Editor’s note:
This is the first installment of a two-part series about houseplants.
IF YOU ENJOY bringing greenery indoors for the holiday season, reveling in the array of tones and textures that pulls the lush feel of the outdoors inside for a few short weeks, you can keep that feeling going year-round with a few well-placed houseplants.
Houseplants can create a sense of colorful coziness, and they also come with the added bonus of purifying the air. Low cost, decorative, sun-powered air filters — what could be greener than that?
According to the Environmental Protection Agency, Americans spend about 90 percent of our time indoors — that’s a lot of exposure to those undesirable pollutants. As today’s homes, schools, offices and public buildings are tighter and more energy efficient than ever, they can trap potentially harmful organic chemical pollutants commonly emitted by paints, cleaning supplies, building materials and furnishings, dry-cleaned clothing and more.
Just as trees are vital to the health of our outdoor environment — purifying the air and producing valuable oxygen to breathe — indoor plants perform the same beneficial functions on a smaller scale.
A study done in the late 1980s by NASA with the Associated Landscape Contractors of America found certain houseplants were
able to remove as much as 87 percent of indoor air pollutants within 24 hours.
Of the plants evaluated, researchers came up with a list of easy-to-grow houseplants proven to reduce the most prevalent organic contaminants — formaldehyde, benzene and trichloroethylene — that included plants such as:
Philodendron scandens “oxycardium,” heartleaf philodendron
Dracaena fragrans “‘Massangeana,” cornstalk dracaena
Hedera helix, English ivy
Chlorophytum comosum, spider plant
Ficus benjamina, weeping fig
Spathiphyllum “Mauna Loa”, peace lily
Chances are, however, all houseplants provide some level of air purification.
Houseplants are available in a huge range of sizes, forms, colors and textures. Many originate in tropical or subtropical forests growing well under the canopy of taller trees — relatively low light conditions similar to our indoor environments. Successful cultivation of houseplants starts with choosing the right plant for the location (adequate light, temperature and humidity), planting in healthy soil in an appropriate container, then keeping it in shape with watering, feeding, grooming and pest management.
The amount and duration of available light plays a vital role in success with houseplants. Light intensity, or brightness, ranges from low, typically found near a north-facing window to high, up to five feet away from a southern window. The brightest is direct light, likely found right in front of a window with southern exposure. Light intensity varies with the seasons, with more indoor light in winter. The duration of light, the number of hours of light per day a plant receives, is likely to be much less in winter than in the summer.
Comfortable temperatures for people, generally 60 to 75 degrees, also work for most indoor plants. Just keep them away from heater or air-conditioning vents, heat-generating appliances, fireplaces and drafts.
Humidity is more of a challenge, running, on average about 10 to 30 percent in most heated spaces while plants native to more tropical climates thrive in 30 to 70 percent humidity. You can increase the humidity around plants by grouping them together or setting the plant on a saucer filled with crushed stone and covering the stones halfway with water. You can also mist plants regularly using a water-filled spray bottle.
Houseplants described here are easy-to-grow ones that do well in low light, tolerate dry conditions (water and air), require little maintenance (re-potting, primping or pruning), and are fairly resistant to pests and disease. Some of the varieties, which also were included in the NASA study, are proven to reduce organic chemical pollutants.
The cast-iron plant (Aspidistra elatior): A favorite of the Victorian era when houses were far from bright and airy, it is one of the most carefree plants you can grow, surviving with very low light and general neglect. This slow-growing tidy plant, with big, bold, emerald-green leaves, is nearly indestructible.
Chinese evergreens (Aglaonema species): A group of durable foliage plants the come adorned with dramatic silver and green, lance-shaped leaves, they perform well even in dim light (though leaf markings will be bolder in brighter light) and prefer being slightly pot-bound, so rarely need repotting.
Members of the grape family: The kangaroo vine (Cissus antartica), oakleaf ivy (C. capensis) and grape ivy (C. rhombifolia) are ideal for locations where they can drape their rather delicate-looking, vinelike foliage. They withstand neglect and poor conditions and keep right on growing.
Golden pothos (Epipremnum aureum): Also called devil’s ivy, this hardy plant grows fleshy, golden to ivory, variegated heart-shaped leaves on long, trailing stems that can grow to eight feet tall or more.
The umbrella tree (Schefflera actinophylla): With glossy oval leaves that appear like little umbrellas at the ends of branches, it can grow to six feet tall or more. A dwarf variety, Schefflera arboricola, is a smaller and bushier plant.
The snake plant or mother-in-law’s tongue (Sanseveria trifasciata): A member of the agave family, it does well in very dry conditions. The striking deep green, erect, strap-shaped leaves, laced with bands of lighter green or yellow, grows 18 to 30 inches tall.
Dracaenas (Dracaena species): Leafy members of the lily family develop with a broad range of sword-shaped, slender leaves; many striped cultivars display jewel-toned colors.
The sweetheart plant or heartleaf philodendron (Philodendron scandens): This vining plant stays small and is exceptionally drought-tolerant.
The spider or airplane plant (Chlorophytum comosum): A great choice for hanging baskets, it sports rosettes of long, green and creamy white variegated leaves. It produces baby plants at the end of long stems that are easily propagated.
Boston fern (Nephrolepis exaltata ‘Bostoniensis’): With long, arching fronds densely covered with leaflets, it’s not an overly fussy plant if given the right conditions; humidity is the key for keeping this gorgeous plant happy.
Next week, I will delve into watering, fertilizing, pruning and pest control with houseplants.
So, add some beauty to the indoors and bring in nature’s air purifiers by choosing some houseplants that fit in your environment. You’ll breathe a bit easier as well.
The University of California Marin Master Gardeners are sponsored by UC Cooperative Extension. For questions about gardening, plant pests or diseases, call 499-4204 from 9 a.m. to noon, and 1 to 4 p.m. weekdays, or bring in samples or pictures to 1682 Novato Blvd., Suite 150B, Novato.