There are many positive things that can be said about houseplants. Research has shown that including plants in the home can reduce stress and elevate one's mood. Houseplants also help to purify the air and add humidity to the interior setting, which is good for one's health. Additionally, caring for them tends to promote a sense of accomplishment, thus imparting a feeling of self-worth. Couple these benefits with the fact that houseplants are attractive and it is no wonder that, to many people, a home is not complete without attractive potted plants.
It is important to remember that there are no houseplants in nature. Instead, horticulturists have identified certain species that seem to be able to tolerate interior conditions better than most and labeled them as houseplants. Ferns are examples of plants that tend to put up with the environmental shortcomings of an interior setting, making them, for the most part, durable houseplants.
Fern is somewhat of a generic name applied to species of the plant families Woodsiaceae (terrestrial ferns) and Aspleniaceae (epiphytic ferns). Ferns are primitive, non-flowering plants that reproduce by forming spores instead of seeds. Most ferns grow from underground stems known as rhizomes; their emerging leaves are called fronds. There are nearly 12,000 species of ferns, but only a relatively few of these make good houseplants.
One of the most popular and suitable of all ferns for indoor use is the Boston, or sword, fern (Nephrolepis exaltata 'Bostoniensis'). It produces long, graceful fronds that cascade over the containers in which it is planted. The fronds of the Boston fern are fairly long, each one reaching up to three feet in length. This fern was first found as a chance mutation by a florist near Boston, MA in 1894. It soon became the most popular fern of the Victorian period and has received several awards, including the British Royal Horticulture Society's 'Award of Merit'.
Many variations and selections of sword fern have appeared over the years. For example, Nephrolepis exaltata 'Whitmanii' is more compact with fronds no more than 18 inches in length. 'Fluffy Ruffles' bears dense, bipinnate fronds only 12 inches long. 'Dallas' fern (originally plant patented) also has fairly dense growth and is more tolerant of lower humidity than most other varieties of this species. 'Rita's Gold'™ has compact, golden-yellow fronds that tend to brighten any interior setting. Finally, 'Rooseveltii' is a variety of sword fern that produces exceptionally long, graceful fronds to a length of four feet.
Another interesting fern for the home is the bird's next fern (Asplenium nidus). An epiphytic fern in nature, its fronds are not divided into small segments as is the case of the Boston fern and its related varieties. The leaves of bird's nest fern are large, long and narrow. They emanate from a rosette center which forms a symmetrical "nest," or bowl-shaped plant. Its leaves are somewhat leathery in appearance and feel, and are fairly tolerant of low humidity. Bird's nest fern grows best with a bit brighter light than the Boston fern. It should have a fairly constant supply of moisture at its roots, but can endure drier conditions than most other ferns.
Another epiphytic fern with an interesting name is staghorn fern (Platycerium bifurcatum). This fern produces to types of fronds: sterile (non-reproductive) and fertile (reproductive). Sterile fronds are rounded to heart-shaped, overlapping, shield-like structures at the base of the fern. The forked fertile fronds emanate from the overlapping sterile fronds and grow to a length of about 18 inches. Although bright green, they resemble the antlers deer or elk in overall shape; hence, the plant's unusual common name. It grows best in a warm, humid environment in bright, indirect light. As an epiphyte, staghorn fern is often grown mounted on a board with sheet moss covering the plant's root system. Watering is accomplished by immersing both fern and mounting board in a large, water-filled container for several minutes and then allowing it to drip dry. Given a suitable location can be found, staghorn fern does quite well outdoors during summer months.
The holly fern (Cyrtomium falcatum) has dark, glossy green leaves. Native to Asia, it sometimes goes by the common name of Japanese holly fern. The individual leaflets of the fronds of holly fern are fairly coarse, but each one has a crinkled margin, making it similar in appearance to the leaves of English holly. Like most ferns, it needs fairly cool house temperature at night of about 55 to 65° F. It is not as tolerant of drying as is the bird's next fern.
There are many varieties of maidenhair fern (Adiantum spp.) that make attractive houseplants. They are tolerant of low light, but not of drying. If a maidenhair fern becomes too dry, the top will quickly die off. At that point, it will need to be cut off. If the roots were not too badly damaged by the drying, new growth again will develop from the base of the plant. The maidenhair ferns used indoors are of tropical origin and not the same maidenhair fern that can be planted outdoors in shady woodland settings.
Table ferns (Pteris spp.) are relatively small plants suitable for small pots, or for use in combination planters or terrariums. There are many varieties, but those with silvery venation (e.g., Cretan brake fern) are the most popular. These ferns tend to spread through the pot and will need occasional division and repotting to keep them growing vigorously.
The tree ferns are the ultimate interior plants for fern lovers. However, they are not easy to grow. Majestic plants, tree ferns can achieve heights of over 35 feet in nature. The Hawaiian tree fern (Cibotium menziesii) is one of most easily found in commerce. However, because of their size, tree ferns are not as easily grown as the smaller ferns. The size of most would dictate the need for an atrium or hobby greenhouse. They must be kept wet at all times because even a single drying can cause substantial damage. Therefore, it is best to keep a small amount of water in a saucer beneath their pot. Tree ferns, particularly the Australian tree fern (Sphaeropteris cooperi), is one of the few ferns that tolerates very wet conditions. Do not allow other potted ferns to sit in water for any length of time.
Ferns should be grown in a potting mix that provides good drainage and is high in organic matter. Fertilize only when ferns are actively growing in the spring through early fall months. Most ferns need bright, indirect light of at least 500 f.c. for about 14 hours or more each day. In nature, the majority of ferns are understory plants. Therefore, never place them in direct sun locations in the home. Where sufficient natural light is not available, artificial lights will help plant growth.
Cool night temperatures (55 to 65° F.) are the key to maintaining ferns in good condition indoors. High night temperatures increases water absorption, lowers humidity and often causes leaf yellowing and drop. While the ferns that have been mentioned here are the best types for indoor use, they still benefit from high humidity. Placing their pots on pebbles in water-filled trays for evaporation can help raise the humidity in the microclimate surrounding the fern. This step is particularly important if the cool temperature conditions mentioned previously are not possible.