A pull behind helps make large spraying jobs a breeze and is the best tool to spray liquid fertilizers, weed killers, liquid insecticides, or water on large areas.
Of course, most tow-behind lawn sprayers can be easily mounted to any lawn tractor, ATV, UTV, or other vehicle.
In this article, we tackle the ins and outs of how to use pull behind lawn sprayer effectively and safely – pull behind attachments can be pretty inefficient (and may cause personal injury) if not used right.
How to use pull behind lawn sprayer
Let’s face it: Spraying insecticides, pesticides, and all kinds of water-soluble fertilizers around the yard with a pull behind sprayer can be incredibly tedious (to say the least) if you’re doing it for the first time.
In addition, the proper operation will ensure long, satisfactory service.
Here is how to use pull behind lawn sprayer to spray your yard or garden for grub control, crabgrass prevention, perennial weeds management, and more.
Before assembling or operating it, read the owner’s manual carefully to understand your specific unit’s basic operating and safety guidelines.
Proceed to assemble it by following the instructions outlined in the manual if you’re yet to do so.
General precautions to observe
- Chemical handling- If spraying chemicals, take note of the instructions and any caution notes relating to safe mixing and handling of chemicals.
- Speed- Always operate the equipment at reduced speed in rough terrain, hillsides, and ditches to prevent possible loss of control.
- Safe operation on steep slopes- Attaching a tow behind sprayer affects your tractor’s (or other vehicles) braking and stability. For this reason, it is advisable to steer clear of steep slopes- the attachment and/or towing vehicle could overturn.
Quick-Tip: To maintain stability when using pull-type spraying machines, consider adding additional weights to the towing vehicle (check the towing vehicle manufacturer’s recommendations).
- Know your vehicle- Know your towing vehicle’s controls and how you can stop safely. Refer to your towing vehicle’s owner’s manual for precise details.
Before starting the job, we suggest you test your sprayer with plain water- fill the tank with water and check for leaks (If a leak occurs, use thread tape to seal the fittings better).
This step has another benefit: you not only familiarize yourself with the machine before actual use, but it also prevents the wastage of expensive chemicals when on the job.
How to calibrate a pull behind sprayer
Proper calibration is one of the most important parts of spraying. Properly calibrated sprayers will save you both time and money.
As with any spraying equipment, calibrating your pull behind is vital- calibration ensures that only the proper amount of material is applied so you will maintain maximum accuracy no matter the job.
Follow the steps below to calibrate your sprayer to ensure accurate product application rates, perfect pressure, uniform spraying, and more before you start to spray.
By measuring off a 50 or 100 feet distance, you should manage to calibrate the speed of your towing vehicle by choosing a gear along with a throttle position that covers the stipulated distance in the listed time as below:
|Speed (mph)||Time required to travel (seconds)|
|50 feet||100 feet|
Determining the ideal amount of water to be used and speed
Now, chemical labels traditionally indicate the application rates (in gallons) per acre or gallons per sq. feet. Table 1 below shows an example of manufacturer-recommended application rates:
|2 mph||3 mph||4 mph||5 mph|
|2 mph||3 mph||4 mph||5 mph|
You can, therefore, use the following method to work out the ideal amount of water to be used and speed.
First, choose the amount of water to use based on your yard size:
The formula is Amount of water to use = Application Rate (check the chemical label) x Size of the target area
Example (assuming 4 acres yard size):
56.5 gal/acre X 4acres= 225.6 gallons @ 2mph
37.5 gal/ac re x 4acres= 149.6 gallons @ 3mph
28.0 gal/acre x 4acres= 112.0 gallons @ 4mph
22.5 gal/acre x 4acres= 90.00 gallons @ 5mph
Note: The example assumes the application rates listed in Table 1.
Next, select the speed/amount of water to use.
For a lawn tractor, 3mph is a comfortable speed.
So, choice = 149.6 @ 3mph (approximately 150 gal@3mph)
Then, figure out the number of tanks needed to complete the spraying job….
Here is how:
Amount of Water/Tank Capacity = Number of tanks (from the above step).
In short, if, for instance, your sprayer has a 25 gallons tank, the Amount of Water/Tank Capacity= 150 gallons/25= 6 tanks.
Now you have to determine the amount of chemical required.
Here you apply this formula: Amount of herbicide required= Rate (From Manufacturer’s Label) x Size of Area to Spray.
Assumption: We will assume that the Label reads 20 ounces/acre (check yours).
Hence in our case, we need 20 oz. X 4acres=80 oz.
Lastly, determine the amount of chemical to be added per tank.
Simply divide the Chemical Requirement by the Number of tanks as determined earlier.
So, we shall get 13.3 oz./tank (80oz./6.0 tanks)
This set of formulas is the simplest we have found to work for boom spraying.
Now add the proper amount of chemicals and water (to the tank).
Next, drive to the desired starting place and set the boom to spray.
Then, adjust the throttle to your previously determined position.
Proceed to flip the motor/pump switch “ON.” It now starts spraying.
There are two things you may need to do for the best results:
1. Adjusting pump pressure switch
The pump, in some models, features a pressure switch that senses the outlet pressure of the pump- the switch turn offs electrical power to the unit’s pump once it reaches a preset high-pressure point.
Note that with low flow demand, the pump could reach the predetermined high-pressure point making the switch initiate “cycling” (pump cycles off and on rapidly).
This should not worry you except if the pump is experiencing continuous cycling (rapid cycling within 1-second intervals for lengthy periods). However, you may need to adjust the pressure switch’s OFF setting value for optimum performance in some models.
Simply turn the set screw clockwise and counterclockwise (do not exceed one half turn either way) to increase and decrease the OFF setting.
It’s worth mentioning that, for the most part, the OFF and ON pressure setting is accurately configured at the factory, and adjustments may not be necessary.
2. Adjusting Operating Pressure
Tow behind sprayers are usually equipped with diverse valve types to control the operating pressure.
For example, some contain a bypass valve that you adjust while using to obtain your desired pressure depending on the spray product you’re applying.
Once adjusted- by slightly closing or opening it- this valve regulates the operating pressure generally by directing surplus pump flow back to the tank. If unsure, consult your owner’s manual for the correct steps to follow to set the optimal pressure if necessary.
Towable sprayers handle larger garden areas in a shorter time since they come with an extraordinarily large sprayer tank. Of course, you will drive it around (unlike walk-behind sprayers and backpack sprayers).
More importantly, you’re protected against coming into contact with poisonous chemicals since the implement is towed behind your back.
You now know how to use pull behind lawn sprayer accurately and proficiently, so your next job should be as easy as pie and look more professional.
References and Citations:
1.The University of Tennessee; Institute of Agriculture: Calibrating a Pull-behind, Two-nozzle-boom Turf Sprayer- https://extension.tennessee.edu/publications/Documents/W236.pdf
2. NORTHSTAR Proven Performance: Owner’s Manual Tow Behind Sprayers- https://www.northerntool.com/images/downloads/manuals/282785.pdf