Most city dwellers have fond recollections and enduring impressions of woodland glades and mountain ravines where the green coolness was enhanced by ferns. The ferns flourished in soft spongy soil, rich and fibrous through its annual renewal with falling leaves and twigs.
Not all ferns grow in cool, dark shade. Many are found on hillsides, in swamps and meadows; some live on the branches of jungle trees. Their degree of hardiness differs widely. Under cultivation the hardy ones are often grown in the garden. The tender ones are good housplants.
Ferns are among the oldest known plants. Though their stucture and method of reproduction may seem complex, they are considered a primitive form of plant life. They have no flowers, hence set no seed. They are propagated by division, by runners, and also by spores, distinctive reproductive cells borne on the leaves.
The indoor gardener interested in growing ferns should visit a well-stocked florist shop or greenhouse specializing in ferns to learn something of the wide assortment of species and their cultural requirements.
One of the first things to be learned is whether the chosen fern is terrestrial or epiphytic because there is a difference in the way the two types are handled. A terrestrial fern grows on the earth - in woods, fields, swamsp, cliffs, mountains or lowlands. Boston fern and brake or table fern are examples. An epiphytic ferns grow son tree branches, but it is not a parasite; its roots are adpated to grasping support and absorbing moisture from the air and sustenance from fallen leaves and bird droppings that accumulate around the plant. Examples are Staghorn fern and Rabbit's Foot (Davallia). A third type is aquatic; it lives in water and is not adaptable to cultivation.
Management of light, soil and moisture is the key to growing ferns in the house. Their preference for moderate temperature and shaded sunlight makes them ideal houseplants and good in terrariums. The tender ferns grown indoors grow best in natural light from north windows. Second best is an east window.
In other locations, curtained shading from direct sunlight is need. Winter sun, which is of shorter duration and less intensity than summer sun, is not too bright for most ferns. They can be grown also under fluorescent light - 14 hours of light per day. Finally, the amount of light needed depends on the type of fern, and it definitely influences the rate of growth.
Knowing whether your fern is terrestrial or epiphytic is important in order to select a suitable growing medium. Basically, a loose mixture, rich in humus and fibrous material and well-drained is recommended.
For terrestrial ferns, use a mix of peatmoss and perlite or sand; grow epiphytes in osmunda fiber or fir bark. Packaged mixes, such as Rediearth, Pro-Mix or Jiffy Mix, may be used; just be sure that it is a type that is loose, well aerated and well drained.
Whichever mix you use, dampen it with warm water before you plant the fern to make it easier to mix and pot and safer for the fern.
Start small ferns in small pots and shift to larger pots as the plants grow and crowd the pot. Most ferns like to be potbound. Ferns have shallow roots, so a shallow pot is preferred. Either plastic or clay pots may be used; remember the difference in watering - the day pot dries out faster. Some epiphytes, such as the popular Staghorn, are grown on wooden or cork slabs, or in wire baskets or "log-cabin" boxes, rather than in pots.
Learning to water ferns is critical. Growers acknowledge that watering is a difficult technique to master. Always use tepid water. Some ferns require more water than others, no formula can be given because there are so many variables in type or sixe of fern, type of container and environment in which it is grown.
Most ferns should be kept moist but none should be allowed to stand in water or to endure soggy soil. Supply enough water to thorougly penetrate the soil and allow the excess to drain away. Just as with other plants, over-watering will kill.
Large Boston ferns can best be watered by immersing the pot in a pail of water for an hour twice a week - depending upon the dryness of the house. They can be set outdoors in a gentle rain for a cleansing refreshing bath when the temperature is above 50 degrees.
Staghorns mounted on a plaque or in a basket should be immersed in water every five to seven days until bubbles no longer rise in the water. This assures thorough soaking of the fiber in which they grow; once it dries out it is difficult to get the fiber moist again. Staghorns growing in pots frequently suffer from overwatering.
Moisture in the air is as important as moisture in the soil. Relative humidity of 50 per cent or higher is recommended. Dryness of the air is especially injurious to soft-leaved types, such as Maidenhair. Using a mist spray three or four times a day will help to maintain luxuriant growth. Misting is good for broad-leaf ferns and those of simple-leaf forms. Use less spray on crinkled varieties, which tend to collect moisture and hold it, contributing to development of fungus.
Humidity can be increased in the vicinity of the plants when pots are set on trays of moist pebbles or on damp sand. Installing a humidifier is a means of increasing humidity, which is good for other plants and for the human occupants of the house as well as for the ferns.
Fertilize monthly with a water soluble house-plant food. Use 20-20-20 or 20-10-10 diluted to half the strength recommended by the manufacturer. Fish emulsion is also a good fertilizer for ferns. Do not feed from mid-October to the end of January, when the plants are not in active growth.
Be cautious about introducing new plants to your collection; quarantine new plants until you are sure than no pests have come with them.
Try to keep ferns pest-free by other means than chemical sprays. If a plant is heavily infested with scale or mealy bug, it is best to destroy the plant. Insecticides containing petroleum derivatives destroy fern foliage and roots and many harsh commercial spray compounds are harmful to ferns. Read the label - it is required to list plants on which the product can be safety used.
Common pests of ferns are scale and mealy bug, and fungus may become a problem.
Soft brown scale, appearing as small round dots on the back of the leaves, can cause serious damage. If there are only a few scales present, pick them off. A soft toothbrush gently applied is also effective. Scales appear haphazardly on the back of fronds; sometimes they can be seen to move.
The small brown or black dots (sori) in which fern spores are produced are arranged in characteristic geometric patterns on the frond. If you remember this distinction it will save you needless worry and also perhaps prevent your defacing the fronds by unnecessary treatment.
Mealy bugs can be removed with an artist's paint brush dipped in nicotine sulfate solution.
A fungus attack causes fronds to break and fall over. It is usually the result of over-watering. Treat it by application of benomyl to the base of the plant.
The beauty of ferns is in the variety of leaf patterns and types of growth. Allow space around them for beauty and health. Crowded and brittle fronds become entangled and break. Ferns are easily damaged by people brushing against the tips of fronds. Damaged fronds should be removed.
Cleanliness and constant grooming are necessary to attractive and healthy plants. Sometimes emphasis placed on growing plants that produce "constant" bloom obscures the pleasure of growing plants for their foliage alone which is the fern grower's reward.