Lawns, Photosynthesis and Water

Again this year, the rain has been generous in my area (sometimes too much!) and most of our lawns are looking good. But we’ve also had some very nasty heatwaves, and the grass suffers a lot during these periods. But there’s one thing that’s essential for a good lawn: a high cut.

It can’t be repeated often enough: the longer the grass, the more vigorous it will be to produce long roots and survive periods of drought. It’s simple: plants grow through photosynthesis, a process that uses light energy and chlorophyll. So the greater the surface area of green leaves, the more organic matter, more leaves and deeper roots plants can produce. Grass surfaces should never be mowed lower than 8 cm (about 3 inches) in continental climates. The other very important factor is water, which is why lawns can be cut shorter in rainy maritime climates.

No Mowing in Hot Weather!

Many homeowners and most lawn care companies insist on mowing to 5 cm (2 inches) every week, even in hot weather. But when temperatures rise above 30°C (86?), most lawn grasses slow their growth. If the heat continues, the grass stops growing altogether and turns yellow. The lawn goes dormant. Cutting during such a stressful period can be fatal. On the other hand, a lawn left long, even up to 10 cm (4 inches) during a heatwave, will get through this stage without a hitch.

Why such an obsession with mowing at all costs every week? The desire to control nature? I’ve been told it’s cleaner. Is it? But lawns aren’t synthetic carpets!

Lawns in Intensive Care

Of course, it’s harder to play ball when the grass is long. In fact, soccer fields are always cut very short. But that’s intensive use, so it also requires intensive care: watering, aeration and other lawn pampering. In fact, to keep a soccer field looking its best, it shouldn’t be used for more than 25 hours a week, and that’s what is done with competition fields, which are often fenced off and intensively watered.

Aeration and topdressing are, of course, other ways of helping our lawns, but they’re more laborious. I recently discovered a company that offers hydric aeration, rather than coring, so as not to interfere with underground irrigation systems. I wanted to know what this miracle product was that aerated the lawn and was told that it was water with enzymes added to break down the thatch. So it’s not really a way of decompacting soil that’s been subjected to heavy traffic.

Golf Courses

I’d like to take this opportunity to say a few words about golf courses, which require even more care and water, especially for the greens, which are mowed close to the ground! But why do we insist on playing golf in regions like Arizona and even Saudi Arabia, where it almost never rains? Is it reasonable to draw on this resource, which is becoming increasingly problematic in some parts of the world? Technology can solve everything, of course, but at what cost to the environment? Why not adapt our pace of life and activities to an arid climate? Traditionally in hot countries, we take a siesta when the sun is at its zenith, and get busy in the morning and evening. And of course, golf was never played in a desert before the advent of luxury tourism.

A Few Statistics

In Quebec, water supply isn’t usually a problem, but we do use drinking water to water our lawns! But there are costs associated with treating and distributing all that water. Did you know that, at 260 litres/person/day, we are the world’s biggest consumers of water? (source: Government of Quebec)

By way of comparison, here are some eloquent figures on water consumption in various countries:

• Canada, USA, Japan, Australia, Switzerland: over 250 litres/person/day;
• Finland, Italy, Spain, Portugal, South Korea, Greece, Sweden: 160 to 250 liters/person/day;
• Denmark, United Kingdom, Austria, France, Luxembourg, Ireland: 130 to 160 liters/person/day;
• Germany, Netherlands, Belgium, Hungary, Bulgaria, Poland, Czech Republic: less than 130 liters/person/day;
• Asia and Latin America: 50 to 100 liters/person/day;
• Sub-Saharan Africa: 10 to 20 litres/person/day

(Sources Eurostat + Ifen + World Water Council).

Long Live Biodiversity!

Of course, another way to make our lawns better suited to our summer heat is to sow them with plants that are better adapted to drought and can withstand regular mowing, such as creeping thyme, clover, trefoil and various fescues found in low-maintenance mixes at garden centers. I’ve already talked about this in another article. Remember that late summer is an excellent time to overseed.