Bad Habit #11

Landscape Fabric  

It’s a myth that landscape fabric prevents weeds.  Yes, they may initially, however, the fabric, once down, tends to stay in place season after season and that’s where trouble starts.  Issues include:

Weed seeds blow on top and germinate in the mulch layer sinking their roots down thru the fabric making it/them hard to remove. 

The roots of desired plants grow across and on top of the barrier.  Thus, they are not as deep in the soil as they should be.  The lack of deeply penetrating roots make the plant easily toppled by high winds and very susceptible to drought.  We want to encourage, not discourage, deep root growth. 

Landscape fabric prevents plants from spreading and naturalizing in your bed.  Worse, weed barriers are also sometimes impregnated with herbicides and fertilizers.

A major drawback of the practice is that it inhibits soil building.  When mulch is applied over the fabric it can’t decompose and contribute to building the health of the soil beneath it.  Many of the old weed fabrics aren’t water and gas permeable leaving the soil beneath dry and compacted.  This starves plants for water and nutrients and results in greatly reduced soil food web activity, noticeable by a lack of insect activity and earthworms.   When used on areas that hold on to excess water and become soggy, the weed barrier can trap water beneath it, creating a swampy mess, and a perfect breeding ground for some noxious weeds (e.g. field horsetail). 

A final observation is that many are plastic films, and you know what we think of plastic!!  They eventually break down and you find bits of plastic everywhere.  Landscape fabric is really hard to remove once it starts breaking down and depositing microplastics in the soil.  The long-term implications of the excess of microplastics in our ecosystems are yet to be fully defined, but we suspect that they are not good. 

Kick the Habit There is no magic solution that will eliminate weeds.  Apply mulch, more mulch, and more mulch still.  Wood chips, leaves, other organic materials such as pine straw and compost all will do a better job while eventually breaking down and building your soil.  Even stones and pea gravel are better.  Layer your mulch 2-3″ thick and very few weeds will get through.  Better yet, use a living mulch of native ground covers to outcompete the weeds and reduce the need to add brown mulch each season.  In summary, landscape fabric offers a short-term gain in return for a long-term problem.