After two weeks of municipal strikes, the wheelie bins lining the roads are starting to bulge . . . and smell. There’s one plus to this, however. Since the surplus of refuse is literally lifting the lids of the bins, I’ve been able to get an easy look at what people are throwing away. To a large extent, they are throwing away greens. And there’s nothing green about that.

One of the most dangerous myths about the environment is that it is better to send something biodegradable to a landfill than something that will last a hundred years, like a plastic bottle. Quite frankly, that’s a load of garbage.

The last thing you want to happen in a landfill is biodegradation. Deep in a landfill, in the absence of oxygen, bacteria break down plant material into methane. This gas is 21 times more potent as a greenhouse gas than carbon dioxide. If garden waste is composted or left to decompose in the garden, it will give off carbon dioxide, but only as much as it absorbed when it was growing. So sending plants to the landfill is 21 times worse for the atmosphere than composting them.

Grass clippings are the worst, since they decompose much faster than, say, twigs. It is impossible to precisely calculate these things, because of the many variables in landfills, but a reasonable estimate based on a thorough scientific report, is that 1 kg of garden waste in a landfill will give off 77 grams of methane. This means that a full, standard black refuse bag (750mm x 950mm) containing  14 kg of grass clippings will give off as much greenhouse gasses as burning 9.5 litres of petrol by driving nearly 100 kilometres. Recycling the equivalent quantity of plastic—the same bag filled with 3 kgs of empty PET plastic bottles—would save less than a sixth as much greenhouse gases as composting that bag full of grass.

Our lawn space is considerably smaller than many suburban gardens. But my gardener says that in the summer, he mows about two bags worth of clippings twice a week. So in some months, our grass clippings would be causing as much damage to the atmosphere as the electricity consumed by our house, if we were throwing these clippings out with the garbage.

But we don’t. I don’t have much energy for composting, so just a fraction of the clippings go into a somewhat neglected compost pile, which nonetheless manages to produce some good compost in time. The rest is stored in reusable large woven polypropylene bags until we have a carload. Then I haul them a couple of kilometres to the nearest Pikitup garden refuse transfer site, so the municipality can compost for me. It’s a small inconvenience to keep my grass truly green.

Six months ago, I launched an experiment to address this conundrum, and I am happy to declare it a success.

First an anecdote to illustrate how far apart my gardener’s mindset was from mine. Last summer, when we went away for two weeks, I took a chance that good rains would continue and shut off the sprinkler system. (I always shut it off in the summer whenever we have had 25 mm of rain in the past week.) When I returned to Johannesburg, I was delighted to see the city looking lush and green; I knew that my gamble had paid off. As I arrived at my house, however, I was appalled to find my sprinklers spraying full-blast. The next time I saw my gardener, he cheerfully reported that the day I left he had discovered that I had left the sprinklers off “by mistake” and that he had “fixed it” for me.

So when he later borrowed a couple thousand rand to buy materials to build his mother a house, I knew how I could help him pay it back. I showed him my water bills from 2006, and told him that we would follow the 2007 water bills and compare them. As long as the garden remained reasonably green, we would share 50/50 any money we saved on water.

The first change I noticed was that he was using a broom to sweep a brick walkway that he used to hose down. When he washed the car, he used a big bucket, instead of a running hosepipe. And where I had often found him watering parts of the garden that didn’t need it, he now asks first.

My water bills for the last six months have come down by an average of 38 percent, and my gardener’s debt has been cut by R670. I know that some of this is because the garden is more established now and needs less water. The good rains in October also helped. But I am convinced that a major reason is that we both share the same mindset now when it comes to water conservation.

I still have control over the sprinkler system, so the garden won’t go brown, and I know that he is too proud to let plants wither. But I have a hunch that the next time I shut off the sprinklers for a holiday, he won’t be fixing my mistake.