Solo 425 Backpack Sprayer Review

The Solo 425 is a backpack sprayer used for gardening and horticultural purposes. It’s used to distribute water or other substances evenly over a large area of grass, flowers, leaves, or any other type of foliage you want to treat.

The Solo company got its start in 1948 when brothers Hans and Heinz Emmerich designed one of the first truly portable two-stroke engines. Weighing in at under 15 pounds, it was far smaller and lighter than most other two-stroke engines at the time, meaning it could potentially be used to power a variety of handheld devices.

In 1951, the brothers put this idea into practice and developed a portable mist sprayer powered by one of their small engines.

Previously, the only spray devices available were powered by large, stationary engines and required tons of hoses and manpower to operate, but the invention of a backpack-sized mist sprayer meant that spraying lawns could now be a completely solo effort. The “solo” operation of their products is the basis for their brand name.

Today, Solo manufactures a variety of sprayers, sprayer accessories, and other gardening equipment.


  • The plastic tank is resistant to UV light and corrosive liquids, so it’s durable and won’t crack
  • This sprayer features an “extra-wide” tank opening to make filling the sprayer easy
  • This sprayer is capable of up to 90 psi of pressure
  • The sprayer is backed by a 1-year warranty


  • The piston pump isn’t great for non-liquid spray agents
  • Some reviewers report that the shoulder straps tend to slip off easily

Things to Consider Before Buying a Backpack Sprayer

Before buying the Solo 425 or any other backpack sprayer, you should first consider what sorts of features it offers as well as whether or not a backpack sprayer is suitable for your needs.

A backpack sprayer is a great tool for quickly dispersing pesticides and fertilizers over a large area of lawn, but if you don’t have a particularly large lawn or a large amount of foliage to treat, then a backpack sprayer can be a bit of overkill.

Many backpack sprayers are specifically designed to be able to cover a large area and may actually be more difficult to use on smaller areas.

Setting up a backpack sprayer properly can be a bit complicated; you have to correctly calculate the amount of water needed for the area as well as the amount of fertilizer/pesticide you want to apply.

You can’t just dump whatever amount of spray agent you want in the tank and expect it to work; many spray agents, in particular weed killers, don’t actually work if you overdose your lawn with them.

You also have to take into account factors like your walking speed, the type of spray nozzle you’re using, and the width of your spray. In truth, using a backpack sprayer is a lot of work! If you’re not all that serious about lawn care or you don’t have a large area that needs to be treated, then using a backpack sprayer may be more effort than it’s worth.

But if you know you’re in the market for a backpack sprayer, here’s what you should consider before choosing one.

Electric versus Manual Pumps

All backpack sprayers come with a pump used to pressurize the liquid in the reservoir and send it out the nozzle. However, some backpack sprayers use battery-operated pumps while others feature simple hand pumps.

The advantage of electric pumps is that they’re far easier to use than manual pumps since you yourself don’t have to physically do any pumping to pressurize the spray. Electric pumps are better if you want to cover a particularly large area. However, electric pumps need to be changed frequently, and they tend to break down more easily than manual pumps.

Manual pumps require more physical effort to use but don’t need to be charged, don’t require as much maintenance, and are usually a lot less expensive than electric pumps.

Sprayer Tank Capacity

It’s not always the best idea to just grab the sprayer with the largest tank available. If you need a sprayer tank with a large capacity, then so be it, but a larger spray tank obviously means a bulkier and potentially less comfortable spray gun. On the other hand, if your tank is too small, then you’ll be forced to stop frequently to refill.

Finding out in advance what tank size is suitable for your needs will make every spraying a lot easier to finish.

Type of Pump

Most backpack sprayers use either a piston or a diaphragm pump. Piston pumps are cheaper than diaphragm pumps but are harder to maintain and less durable, especially if you’re frequently using dry formulations in your sprayer.

Features & Benefits of the Solo 425

The Solo 425 is the entry-level sprayer manufactured by Solo. As such, it’s pretty basic in terms of the features it offers, although it’s still completely capable of doing pretty much anything that you might need to do with a backpack sprayer.

Let’s get right into the features of the Solo 425 and the benefits that each feature provides.


The Solo 425 features a 4-gallon (15-litre) tank, which seems to be the industry standard in comparison to most other backpack sprayers. The tank is made from durable plastic and is intended to be resistant to ultraviolet light and corrosion, meaning you can use it for many hours in direct sunlight without having to worry about the tank cracking and becoming unusable.

The tank is also contoured in order to fit the curvature of your back more comfortably and comes with a wide opening for liquids with a strainer built in to ensure that no unwanted solids get mixed in with your spray liquids,

Spray Wand and Hose

It comes with a 28-inch long spray wand, which connects to a 48-inch nylon-reinforced hose. The reinforced hose is a necessity, as the piston pump in the Solo 425 is capable of generating up to 90 psi of water pressure. Compared to other backpack sprayers, 90 psi seems to be a bit above average in terms of the pressure that most of these sprayers are capable of.

