Pre-emergent Herbicides

Weed control is a pain.  There is no magic bullet that will eliminate all weeds from your yard.  There are, however, different tips and tricks that will make weeding much, much easier – and less expensive.  One of those tricks is to regularly use a pre-emergent herbicide.


People are more familiar with post emergent herbicides like Glyphosate (Roundup), and 2, 4-D (Weed-B-Gon.)   These products work by killing existing weeds in a yard.  Pre-emergent herbicides work on a completely different principle and stop the weeds from growing in the first place.  Think along the lines of “an ounce of prevention is worth a pound of cure”Pre-emergents stop the weeds before they grow.


The pre-emergent herbicide creates a temporary barrier in the top layer of the soil that stops weed seeds from germinating.  This is perfect for stopping annual weeds, and it prevents perennial weeds from spreading by seed to other areas of a yard.  It does not treat or kill anything already growing or alive.  This makes per-emergents safe to use in lawns and near trees and plants.


Established weeds, and perennial weeds that spread without seeds are unaffected by pre-emergents.  These are treated with more traditional post emergent herbicides instead.


Timing is important with pre-emergents.  The weed growth barrier only lasts for 2-3 months.  If applied correctly, this barrier can block the majority of new weed seeds in critical times.  An application in the fall and the spring is typical.  Applying the per-emergent herbicides at the wrong time of year will have no impact on the weeds in the yard. 


Repeated applications over the years are also recommended.  Many seeds, like the common burr clover, can stay viable for over three years hidden in the soil.  Skipping an application can give weeds an opportunity to return with a vengeance, even if no sign of the weed has been seen in years.  This is even more vital at properties that border wild or unmaintained areas. 

Even with its limitations, pre-emergent herbicides are a powerful tool in weed prevention.  Proper application at the right time can keep your yard looking healthy and weed free.

Posted in ,