Impermeable Weed Mats


Staff member
I ordered the wrong weed mats for my sawtooth oaks. I thought I was ordering permeable material like lumite, but I actually ordered an impermeable plastic material (think heavy duty garbage bag).

They are 3x3' squares...will they help by trapping moisture that somehow gets underneath the mat (by moving horizontally through the soil?) or will they hurt by preventing water from reaching the soil?

They feel so cheap and chintzy that I don't see them lasting long anyway, but will they help in the short term?
I got some of those once and took a pitchfork and punched a bunch of little holes in them. Only had them a couple of years so not sure how they will last. Don't really want any more. They might be okay at a place where the soil moisture was very good the whole year and you weren't worried about blocking out the rain water.

I used some of those last weekend in a spot I don't worry about soil moisture and this time didn't do any hole punching.
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You will not get moisture from above but what you will find is that your moisture evaporation will be eliminated. If your soil has moisture in it now the black plastic will retain it. I do this in my garden every year using visqueen as a weed barrier and have been amazed at how long into the summer I can go without watering. I do however have a drip irrigation system for later in the summer. I get 2 years out of my v is queen before it needs to be replaced. So I'd say in your case it will work for the short term, but late summer you will have issues unless you have a way to irrigate.
I can water the trees as needed throughout the summer so that won't be a problem. I just didn't want to put the impermeable material down if it would hurt the seedlings.
If your trees are anaerobic tolerant then impermeable material won't hurt them, but it they are anaerobic intolerant they could be starved for oxygen. What kind of trees are you planting?