The Carlisle Mosquito Online

Friday, February 15, 2002


There's time for indoor gardening in February

There isn't a lot of gardening to be done in February. As much as you would like to clean up the sticks that have blown down, or wander around cutting the ragged stems of hardy chrysanthemums that are poking out of the muddy ground, it just isn't the right time yet for spring cleanup. It is still winter. Gardeners are stuck indoors, in the dry desert climate of heated homes, breathing the closed-in air of the winter house. But luckily there is one form of winter gardening that can brighten up your spirits and help you breathe easier. February is the perfect time to give attention to those hardworking houseplants hanging in your window and sitting on your hall table. By giving attention to your houseplants, you will be enhancing your own air filtration system.

Houseplants clean indoor air

A 1984 NASA study performed by researcher Dr. Bill Wolverton showed that many common houseplants are capable of purifying the air of indoor pollutants. Dr. Wolverton's study tested for three common pollutants: formaldehyde, found in such items as particleboard, paper towels, facial tissues, grocery bags, waxed paper and plywood; benzene, contained in rubber, paints, gasoline and inks; and trichlorethylene (TCE), found in paints, varnishes, and dry -cleaning fluids. These chemicals can irritate eyes, throat and nose and cause headaches and dizziness. Prolonged exposure can cause memory-loss, liver and kidney damage and they are potential carcinogens.

Old houses purified themselves

Before the 1970s houses were built like sieves: air freely exchanged every few hours through poorly insulated windows and doors. After the energy crisis of the seventies houses became super-insulated to lower heating and cooling costs. Air that might exchange every few hours instead remained stagnant possibly for a full day, allowing pollutants to accumulate.

Cases of asthma have risen, and "sick building syndrome," in which a whole building is contaminated with out-gassing chemicals, has been increasing.

Photosynthesis and soil microbes

Plants take in carbon dioxide and release oxygen, a process called photosynthesis. While the plants produce their food, they clean out the air by absorbing carbon dioxide, as well as other pollutants. Some pollutants are transferred to the roots of the plants, where they are broken down into harmless chemicals, taken as food for the plants or released into the soil. Microorganisms in the soil use the toxins for food, and the roots absorb their waste process.

Take advantage of houseplants

You are probably already cleaning the air in your house with those tired looking spider plants in the window. You can use this cleaning system anywhere in your house. But you need to give something back to your plants. Your houseplants are dormant right now and don't need fertilizers until March. But February is the perfect time to give them fresh soil and new pots, discarding old leaves. After replacing the soil, check on the humidity of the room they live in. Most likely it is dryer than a desert. You can help your plants by placing them on a small dish, filled with flat stones, and filling the dish with water as often as you can remember. Be sure the water does not reach the bottom of the pot. As the water evaporates, it increases the humidity around the plant.

Ideal plants for air cleaning

Although all plants will cleanse the air, certain plants are over-achievers in vacuuming toxins. Areca palm (Chrysalidocarpus lutescens), chrysanthemums, philodendron, poinsettia, and spider plant (Chlorophytum comosum) will remove formaldehyde. Plants such as English ivy (Hedera helix), dracanena marginata, peace lily (Spathiphyllum wallissii), snake plant (Sansevieria trifasciata) and gerbera daisy were shown to clean benzene and trichlorethylene from the air. The NASA study recommends 15 to 20 plants for a typical 1,800-square-foot house.

Plants bring the outdoors inside

Some skeptics say that thousands of plants would be required to make an impact on a building with "sick building syndrome" and point to the controlled conditions in the NASA study as the reason for the remarkable results. The best reason to have houseplants is to enjoy their beauty, and to bring a piece of the outdoors into our homes. Gardening with houseplants can lower stress levels, and possibly lower the air pollutants in our homes. Giving our houseplants a little attention in February seems like a reasonable price to pay. They make our homes a brighter and more pleasant place to wait for spring.

2002 The Carlisle Mosquito