The concept of weed block fabric sounds really smart at first. You roll out a fabric to cover your soil and prevent weeds forever right? The water passes through the pores, but the weeds can’t grow. I’m in!
You may be thinking after the first year. “Hey, this stuff really does work!” It’s often wishful thinking at best. Here’s what happens that can leave you with significant regrets.
Of course we mulch overtop of the fabric to hide it. So what happens to the mulch over time? It decomposes turning it into rich soil. After 2 or 3 years, your once effective and well-intended effort of putting down a weed barrier is now 2 or 3 inches deep into your soil layer. Now weeds can easily grow on top.
It’s important to remember that weeds are the ultimate “opportunist” plant. They grow where nothing else grows and in the poorest possible conditions. How ironic. Weeds only need a little tiny teaspoon of organic matter to germinate and start pushing out roots. The mulch layer you put on top of the fabric is plenty fine for many weeds to get going after just a few years of decomposition.
To make matters worse, the weeds growing on top push their roots down through the fabric pores making them very difficult to pull out. It’s like they are hopelessly trapped in the webbing. The weed’s roots expand and stretch the fabric leaving a hole. Over time your fabric is full of holes and has lost any integrity.
There is another annoyance to consider. Have you ever put down a weed barrier and then later realized that you’d like to plant some perennials or shrubs in that area? It’s a pain in the tush to pull back all the mulch, and then have to cut and trim the slimy fabric away so you can dig a hole. I’ve also seen many situations where someone planted a shrub in a tiny little cut-out and as the plant grew it was getting choked by the tight fabric.
One exception where I think weed block fabric makes sense is in a bed that you’re topping with rocks or river jacks. Some weeds will still grow over time once dust, debris and old leaves decompose, but it’s not usually problematic in a rock bed.
Save yourself the time, expense and disappointment of putting down a weed block in a garden bed. Put down weed preventing layer of compost or root mulch instead. Don’t be a block head.