Wood Fence and Mulch, Two Woods That Don’t Work Together

So you got a brand new Gifford wood fence and you want to trim your yard with a nice boundary on the inside with maybe a few plants. If you have an irrigation system or get regular heavy rain, mulch is not the way to go. While it looks nice and it helps prevent weeds it will also hold all that daily moisture in, right up against your new fence. And yes this is even a problem for treated pine or usually wet tolerant wood species. 

The first factor in this scenario is irrigation. Here in central Florida we run our irrigation on an average of three days a week at around 45 minutes per zone. And unlike a rain shower that will be diverted by overhead trees or the broad layout of rain, irrigation is very focused on specific areas. This focus can equate to several gallons of water being sprayed on your fence every other day. While this is not optimal for a wood fence, most of the water will drain into the ground, run off or evaporate relatively quickly. 

But, if you have the fence line bordered with mulch it changes the whole dynamic. The mulch actually absorbs that water and slowly allows it to filter down into the soil.  It also prevents evaporation of the water within it and below it. That means that the mulch is holding all that water up against your brand new wood fence. And the mulch can hold that moisture and keep the ground below it wet for days. Then when you pile on the repeated irrigation there is just so much water there it is like your new wood fence is sitting in a pond. Some of that water is absorbed by the wood fence which expands the grains and over time makes it soft which leads to premature decay of the wood. This is true for treated pine and even more so for cedar, which are the two main wood options in the Southeastern US.

So, to help prevent the expedited decay of your new wood fence you either need to forgo the decorative mulch border or switch to something like pea gravel or river rock. This will allow the water to drain away faster and while leaving subsurface soil to remain moist for your plants. This simple change can help your fence live out it anticipated lifetime.