What once was simply called a houseplant is now an essential part of interiorscaping--the practice of landscaping indoors. Working parents and their video-gaming children spend large percentages of their lives in buildings made more habitable by central heating, air conditioning and modern building codes. Interiorscaping provides a natural environment for office buildings, malls and schools. The plants in these special landscapes need special care.
Plants help provide a natural environment, soften hard surfaces, and aid in decorating large spaces. They also provide a service, according to National Aeronautics and Space Administration scientists who conducted a study that found that using plants in large numbers not only generated oxygen but also broke down several toxins. The toxins tested included benzene, trichloroethylene and formaldehyde, all common out-gassing products of modern building materials that become trapped in efficiently sealed buildings.
Place plants used in interiors in groups with similar cultural requirements. Plants that require different temperatures, humidity, fertilizer or moisture and light levels will either crowd each other out or weaken due to improper treatment. Each group should form its own mini-environment in an area separate from others. Fast-growing, large-leaved tropical plants are attractive and make the best oxygenators, but some interiorscapers choose slow-growing plants so they have to replace overgrown plants less often. Others choose plants that will not outgrow their location. All plants will eventually need to be "changed out" and returned to a greenhouse or outdoors for a "vacation" to regain full vitality.
Water and Light
A programmed in-ground irrigation system waters areas precisely and efficiently in large interiorscapes. Skylights and atriums provide enough light for many interiorscapes but fluorescent and incandescent lights are also necessary to supplement winter sun or provide light for enclosed spaces. Water plants until water runs through the planting medium to keep fertilizer salts from forming a crust on the surface.
Soil and Fertilizer
Provide a growing medium that is porous so that roots do not rot but will retain moisture and nutrients for interiorscapes. Artificial soil-less mixes contain high percentages of peat moss and perlite, and are mulched with sphagnum moss and shredded bark. Choose fertilizers for the variety or cultivar of plant; a 20-20-20 fertilizer mixed half-strength and applied twice a month during the growing season keeps most plants healthy.
Diseases and Pests
Interiorscapes are little worlds, and disease or pests can spread quickly. Diseased plants should be removed from the area for nursing back to health or disposal. Large interiorscapes like those at the Mall of America in Minnesota become complete environments when beneficial biological controls or predator insects like soft scales are used to control common pests like aphids, scale, mealybug, whitefly and thrips. Other interiorscape gardeners use insecticidal soap and pesticides designed for indoor use. Badly infested plants, though, must be pruned back, removed for dipping and re-potting, or bagged and discarded before they infect others.