by Joelle Steele

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The histories of the interior landscape and floral industries go back to the dawn of time. People have been using plants and flowers to decorate their homes — and even their bodies — since prehistoric times.


Long before dinosaurs arrived on earth there were cycads, plants most closely related to today's conifers. In fact, there were so many huge forests of giant cycadean plants covering the earth during the Mesozoic era that it is often called the Age of Cycads, and our present coal resources consist, in large part, of the remains of those ancient plants which died over 200 million years ago. Today less than a dozen cycad genera still exist, one of which, the popular "sago palm" (Cycas revoluta), makes an excellent houseplant due to its relatively compact size. Despite its common name, the cycad is not a palm or a fern, but a type of tree called a gymnosperm, an evergreen which bears cones when it reaches maturity.


Plants were first used for purely practical purposes, for their nutritional and medicinal qualities. But by ancient times — more than 3,000 years ago — they were also being used decoratively. Images of potted plants are found on walls of tombs and ruins in Egypt, Greece, Italy, China, India, Iraq, and other sites of ancient civilizations. In the ruins of Pompeii there is evidence that plants were grown indoors in terra cotta pots. We don't know what they grew in those pots two-thousand years ago, but we can speculate that they probably contained laurels, myrtles, evergreen shrubs, dwarf citrus, and possibly even some imported tropical specimens. But Pompeii is not necessarily the oldest example of indoor gardening.

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The Egyptians began growing plants in their sparsely furnished homes during the third century BC when they, like the residents of Pompeii, began adorning their inner courtyards with plants in terra cotta pots. Around that same time, container gardening was a common practice in Greece and Rome where plants adorned inner courtyards and rooftop gardens. By the first century AD, the Romans were building hothouses and conservatories using talc and mica for windows. These ancient greenhouses were heated in order to grow roses, grapes, lilies, and other exotic plants which required a hot, humid environment.


After the fall of the Roman empire, ornamental gardening became a thing of the past. Medieval gardens were primarily grown and tended by the Christian and Islamic religious orders and were purely functional. They grew mostly fruits and vegetables as well as herbs which were widely used for medicinal and culinary purposes. It was not until the advent of the Renaissance that the art of ornamental container gardening was revived. During the time of Columbus, the widespread exploration of distant lands was contributing to a wealth of exotic plants being grown purely for their decorative purposes, and many of those plants were the precursors of our modern-day indoor ferns, ivies, and succulents.

The art of growing house plants did not receive much comment until the 1600s when glasshouses (now called greenhouses) and conservatories were first built to accommodate exotic plants. Orangeries and greenhouses became common features of the homes of the wealthy and landed gentry. The Palace of Versailles had an orangery that could hold 1,200 citrus and 300 other delicate plants. In England, monarchs William and Mary collected exotic plants and maintained them in three hothouses where they were grown in lead or stone containers.


The style of indoor gardening which we would be more likely to recognize today, and which was the forerunner of indoor gardening in the Victorian age, had its start during the 1700s, at which time more than 5,000 exotic plant species had been introduced to the people of England, who housed these temperamental beauties in temperature-controlled greenhouses. At that time, the Americans were not terribly interested in exotics and it was not until the late 1700s that the first hothouse for tropical plants was built in the United States.

Gardening in general was in its hey-day at this time. It was big business and it was a big hobby. New varieties of plants were being cultivated by master gardeners, and gardening itself was considered a worthy and respectable pursuit of the aristocrats of the time.

It was during this era that the classification of plants began. It started with a man named Carl von Linné or Carolus Linnaeus (his ennobled name). Linnaeus was a Swedish botanist, zoologist, and physician. He was a university professor and department chair, and he was one of the most acclaimed scientists of his time. In fact, he is known for the design of our modern-day thermometers in which water boils at 100 degrees and freezes at 0 degrees. It used to be the other way around!

Linnaeus collected and classified plants and other living things. The saying goes, "God created, Linnaeus organized." And organize he did. He developed the basis for our current scientific classification system known as "Linnaean taxonomy," in which Latin names are used to describe and classify living things. This naming process is called "binomial nomenclature," or "two-name naming." Today, we rely heavily on binomial nomenclature in all the sciences, including horticulture and medicine.


By the mid-1800s, books on indoor house plant care began to appear and terrariums became a popular home decoration. Paintings and photographs from the Victorian age show foliage plants being used indoors. Private greenhouses and public conservatories of the time were positively overflowing with rare and unusual plants that were extremely popular with the wealthy and the middle class. Even the lowliest parlor had at least one big splashy potted palm or Boston fern. In England, where indoor gardening first became popular, almost everyone had a window garden, and most people of average intelligence knew something of the care and maintenance of indoor plants.

