Marin Master Gardeners
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Marin Master Gardeners

Marin IJ Articles

Houseplants Part 1

January 16, 2012
Nanette Londeree

Bringing the green in to stay

If you enjoy bringing fresh-cut greens 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, creating a sense of colorful coziness, along with the added bonus of purifying the air you breathe. Low cost, decorative, sun-powered air filters—what could be greener than that?

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. According to the U.S. Environmental Protection Agency, we Americans spend about 90% of our time indoors—that’s a lot of exposure to those undesirable pollutants. Just as trees are vital to the health of our outdoor environment, purifying the air and producing valuable oxygen for us to breathe, indoor plants perform the same beneficial functions on a smaller scale.  

A study done in the late 1980s by the National Aeronautics and Space Administration (NASA) together with the Associated Landscape Contractors of America (ALCA) found certain houseplants were able to remove as much as much as 87% 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. Chances are, all houseplants provide some level of air purification.

Houseplants come in a huge range of sizes, forms, colors and textures. Many originate in tropical or sub-tropical forests growing well under the canopy of taller trees—relatively low light conditions similar to our indoor environments. Successfully growing 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 us, 60-75?F, also work for most indoor plants. Just keep them away from heater / air conditioning vents, heat-generating appliances, fireplaces or drafts. Humidity is more of a challenge running, on average, around 10-30% in most heated spaces, while plants native to more humid climates thrive in 30-70% 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 half way with water.  You can also mist plants regularly using a water-filled spray bottle.  

Houseplants that I’d describe as easy to grow are 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. I’ve been growing houseplants for decades and have experimented with oodles of varieties in lots of different conditions. My top ten include:  

  • The cast-iron plant (Aspidistra elatior), a favorite of the Victorian era when houses were far from bright and airy, 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) are a group of durable foliage plants 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, vine-like foliage. They withstand neglect and poor conditions and keep right on growing.
  • Golden pothos, also called devil’s ivy (Epipremnum aureum) is a hardy plant with fleshy, golden to ivory, variegated heart-shaped leaves on long, trailing stems that can grow to eight feet or more.  
  • The umbrella tree, Schefflera actinophylla with glossy oval leaves that appear like little umbrellas at the ends of branches, can grow to six feet tall or more. A dwarf variety, Schefflera arboricola, is a smaller and bushier plant.
  • A member of the agave family, the snake plant or mother-in-law’s tongue (Sanseveria trifasciata) does well in very dry conditions. The striking deep green, erect, strap-shaped leaves, laced with bands of lighter green or yellow, grows 18-30 inches tall.  
  • Dracaenas (Dracaena species) are leafy members of the lily family with a broad range of sword-shaped, slender leaves; many striped cultivars display jewel-toned colors.
  • The sweetheart plant or heartleaf philodendron (Philodendron scandens) is another vining plant that stays small and is exceptionally drought-tolerant.  
  • A great choice for hanging baskets, the spider or airplane plant (Chlorophytum comosum) sports rosettes of long, green and creamy white variegated leaves. It produces baby plants at the end of long stems that are easily propagated.
  • The graceful Boston fern (Nephrolepis exaltata ‘Bostoniensis’) with long, arching fronds densely covered with leaflets, is not an overly fussy plant if given the right conditions; humidity is the key for keeping this gorgeous plant happy.  

Note: Plant names in bold are varieties included in the NASA study and proven to reduce organic chemical pollutants.

So, bring in nature’s air purifiers—choose some houseplants that fit in your environment, provide them with basic care and you’ll add beauty and life to your indoor spaces, and breathe a bit easier as well.

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