With the long wand and hose, you should have no trouble spraying into tight spaces or up high into the branches of trees.

Piston Pump

While the piston pump does offer a lot of power, it also, unfortunately, makes the Solo 425 less capable of handling powder- or granule-based spray agents. As such, it can only really handle liquids. Nonetheless, it’s still capable of distributing a variety of spray agents, including disinfectants, herbicides, pesticides, and fertilizers.

You can mount the pump handle on either side of the tank, so you can use it with your left or right hand, whichever is easier. The pump handle also comes with a built-in holder for the spray wand, so you can easily secure the wand when you’re not actively using it.

Spray Nozzles

The Solo 425 comes packaged with four different spray nozzles for spraying in different configurations. You get a standard adjustable spray nozzle, a fan spray nozzle, a hollow cone spray nozzle, and a jet spray nozzle. The spray wand is also compatible with TeeJet products, so you have the option of purchasing additional, even more, specialized nozzles.

Shut-Off Valve

The Solo 425 features a shut-off valve integrated into the spray wand that can be locked in either the open or shut position. The valve makes the sprayer really convenient to use if you want to spray a very large area since you can lock the valve open and have it continuously spray without you having to hold down the trigger constantly. Also, being able to lock the valve open means less strain on your hands from squeezing the trigger on and off all the time.

Being able to lock the valve closed is also handy since this can help prevent you from wasting any spray solution if you accidentally hit the trigger on the spray gun.

Metal Frame

The tank, spray wand, shoulder straps, and pump lever are all attached together via a strong metal frame. The metal frame also doubles as a base for the whole sprayer assembly, which makes it easy to set the sprayer down and fill it up without having to worry about spillage.

Viton Seals

The Solo 425 was designed so that no metal or rubber can come into contact with potentially corrosive liquids. To that end, this sprayer is built with Viton seals in key locations.

Viton is a brand of FKM, which is a type of synthetic rubber made from fluorocarbons. FMS are more expensive than other types of synthetic rubber-like neoprene or nitrile rubber, but the upside is that FKMs are more resistant to heat and chemicals than other synthetic rubbers are.

Social Proof

The best way to see how this product actually performs in the real world, however, is to look for testimonials from actual product users. Here, we’ve compiled some reviews from Amazon that we felt best summarized the overall customer experience of using the Solo 425.


Even in the more negative reviews, the most common complaint is that the shoulder straps aren’t all that great, which certainly isn’t ideal but probably won’t be a huge dealbreaker for most people.

Alternative Products

If you’re looking for an alternative backpack sprayer to the Solo 425, you still have plenty of choices. Here are three other backpack sprayers we’d recommend:

Husqvarna 4-Gallon

This 4-gallon backpack sprayer from Husqvarna is an excellent alternative to the Solo 425. The Husqvarna sprayer is slightly more expensive than the Solo but offers greater functionality.

For one, its pump is capable of producing up to 150 psi of pressure, making it about 60% more powerful than the Solo 425. Its pump is also capable of handling non-liquid spray agents, making it a more versatile device than the Solo 425.

You can check out the current price of the Husqvarna sprayer on Amazon.

Roundup Backpack Sprayer

If you’re looking for a slightly more budget-friendly option, then this backpack sprayer from Roundup is a solid choice. It offers most of what the Solo 425 offers, but for a lower price.

Aside from the price, the only real difference between the Roundup and the Solo 425 is that the Roundup seems to only come with three different nozzles instead of four. The Roundup sprayer is also compatible with TeeJet products, though, so you can easily buy more nozzles for the Roundup if you need any.

You can find all the info about the Roundup backpack sprayer on the Amazon store page.

Solo 475

The Solo 475 is extremely similar to the Solo 425, but these two products differ in a couple of key ways.

For one, the Solo 475 has a diaphragm pump as opposed to a piston pump. This means that the Solo 475 is capable of handling both liquid and non-liquid spray agents.

The Solo 475 is also only capable of 60 psi, while the Solo 425 can achieve 90 psi. Still, if you’re looking for a backpack sprayer that can accept more types of spray agents, the Solo 475 is the one to go for.

If you want to check out the Solo 475 further, you can do so right here on Amazon.


The Solo 425 is a solid entry-level backpack sprayer. If you’re reasonably serious about your gardening habit but aren’t trying to spend a ton of money on a fancy battery-powered sprayer, then the Solo 425 is a pretty decent choice all-around.

And if the Solo 425 isn’t up to your standards, there are plenty of other backpack sprayers available that improve upon the various features of the Solo.

But if the Solo 425 sounds like a product that interests you, you can buy it or find out more about it on Amazon. Best of luck with your lawn care!