Indoor gardening was a pastime that was considered to be morally stimulating. It was accepted as a respectable hobby, and gardeners of any kind were revered as true craftspeople. Popular Victorian houseplants included azaleas, begonias, camellias, grape ivy, dracaenas ("corn plants"), ficus trees ("fig trees"), geraniums, pothos, palms, philodendrons, and wandering jews. In private homes, these plants were usually set in hanging baskets or placed in groups on tiered wrought-iron stands. In public places, such as hotels and theaters, huge tropical plants were displayed in lobbies and sitting areas, much as they are today.

Despite the enormous demand for indoor plants, the Victorian indoor environment could hardly be considered an ideal place to grow plants. The rooms of most houses and buildings were dusty with common house dust at a time when there were no vacuum cleaners. Rooms were also filled with the dark and deadly pollutants that came from the use of coal heat. Buildings were rarely insulated, and rooms were either cool and drafty, or overly warm. Ventilation was inadequate, but the heating stoves did provide some measure of humidity suitable for tropical plants. Lighting was also at a premium. Gas lamps provided only dim light, and heavy drapes covered windows to keep drafts from blowing through the less-than-airtight windows and to prevent the sun from fading the fragile dyes used in carpets, upholstery, and wall coverings.

But flowers from the garden could be easily cut and placed in elaborate arrangements in these indoor environments, and so the floral industry was really off to a roaring start before the interior landscape industry caught on.


One of the earliest pioneers in the floral industry was a man named Julius Roehrs. In 1864, he came from Germany to the United States and settled in New Jersey, which was then the growing capital of the country, leading to its nickname, the "Garden State." Roehrs went to work for an orchid grower, but just five years later, he founded his own nursery business, the Julius Roehrs Company, where he grew and imported flowering plants for the florists of neighboring New York City. His business was located on 17 acres in East Rutherford, New Jersey, and he transported his plants to New York City in horse-drawn wagons on the Hudson Ferry.

Roehrs died in 1913, just two years before a ban was placed on the importation of plants grown in soil. Little did he know that this would cause many plant importers to become growers at a time when tissue culture was a known method of propagation but was not widely used due to its cost and to so many failures to make the process work reliably. But, only a few decades later, in the 1940s and 1950s, tissue culture would be widely used in farm crops, along with other forms of propagation, and tissue culture would become the future of interior landscaping. By that time, Roehrs' business was still thriving and in the hands of his children in New Jersey, but the main growing operations of the tropical plant industry at large were gradually shifting to Florida, where they remain to this day.

At the time of Roehrs' death, his business consisted of 100 greenhouses and 100 acres of growing fields, all run by 200 employees. His daughter Anna married Carl Hoffbauer, and that family still runs the business today, now located in Farmingdale, New Jersey.

Roehrs' grandson, also named Julius Roehrs, sold nursery stock for the company in 1928, right after he graduated from high school. This was during a time when greenhouses were warmed by wood-burning heaters in winter and kept cool with ice in the summer. It was also a time during which Julius dated a woman named Janet Craig, for whom the Dracaena "janet craigii" is named! The company had problems during the Great Depression of the 1930s, but by the late 1940s and early 1950s, there was a boom in the use of house plants in office lobbies and other public spaces, and business was looking up. Julius worked as a sales representative for many nurseries over the years, and in 1964, he went to work for Keeline Wilcox, growers of kentia palms in Santa Barbara, California. He soon became known by the nickname "Mr. Kentia," due to his great knowledge of that plant. When Julius passed away in 1992, it was a great loss to the interior landscape industry.

The Roehrs enterprises not only grew plants, but also published books by tropical plant authority Dr. Alfred Graf. Graf came to the United States and went to work for his fellow German, Julius Roehrs (the elder). It was Graf who pointed out that plants in the office appeared to have originated with the employment of women in the workplace. He noted that women brought flowers in to decorate their desks, and from that modest beginning grew the tradition of having plants in the workplace.

While employed by Roehrs, Graf wrote several books that Roehrs published, including "Exotica," "Exotic Plant Manual" (which spawned the much smaller "Exotic House Plants"), "Tropica," and "Hortica" (from which the author of this article named her publishing business and this Web site). Graf returned to Germany and died there in 2002 at the age of 100. His encyclopedic works featuring photographs of plants, many of which were captured on camera in their native countries of origin, are still definitive references found in the libraries of many interior landscape companies.


