophe.

This article last updated: 04/11/2000.