Watching the Grass Grow in Our Swinging Weather

Post date: Apr 24, 2016 10:20:26 PM

The week April 17 to 23 this year saw some wild swings in temperature and humidity. Tuesday the temperature was up to around 80, the wind from the northeast, and the relative humidity was down to the around 11%. By Friday, the high was around 60 and it was raining. Now, when I look out at our close in defensible space, I see an odd mixture of green vigorously growing grass and tawny mature grass gone to seed. All of it is easily knee high. Ten days ago it was ankle high and uniformly green.

When I finish this posting, I’m going out to whack it all down to 4” or less. It won’t be easy with the tall green grass, but the tall dry grass makes it a high priority fire safe task. You see, when grass matures and goes from green to golden it is changing from a live fuel to a dead fuel. Dry grass is a one-hour fuel. In the simplest terms, it means that on a hot dry day when the relative humidity gets into the low teens and single digits, the dry grass is ready to burn in an hour. For more than you ever wanted to know about one hour to thousand hour fuels, see my post from last June.

In recent years, when we had less than half as much winter rain, I could put it off until late May and make a single pass, because the grass, with the exception of the seed heads just didn’t get that tall, but this year it looks like multiple passes with the string trimmer are going to be necessary over the coming weeks.