Category Archives: Lawn Management

Chemical Trimming

Chemical trimming

Spin trimming is a hassle. It is almost never fun, no matter how much or how little there is to be done. Obviously, the less there is to do, the better, but any is enough to leave you feeling irritated. There are some ways to make trimming a less frequent, or even an almost never needed operation.

If you live in suburbia, you can benefit from this method, and if you live in a rural area with lots of fence rows, this type pf trimming can save you a ton of money, time and aggravation.

Chemicals used for chemical trimming

There are two types of chemicals that can be used for chemical trimming: Growth regulators, and herbicides. Some herbicides can be used for regulating growth if used properly as well.

Chemical trimming with growth regulators

With preventive growth regulators, you trim the grass around your home and property by slowing it’s rate of growth. Some growth regulators offer a 50% decrease in growth for a month or more. The advantage to using these is that you will cut your trimming in half, and still leave your grass green and growing, although it will be growing slowly. The downside of this method is the cost of preventive growth regulators. They can be expensive, but compared to the cost in time, labor, and fuel of trimming weekly, you will still come out spending less.

Chemical trimming with herbicides

The use of an herbicide to trim chemically, implies killing the grass. This is usually not desirable in a fine lawn, but if you have a mile of curb line or fence row to trim, a well done 6 inch straight line of dead grass beats an overgrown fence row, or a poorly trimmed fence row any day. The advantage is that there will be no trimming needed if it is done early and kept up with occasional spot treatments. The disadvantage is that it kills the grass. That is not necessarily a bad thing, but it is not as attractive as a carefully trimmed line, and it should be done carefully and thoughtfully where erosion might be a problem.

Chemical trimming using herbicides as growth regulators

It is possible to regulate growth with some standard herbicides. This is usually a very diluted mixture which stunts the grass and slows the growth. The one I prefer is glyphosate. This comes under several brand names most notably “RoundUp Pro” There are directions on the label for this type of application, and it will need to be very carefully measured, calculated, and calibrated to get the best result.

No matter what type of chemical you use, whether for killing the grass, or regulating the growth of the grass, you will need to make some careful calibrations.

First, you should read the label of any chemical you use, and follow the directions as though your life depends on it. There are two very good reasons for this.

  1. The directions on the label are there for a reason, and they will not lead you wrong. Using more of the product than called for will not give better results, and in many cases, will produce the opposite result.
  2. The label is the law. “It is a violation of federal law to use this product in a manner inconsistent with it’s labeling.” is a phrase that is oft repeated by chemical professionals who have learned the truth by experience.

Calibrating the sprayer for chemical trimming

The best way to properly calibrate a backpack sprayer for someone who is not already familiar with the process is this: You should determine the distance you need to travel, and then time yourself walking a portion of it with the backpack sprayer full of water spraying a mock application. You should use the nozzle that you will be using for the application. This will help you to determine both the time it takes to travel the course, and the amount of water used for the distance.

If the test was 100 feet, and the entire distance 1000 feet, and 1 quart of water was used in 2 minutes of travel time spraying a line 6 inches wide, then you have sprayed 50 square feet in 2 minutes. You can reasonably expect to spray 100 square feet, or 200 feet, that is 100 square feet in 4 minutes, which would give you a total of 500 square feet or 1000 linear feet of 6 inch line in 20 minutes using 10 quarts, or 2.5 gallons of water for the entire distance.

If the label calls for using 4 ounces of product per 1000 square feet, and you are only going to cover 500 square feet, then you would, of course, use 2 ounces in 2.5 gallons of water to spray the entire distance.


If adding surfactant is suggested, be sure to add the recommended amount. If spraying for growth suppression, do not over use the surfactant, because it will increase the herbicides effect.


If any suggestion on this site is contrary to the suggestions, or restrictions, or any other part of the product label, the product label should be given precedence. Please check all facts and calculations before making an application.

See also: Mowing Options Chemical Mowing