In the early 20th century, indoor gardening became far less popular than in the previous century. Although the electric light had been invented by that time and was therefore providing superior illumination in comparison to gas lighting, central heating had lowered the humidity of indoor environments, and that made it more difficult to maintain plants indoors. About the only plants that could still be effectively grown indoors were palms, and you could only have so many of them in one house. Foliage plants were also difficult to obtain during that time and cut flowers were inexpensive substitutes.

During the 1930s and the Great Depression, houseplants again experienced a revival, this time in the form of dish gardens. Some homes had a few plants here or there, but the lushly adorned indoor gardens of the previous century were still a few decades away. The interior landscape industry didn't really start in earnest until the late 1940s.


One of the earliest founding leaders of the interior landscape industry was Everett Conklin, a traveling salesman who founded Everett Conklin & Co. and sold potted plants and flowers out of his New Jersey nursery. After his son joined the business in 1963, they started doing installations and maintenance. Conklin's first big interior landscape installation was the Four Seasons Restaurant in New York City, followed by the Ford Foundation, CBS building, Rockefeller Center, and many other large corporate clients.

When the 1970s rolled around, the interior landscape industry was really in its infancy, and Conklin was one of the largest interiorscape companies in the United States. The company specialized in shopping malls and hotels, and Conklin believed that the key to a successful installation was the acclimation of plants to low light levels prior to installation. In 1972, he was president of the Society of American Florists and was making news. He and his colleagues had formulated a theory that humans were genetically programmed to require surroundings of green, growing plants. In an address made to the American Society of Horticultural Science, he suggested that the man-flora relationship was an inborn link going back to the beginning of man.

Conklin was very active in many trade associations, and he was also a program advisor for the Department of Agriculture. Known as the "father of interior landscaping," Conklin died in 1985 at the age of 77.


Another important leader in the interior landscape industry was Robert Herrick Carter. Carter was a teenager in the early 1940s when he first began maintaining plants in the lobby of a Los Angeles building where his mother worked. He graduated from the University of Southern California (USC), went to work in the landscaping business, and became one of California's first licensed landscape architects. He was still maintaining that lobby planting — and others as well — when he founded Van Herrick's Environmental Planting, an interior and exterior landscape company in southern California. He also founded Pacific Plantation Growers in Hawaii and Pacific Foliage in Escondido, California.

One of Carter's first big projects was the design and installation for the Los Angeles Museum of Art. He designed and installed many other world-class interiorscape projects in the Los Angeles area, and Van Herrick's earned more than 50 design awards. Carter is probably best known for pioneering the practice of leasing plants at a time when most companies were content to sell them outright. He died in 1991, almost 50 years after he first started maintaining those lobby plants as a teenager.


In the 1970s, the interior landscape industry took a giant leap forward as the trend for indoor plants grew, and seemingly everyone wanted plants in their homes and offices. Anyone with a green thumb and a water bucket was "in business." It was the era of the "plant lady" and the "plant man." Macramé hangers, decorative baskets, and palm trees were sold on street corners by enterprising "hippie" types.

In 1972, the office management committee of the Association of School Business Officials was studying the concept of the landscaped office. And, the following year, the Journal of Applied Psychology (JAP) published the results of a study on office landscaping which reported that 600 government workers expressed greater job satisfaction, more effective communication, and greater productivity in a plantscaped office. By 1979, the concept of plants having a positive effect on workers was still being studied, and the JAP published another article detailing a study in which subjects rated how they would feel seated in different offices, some with plants, some without. The presence of plants led to positive responses, particularly with female subjects. Later that same year, a study of institutionalized people revealed that indoor gardening was a very manageable therapy for mentally and physically challenged patients.

The 1970s was also a time when the energy crisis was forcing builders to turn to more energy efficient products for construction. These materials were largely carcinogenic and contained, among other things, the EPA's top three culprits: trichloroethylene, benzene, and formaldehyde. The use of these toxic materials led to a multiple-symptom disorder in people that became known as "sick building syndrome." Could indoor plants be a solution to the problem? One man thought so.


Dr. Bill Wolverton was a senior research scientist at NASA's Stennis Space Center in Mississippi for 18 years. In 1973, NASA discovered that Sky Lab 3 was contaminated with over 100 chemicals, and Wolverton was called in to solve the problem. He later experimented with ways to use common house plants as filtration and oxygen-producing tools for extended exploratory, manned voyages into outer space. Sounds kind of Star Trek-ish, but as a result of his studies, Wolverton became one of the world's foremost authorities on the use of natural plant processes as a means of controlling indoor environmental pollution.

