Grow Fresh Air With Houseplants

Here’s a statistic or two I’ll bet you’re not familiar with: According to the CSIRO, the average Australian spends approximately 90% of his/her time inside, where the air is often so polluted that the inevitable respiratory and other illnesses are estimated to cost around $12 billion annually.

And you thought we were infatuated with the great outdoors. It seems most of us are more in love with our flat screens than our backyards, and we’ll blithely spend about 22 hours a day breathing the Volatile Organic Compounds given off by our toxic indoor environment. How many of us realise that those VOC’s, compounds like formaldehyde and xylene, are carcinogenic or that a chemical cocktail of up to 300 different VOC’s could be found in something as innocuous as your lounge room, “off gassing” from the sofa, the paint, the carpet, and the walls? How many of us have suffered from the effects of Sick Building Syndrome (coughing, itchy eyes, loss of concentration) without realising it?

On the flipside, how many of us know that just a few houseplants in a room can remove up to 100 percent of these blasted VOC’s, with the bonus of added oxygen? It almost sounds too good to be true, but these are the findings from more than a decade of research by Professor Margaret Burchett.

A biologist at the University of Technology Sydney, Professor Burchett has found that it’s actually the micro-organisms in potting mix interacting with a plant that do the job of filtering toxins from the air. Professor Burchett has also found that you don’t have to live in an indoor jungle to greatly improve air quality. Just one 300mm pot plant in a room of 10sqm will make a difference, and three 300mm pots can reduce volatile organic compounds to negligible levels. Six smaller pots were found to be just as effective.

The other bit of good news from Professor Burchett’s findings is that the type of plant doesn’t really matter that much. Those used in the studies included typical houseplants like Draceana, Peace Lily, and the Kentia Palm, but findings indicate that almost any indoor plant will do the trick, as long as it has enough light and is healthy. Besides choosing shade loving plants you’re only really limited by your imagination.

What surprises me though is how many gardeners overlook the indoor environment. Maybe we’re so focussed on what’s happening outside the house that we forget that gardening can happen inside as well. In contrast, self proclaimed non-gardeners seem to love growing indoor plants and potted plants in general, possibly guided by the myth that because plants are inside, they are less prone to problems and harder to kill.

I don’t grow nearly as many houseplants as I should, but the one thing I’ve found over the years is that once you’ve taken care of a couple of essentials, well chosen indoor plants actually are a piece of cake to grow. Start with the basics. Choose tough species that come from shady, rainforest environments. Palms like the aforementioned Kentia or Rhapis are good,

Then, follow three rules of thumb. Don’t over water, do place your plants in bright indirect light, and do feed with a decent liquid fertiliser every few months during the spring and summer. The easiest way to kill any pot plant is by drowning its roots, so before reaching for the watering can, poke your finger in the potting mix. If it feels dry, water. If it’s moist, hold off for a bit. A drink three to five times per week is adequate for most indoor plants during summer, but you should then ease back to once per week or less during winter. And please, buy pots with decent drainage holes in them or drill some in the base.

Beyond that, all houseplants really need to thrive is a change of potting mix every few years. If pests become a problem, they’ll probably be insects of some description and these can generally be controlled with horticultural oil. Misting a couple of times per week does plenty of good as well, and on wet days, my wife insists that we carry the plants outside for a really decent soak in the rain. I usually complain, but she’s spot on. The plants appear to love it.

So come on gardeners. We already know how much plants contribute to general health and well being, and based on Margaret Burchett’s research, we ought to aim for at least a plant in every room. Office workers – grow a pot plant on your desk. Bosses – a plant or two will clear your head and help make you more productive. Filter those VOC’s. Produce some oxygen. It’s about time we started greening our offices and lounge rooms as much as the backyard.

First published in the Toowoomba Chronicle 23rd May 2009. Photo by Brett Hilyard.

Tagged as: House Plants, houseplants, inddor plants, volatile organic compounds