The Nuts And Bolts Of Sprayers

Imagine you’ve discovered bugs in your garden that you need to get rid of. You go to where you keep your garden tools and you pick up your battery-operated spray gun. A short walk to where the bugs were spotted, you aim, and your electrostatic spray gun discharges an organic insecticide whose particles are electrostatically charged. The charged particles race from the gun, and because their charge is the opposite of the charge of the plant foliage, there is an instant attraction. The spray hits the plant, sticks to the foliage and nothing else. Within minutes the bugs are dead, the insecticide becomes inert and the job is done.Not really a fantasy. Electrostatic spraying equipment that performs just the way I described is available and used in the greenhouse industry—but not for us home gardeners. For us there are the traditional sprayers that our parents and grandparents used. For the home garden and estate these are basically piston, diaphragm, hydraulic and roller-type sprayers that can be gas or electrically powered. The most common sprayer, though, is the compression sprayer where you add your spray to a tank, pump a plunger, pull a trigger and the spray comes out the nozzle end. There’s a lot to know about these simple sprayers that will keep them working, keep you safe and take care of your weeds, insects and some (only some) of your plant diseases.

The original compression sprayers were all metal, and they were heavy. The present-day sprayers are mostly plastic and light, but there is a great range in prices and quality, and the cheap ones can be nothing but trouble. They come with hoses that are attached with crimped metal clamps, triggers that jam and nozzles that allow sprays to come out in useless patterns. One that I purchased recently leaked air where the spray hose came out of the tank, and there was no way to fix it. After several uses the trigger would allow liquid to flow only intermittently and the nozzle would dribble as much as it would spray. It cost $22 and was not made by one of the reputable manufacturers like Solo, Hudson or Chapin.

So what should you look for when buying a compression sprayer and how much should you expect to pay? Let’s start with the basics. These sprayers come with tanks that start at 1 quart capacity and go all the way up to 4 and 5 gallons. A 1-quart is pretty useless unless you have a tiny garden. The next size is a ½-gallon, and that could be just right for patio work or a small vegetable garden or yard. A 1-gallon sprayer is probably ideal for many of us, but here you need to keep in mind that water weighs 8 pounds per gallon. Add the weight of the sprayer and you’re already carrying around 10 pounds, and with a 2-gallon sprayer nearly 20 pounds. The good news is that you can buy some of these sprayers as wheeled units so you don’t have to lift them.

Also consider what you’ll be spraying. It’s never a good idea to use the same sprayer for herbicides (weed killers) and insecticides. All it takes is one mistake when you leave a little bit of herbicide in the sprayer and forget to rinse it. The next time you add your insecticide for the flowers or vegetables and days later you’re noticing that the bugs are dead, but so are the plants. If you can afford to, it’s a great idea to keep two sprayers to avoid this problem and with a marking pen put a big “I” on one for the insecticide and a big “H” on the other for herbicide.

If you take a close look at most of these sprayer tanks you’ll notice that the gauge markings for the amount of liquid in the tank are usually translucent and hard to read. Use your marking pen to highlight these markings or even note the ½- and 1-gallon marks in writing. This will eliminate a lot of guesswork and will keep your mixing much more accurate.

In the tank you’ll see or insert a feed tube that will connect to the neck of an opening on the side of the tank. The spray hose connects to the feed tube and the hose should attach to the tank with a screw-type fastener and not be pre-clamped. The spray hose then gets attached to the feed end of the trigger, and again this connection should be a screw-on type and not a clamp. The trigger will usually be plastic, but the best sprayers have metal or brass triggers that last much longer and are infinitely more reliable (and more expensive). A plastic or metal wand gets attached to the other end of the trigger—with a screw, not a clamp connection. At the end of the wand there is a nozzle.

The nozzle is a pretty tricky character and it needs to be the right one and well cared for. Most sprayers come with a nozzle that loosens and tightens on the wand. Twist the nozzle in one direction (tighten) and you get a fine spray pattern in the shape of an inverted cone. As you untighten the nozzle the pattern compresses to a stream. What most gardeners don’t realize is that some of the higher-end compression sprayers like some of the Chapins and Solos can be adapted with several spray tips that are color-coded for their spray pattern and output. This gives you the option of a fan pattern, cone pattern or stream with the output measured in gallons per minute (even though you’ll actually be spraying much less than any gallons per minute). A good garden center or farm supply store should be able to help you find both a good sprayer and one that will take different spray tips.

Maintenance of the sprayer is critical. It needs to be washed and flushed after every use, making sure that the tank is kept clean and the nozzle free of any debris. It’s very easy to get tiny pieces of garden “stuff” into the tank and this will eventually foul the trigger or get stuck in the nozzle or orifices that feed the nozzle. With fresh water in the tank, build up some pressure, remove the nozzle tip and let the fresh water run through and flush the nozzle with and without the tip on it.

The one part I’ve left out is the all-important plunger. This is the gizmo with the handle on it that you pump up and down to pressurize the tank. The instructions that come with the sprayer will tell you how many pumps are necessary to pressurize a full tank—and keep in mind that a half tank will need more pumps. You’ll also need to pump from time to time as you’re working to maintain the same pressure and volume. Never over-pressurize your tank, as this affects the volume and spray pattern at the nozzle and you really want that to be consistent. Also critical is that you should try to buy a sprayer with a pressure relief valve. This is a small valve on the side of the tank that allows you to release the pressure when you’ve finished spraying. Otherwise you need to unscrew the plunger to release the pressure, and this can result in spray mist shooting up at your face if you’re not very careful. The relief valve eliminates this danger … but only if you use it.

Expect to spend no less than $30 for a simple sprayer, but you should be ready to spend up to $50 and more (Solo model 454V is great). Make sure spare parts are available where you buy it. Always follow the instructions that come with the pesticide. Don’t ever think that more than the recommended amount per gallon is better. Never spray insecticides or herbicides when it’s very hot and sunny (like over 85 degrees, though I’d stop at 80) or windy, as this can cause unintended injury to the plants and spray drift.

Got sprayer questions? Send me an email. Follow the directions, keep us all safe and keep growing.