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At Home with Ferns
by Mobee Weinstein
If you find yourself fascinated with ferns, congratulate yourself. You are among a select group of people described as follows by Herbert Stansfield in the mid 1800s: "The bright colors in flowers are admired by the least intellectual, but the beauty of form and textures requires a higher degree of mental perception and more intellect for its proper appreciation."
Growing ferns indoors first became popular in England in the 1800s, and reached its peak in the 1850s, during the so-called Victorian Fern Craze. Fern cultivation was a highly fashionable fad, which arose purely for aesthetic reasons. Fortunately, technological developments in heating and the manufacture of glass coincided, allowing people to pursue their new passion. The intense preoccupation with ferns further stimulated academic studies, and scientific interest was also fostered by improvements in microscopes and their greater availability. As in other sciences, in fashion, music, dance, and the other arts, horticultural trends cycle around, coming in and going out of style. Presently these "semi-antique" plants are enjoying a revival, much like heirloom vegetable and flower varieties.
Nephrolepis exaltata, Boston fern.
To most people, the word "fern" conjures up certain images—delicate, lacy, airy greenery luxuriating in a shady little spot. While this may be true for some ferns, these plants are more diverse than most people think. Ferns originated about 300 million years ago, and there are about 12,000 species of ferns and fern allies growing on the earth today. Their leaves vary in size from 1/8 inch to 60 feet, and their colors range through the full spectrum of green and also white, silver, golden yellow, red, pink, copper, and burgundy, even blue. Fern fronds come in different textures and can be thick and leathery, somewhat succulent, hairy, waxy, or super thin—only a single cell layer thick! The majority of ferns make their homes in moist tropical forests, but they also venture into cold temperate zones, bodies of water, and even the desert. These somewhat primitive plants do not flower or set seed, but rather reproduce by spores. However, they do have a vascular system, a relatively advanced feature, which is basically a network of veins for the transport of water, nutrients, and food. Their stems are often modified into "rhizomes"; at times these are very obvious and showy, and at other times they're hidden in the soil.
From a design perspective, ferns are very versatile. Their quiet, graceful beauty lends itself equally well to classical, formal styles and rustic, informal settings. A perfect example is the Boston fern, the most common fern grown in America today.
Growing Ferns
Most people shy away from growing ferns, thinking that they are all too difficult. However, with proper selection and care, they are very gratifying plants.
Humidity
With many ferns, humidity is the key to success. Most require at least 35 percent; 40 to 50 percent is even better. The typical home has 10 to 25 percent, especially in winter, and in summer as well if an air conditioning system is being used.
Humidity is a relative factor, hence the term "relative humidity" (RH). Cooler air has less of a capacity for holding moisture than warmer air. With the same amount of actual moisture in the air, 55° F. will have a higher relative humidity reading than 65° F. So you begin to see why keeping plants cooler, especially in winter, is beneficial. There are several things you can do to increase the humidity around your plants. Running a humidifier will produce the best results, and it's also good for you, your wood furniture, books, paintings, and so on. Mass or group your plants together, and/or set them on trays of gravel filled with water, but be certain to raise the bottom of your containers above the water level. Add a few pieces of charcoal to the tray, and clean it thoroughly with a 10-percent bleach solution or scalding water every two months or so.
Victorian growth chambers were needed to provide humidity, but also to maintain warmth and protect plants from the noxious fumes of coal heating.
You can also mist ferns with larger leaves, but bear in mind that one little spritzing a day won't increase humidity for very long—when the droplets have dried up, the humidity is basically gone! An alternative is to enclose your plants in a terrarium of some kind. Fancy growth chambers date back to Victorian England. At the time they were needed not only to provide humidity, but also to maintain warmth and protect plants from the fumes of the burning coal that was used as a heating fuel. Now such growth chambers are sometimes used to provide additional warmth, but mainly to maintain humidity.
Temperature
The majority of ferns that are available to us as houseplants originate in the tropics and prefer a daytime temperature ranging from 65 to 75° F.; the nighttime temperature should be 10 degrees cooler, ranging from 55 to 65° F.
Light
Contrary to what many people think, ferns do not grow in the dark! They are photosynthetic creatures just like other plants. Ideally, ferns prefer bright, indirect light for best growth, and many will benefit from a little sun in winter. Many will tolerate lower light, but under these conditions, they merely survive and won't grow very much.
Soil mixes
When it comes to potting and soil mixes, it is useful to divide ferns into two categories: terrestrial and epiphytic. Terrestrial ferns grow naturally in the ground and make good potted plants. For these ferns, use a soft, organic soil mix such as: 2 parts loam, 2 parts organic matter (leaf mold, compost, or peat moss), 1 part perlite, 1 part vermiculite, 1 part charcoal, and 1 part very fine grade orchid bark. Ferns tend to have small, delicate root systems, so when potting, don't disturb the root ball too much and firm the soil in place, but don't "pack" it in.
Epiphytes naturally grow up in trees, or on rocks, etc., not in the earth. Most epiphytic ferns have an extensive rhizome system that grows around their "support structure." The rhizomes will grow all around your basket or pot, so they should be "planted" on the surface and then allowed to grow "outside" the container. Epiphytes require a different mix: 1 part of the terrestrial mix above combined with ½ part of very fine grade orchid bark and ½ part tree fern fiber.
Pests
The most common pests on ferns are scale and mealybug. Picking mealybug off by hand or with a Q-tip dipped in alcohol or soapy water is very effective, although tedious. Scale is even more difficult to remove manually. Another non-chemical control is to release some beneficial, predatory insects..
Propagation
Propagating many ferns is easy. Those that grow in a clump can be divided using typical methods. Many epiphytes can be propagated from rhizome (stem) cuttings. These take best if the pieces have at least one leaf and preferably roots. Some ferns, commonly called "mother ferns," make baby plantlets along their leaves, and these can easily be separated and grown in a separate pot. Most ferns can also be grown from spores, which is not as difficult as it may sound, but takes much longer.
Mobee Weinstein is assistant foreman of gardeners at the New York Botanical Garden, where she has worked for the past 20 years. She is a graduate of the NYBG School of Horticulture and received a Bachelor's Degree in Plant Studies. Her primary work is with ferns, tropical, and aquatic plants and she is a past president of the New York Chapter of the American Fern Society. She is an instructor for the NYBG School of Professional Horticulture and Continuing Education Department, is an Adjunct Professor for SUNY at Farmingdale and lectures frequently.
Top photo: Alan and Linda Detrick; bottom photo: Mobee Weinstein