By the early 1980s, Wolverton had become famous for his "plants for clean air" studies and was known for calling plants "the lungs of the earth." He found that some plants worked better than others as air purifiers, and he discovered that not only did the plants themselves purify the air, but the soil also removed pollutants from the air. In 1984, he published his research, and the following year, he published another similar paper which emphasized the removal of carbon monoxide and nitrogen dioxide from the air. In 1989, his report on interior landscape plants for indoor air pollution abatement was published by NASA. That same year, he perfected the first combined indoor air and wastewater purification system, which he installed in his home in Picayune, Mississippi.

Wolverton recommends 2-3 plants per 100 square feet, and advises that the easiest to grow and most effective plants at removing indoor air pollutants are: spathiphyllums, areca palms, lady palms, Ficus alii, and the golden pothos.

Wolverton has published more than 70 technical papers and has received numerous patents and awards, including one as Federal Environmental Engineer of the Year for 1983. He was also one of the first five inductees into the U.S. Space Foundation's Space Technology Hall of Fame. He retired from NASA in 1990, but continued to do consulting work for that agency. Wolverton's clean air studies resulted in an enormous marketing opportunity for the interior landscape industry, as they could now sell plants not just as decorative items, but as a healthy solution to sick building syndrome. His most recent book is entitled "Eco-Friendly House Plants" (2010, Viking Press).


The 1980s was a time of enormous growth for the interiorscape industry. In 1986, there were approximately 8,000 interior landscape companies throughout the United States, many that were one- or two-person operations, and there were about another 8,000 non-U.S. interior landscape companies. It is now known by many as the "Decade of Greed," but the 1980s was also the decade of atriums, malls, and airports — the mega-installations. These huge projects required a new approach to installation and maintenance owing to the types of plants being installed and the necessary access by technicians to maintain them. Technology was revolutionizing the expanding industry, beginning with more widespread use of such high-tech products as pressurized watering tanks and subirrigation systems.

The 1980s also brought strong evidence that the proximity of plants was important for maintaining the highest level of functioning for humans. In 1982, an article in HortScience by P.D. Relf encouraged major contributions to the research of people-plant interactions. The results of a study on plants and thermal comfort in the indoor environment was presented at the Factors Society's 27th Annual Meeting. It revealed higher comfort ratings in the spaces in which plants were used.

Irrigation technology gained acceptance during the 1980s. The Mona or MPS Capillary Irrigation System is still the most widely used subirrigation system in the world, and can be used indoors or outdoors with its system of flexible, linking reservoirs. The economical Jardinier system was designed to conserve water and was also used in built-in planter beds, and the Everlife system, similar to Jardinier, was developed by growers who sold their plants in those containers. Unfortunately, the Jardinier and Everlife systems are no longer manufactured. The only fully-enclosed subirrigation system that requires no measuring or special skills to maintain is the Natural Spring Controlled Watering Planter.


In the late 1970s, Allen Secrest had been hired to launch a "self-watering" planter that had never worked properly. His employer went out of business as a result. But Secrest liked the idea and he stuck with it. He traveled to Japan and bought the molds for these subirrigation planters that had been developed but never used. They worked on the basis of capillary action, and Secrest dubbed them "Natural Spring Controlled Watering Planters." He founded Planter Technology in Mountain View, California, and tried to sell his Natural Springs to home owners and hobby gardeners. It didn't catch on. Not to be deterred, he turned instead to the interior landscape industry. They were not all that receptive either — at least not at first. I was at a conference in about 1981, where Secrest and an associate introduced Natural Springs to a less than enthusiastic audience of southern California interior landscapers who almost unanimously expressed concern that a plant that could water itself would likely put them out of business! But 25 years later, there were more than 30,000 projects worldwide that were installed with the award-winning Natural Spring containers. Secrest sold Planter Technology in 1995, and the company is now located in Hayward, California, and operates under the name Tournesol Site Works.


If the 1980s was a time of growth, the 1990s was a decade of shrinkage. The industry dropped into a recession as small companies either merged or were bought out by large corporations, mainly the British company Rentokil and the American Orkin corporation. Some of the smaller franchise businesses managed to grow, such as Foliage Design Systems and John Mini.

In 1991, American Nurseryman magazine published an article by P.D. Relf which described the various kinds of positive effects that plants have on people and noted the different studies made of people-plant interactions. The Plants for Clean Air Council began releasing frequent updates on Wolverton's ongoing research. The increased support from the horticultural industry and the academic community with regard to people-plant research encouraged greater interest from the scientific community and, as a result, the 1990s proved to be the start of a new era in interior landscaping.

