Temperature

Room temperatures which are comfortable for people are usually too warm for ferns. Daytime temperatures for successful fern growth should not exceed 72°F. Night-time temperatures should be on the cool side, below 60°F.

Humidity

Low humidity around the home, usually averaging 10 to 15 percent, can be a problem for many tropical indoor plants. Thirty percent humidity is about as low a level as a fern can tolerate. Forty to 50 percent humidity is a more desirable range.

Symptoms of plant damage caused by low humidity include browning and drying of the tips of the leaves or fronds. Also, yellowing and dropping of interior leaves can mean that the atmosphere is too dry.

There are several methods for overcoming the low humidity problem. One way is to add humidifiers to your home heating system or to buy a self-contained electric humidifier. Another way to raise humidity around your plants is to place potted plants in saucers or trays filled with gravel. Then add water to the trays or saucers, maintaining at least 1/4 inch of water at ail times. The water that evaporates from the gravel surface will increase the humidity around your fern. Double-potting your fern is another method of raising humidity. Place the potted fern inside another container—perhaps a decorative pot—and fill the area between the pot and the container with pea gravel or spaghnum moss. Now, keep the moss or gravel moist to humidify the plant. Many people suggest that misting on a daily basis helps to raise humidity. Actually, misting only helps remove dust from the plant leaves. The previously mentioned methods are more effective and less time consuming than misting.

Light

Because ferns grow in a wide range of native habitats, there is a fern suited to most light conditions found in the average home. For example, a north or east window usually provides good light conditions for ferns, while south, east, and west windows will probably need a reduction of light. A sheer curtain will help reduce light penetration. Or simply position the fern far enough from the window to avoid direct sunlight.

Remember, asparagus ferns are not ferns at all, but members of the lily family. Therefore they require bright, direct light all year around. Refer to Table 1 for light requirements and other needs of specific ferns.

Potting

Choose a clean clay pot, plastic pot, or decorative container for your fern. Anything can be used if it has a drainage hole at the base of the container to remove excess water. Gauge the selection of your container to the size of your plant. Small plants should be in small pots, and larger plants should be in large pots. It is a common misconception that a small plant in a large pot will have “room to grow.” It is more likely that it will drown in the excess water which is being held in the soil.

The soil mix is an essential part of successful fern culture. A typical mix contains equal parts of peatmoss, sand, and garden soil. Pasteurize this mix by baking it in a closed container (such as a roasting pan) at 200°F for 20-25 minutes. This baking destroys disease-causing organisms.

Water

There are no hard and fast rules about watering ferns. The best way to determine when to water is to know your plant requirements and to use the “dirty finger method” for checking soil moisture. Feel the soil to determine its moisture level. Some ferns, such as the Boston Ferns, should be watered when the soil becomes slightly dry on the surface; others, like the Maidenhair and the Button Fern, need to be continually moist. When you water, use room temperature water and thoroughly soak the soil until water drains from the bottom of the pot. Plants should not be allowed to sit in the drained, excess water.

Your watering practices help determine your success with ferns. If plants are over- or underwatered, shedding of leaflets will occur.

Of course, no one factor will determine successful indoor growth for ferns or any other plant. But the factors discussed in this publication are the basics for successful fern growth, and all elements must be given attention to adapt tropical ferns to indoor conditions.

Organizations

The following organizations are additional sources of information about fern culture.

• The American Fern Society
• Los Angeles International Fern Society

Related Publications

Contact your county Extension office to receive copies of the following publications.

• HO-1 New Plants from Layering
• HO-39 Indoor Plant Care

The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by the Indiana Cooperative Extension Service is implied.