Question of the Week: November 16, 2017

“Neil, will it protect my grass from winter’s cold if I leave tree leaves in place over it?”

To leave or leave not – that is the question…
You may have heard me recommend using fallen tree leaves as a mulch to cover and protect the root systems of shrubs and perennials. You may have wondered if that same theory might apply to lawngrasses.

I’ll carry that one step farther. You may have noticed that grass remains green beneath the layer of tree leaves, so the mulch is obviously doing its job at “protecting” the grass.

So is it a good idea to leave the leaves in place on the lawn?

No. It is not. And here are my two main reasons.

1. Not only is warmth trapped beneath the layer of leaves, but so is moisture. The surface is sheltered from the movement of air across the grass, so it doesn’t dry out. And most of us learned a long time ago (perhaps through wet laundry in the hamper) that warmth plus moisture equals mildew and mold. Grass that is covered with leaves is far more likely to come down with diseases.

2. Leaves have a habit of moving around. When the winter wind blasts through, it’s likely to blow the leaves off the grass suddenly exposing it to cold temperatures. St. Augustine is especially vulnerable. It’s sensitive to freeze damage in the northern parts of its range anyway, and when we see its protection becoming airborne we’re just asking for trouble.

 

And other factors…
• Leaves are unsightly, so the neighbors probably aren’t going to appreciate your leaving them to blow down the street.

• In extreme situations, those leaves can even become fire hazards as they pile up against fences and structures.

• Eventually you’re going to have to mow and mulch or bag the leaves anyway, so you might as well do it now and put them to use in your landscape beds or in the compost. They’re a natural resource worth saving.