At the beginning of the 21st century, the industry bounced back with a new and more professional approach to interior landscaping, partially owing to the fact that consumers had fully accepted the role of plants in the indoor environment. It was much easier to convince a client to have plants when so many studies had been done that indicated the positive effects of plants on people working in offices, as well as on populations in hospitals and even in prisons. People were shown to have a positive psychological response to plants. Plants could bring joy and happiness to a home, were used to cheer up the sick, and were considered a therapeutic activity for invalids. People liked plants and had feelings of well-being and a reduction of stress associated with landscaped interiors. Then there was the physical-chemical effect on the indoor environment with the purification, humidification, and temperature control (from shading and evaporative cooling) that plants provided. And in noisy offices or on busy streets, there was the acoustic improvement that plants produced by absorbing and thereby dulling noise and reducing the stress of noise pollution.


As of the latter part of the first decade of the 21st century, the interior landscape industry was broken down pretty much the way it was when this article was first written and published back in 1986:

- Growers are located primarily in Florida, which accounts for approximately 45% of all growing of tropical plants. Other large growing markets include California (15%), Hawaii (10%), and Texas (10%).

- Interior landscape companies in the United States find their biggest markets in California (25%), Florida (15%), Texas (15%), and New York (12%). These tend to parallel the grower locations, which are in preferred climates for the most economical growing conditions.

- Interior landscape markets outside of the United States are Australia, Malaysia, and Africa (primarily South Africa). The market in Europe is small but viable, and South America is likewise a small but viable market.


Indoor plants are often called "exotics," "tropicals," "foliage plants," or simply "house plants," and they account for less than 1/1000 of a percent of all known plants. In their native habitats, many grow in the semi-shade of rainforest canopies, which makes them well-suited to living in the lower light levels of our indoor environments. Many of today's interior plants originated in Africa, New Zealand, Australia, Central America, and other tropical and subtropical regions. For years, horticulturists have been going on "plant safaris" to some very remote parts of the world where they seek out likely plant specimens that grow in filtered light and shade and are hardy enough to be grown for commercial use in the interiorscape environment. One such horticulturist is Dr. Charles Sacamano of the University of Arizona, Tucson. Sacamano's plant safaris to the jungles of Mexico have been well-documented in articles and also in film, such as "Secrets of the Selva," which was broadcast on TV and was also released some years back as a videotape called "Plant Hunting In A Lost World."

But, after all that effort in finding these plants, and after they are brought back to the United States, they must be reproduced and grown in greenhouses and later acclimated to grow under less ideal conditions, such as those found in homes and offices. This is a long process which takes about two years or more to complete. And, of the many new plant varieties brought into the United States, only about 20 to 25 percent actually survive. The plants which are chosen for development are selected based on the response of consumers. Everyone has decidedly different tastes, but most consumers prefer plants that are not overwhelming in size. For this reason, growers work at developing plants with elaborate foliage and a small, compact shape.

Most of the plants we use in the interior landscape today are not native to the areas in which they are currently being grown, and most of the plants being grown for sale are not found in nature at all. Today's interior plants are bred in greenhouses to be more colorful and attractive, to live in artificial environments, to be more resistant to pests and diseases, and to be more tolerant of low lighting conditions. While they are primarily grown in tissue culture labs, and while they are less hardy than outdoor plants, today's cultivated interior plants are in most other ways physiologically the same.


So what's new in the interior landscape industry of the 21st century? Green or living walls, of course! Living walls are a form of urban gardening built both indoors and outdoors. They are essentially vertical gardens in which plants are rooted in fibrous material, with the water being reused and/or recirculated. The systems vary in the sophistication of their construction. Some living walls are pre-grown while others are planted on site. One system, the ELT Easy Green Living Wall, contains panels made of 100% recyclable black high density polyethylene, making the plastic UV stable and resistant to chemical fertilizers. The system is designed so that water flows through the panel via a series of grooves that ensure complete saturation, leaving a small reservoir of water to prevent drying out. Water is applied from the top with a hose or a drip tray.

As you can see, a lot has happened over just the last 100 years or so. The interior landscape industry has come a very long way from the ferns and cast iron plants of the Victoria era. Where will we be ten years from now? Twenty years from today? It's hard to say, but we can be sure our industry will continue to expand into all things new, exciting, clever, and good for people and the environment.

This article last updated: 01/13/2001.