Indoor Plants Good, Bad and Ugly

As I’ve said before, indoor plants are a good thing. They are pretty, they make you feel happy, they overwhelmingly turn carbon dioxide into oxygen and they can extract nasty things from the air.

They also have their bad side, apparently. As well as removing what are called ‘Volatile Organic Compounds’ from the atmosphere, they also release some back again.

Research from the University of Georgia looked into the ‘VOC’ emissions of four potted plants - Peace Lily (Spathiphyllum wallisii), Snake Plant (Sansevieria trifasciata), Weeping Fig (Ficus benjamina), and Areca Palm (Chrysalidocarpus lutescens).

A grand total of 23 VOCs were released. Interestingly, some of the VOCs are part of pesticides that were applied to these plants during their early growth. Some VOCs came from micro-organisms living in the soil rather than the plants themselves (but remember the same micro-organisms are responsible for absorbing nasty VOCs as well). And 11 VOCs came from the plastic pots!

There were more VOCs released during the day than at night, with release seeming to be linked to the synthesis of at least some of these chemicals. How long the VOCs remain biologically active and whether they are deleterious to humans is not know.

But don’t let that put you off your indoor plants. They still absorb plenty of VOCs and as a recent study from Texas State University notes, us city folk spend more than 80% of our time indoors and plants help in ‘reducing tension, better coping mechanisms and increased concentration and attention’. They have also been shown to ‘reduce eye irritation and stress, motivate employees…a positive effect on headaches and fatigue and hoarseness, ...[reputedly] less dry skin…increase work productivity’. On the latter point, one study showed the presence of plants improved reaction time for computer tasks by 12%.

So obviously the next step is to plant out our classrooms (being careful to keep VOCs low…). This is exactly what the Texas University researchers wanted to test. For a whole semester they had some students studying amid tropical plants, and others in plant-less rooms. They also tested rooms with windows and those without. The student’s grades were compared at the end – along with lots of demographic data to check for other biases.

Sadly for the vision of Australian students peering out from tropical jungles, there were no differences in the grades or performance attributable to plants.. However the students amid the plants felt that the learning and enthusiasm of the teachers was higher. The lucky students who spent a semester in a windowless, stark room were not particularly satisfied when compared with the others. So it may be that plants can be a substitute for windows in making students feel a little cheerier and more positive, but they are no substitute for DNA and dedication to study it seems.

Image: this is my ‘ugly’ plant. It was the Christmas Tree (a seeding silver beet) in a student house I lived in many years ago...