Anyone with a large garden will know how much of a full-time job it can be to effectively eliminate weeds and pests.
Hauling bottles and buckets of weed killer around with you is exhausting, and if your weed killer spills onto your plants, it may kill them too!
Using a manual pressure sprayer that can be slung over your back can be a real game-changer. The best knapsack sprayers will allow you to safely transport weed killer or fertiliser around whilst keeping your hands free.
If you’re thinking about buying a knapsack garden sprayer but aren’t sure what to look for, the following advice should help inform your decision.
Piston Pump vs Diaphragm Pump
When it comes to garden pressure sprayers, there are two types of ‘pump’ sprayer.
The two models can look relatively similar at first glance, but knowing the difference – and therefore knowing which one to choose – will make it easier to complete certain jobs.
In a piston pump pressure sprayer, there is a tube connected to the bottom of the main tank. Within this tube, a piston goes up and down to create pressure. Some piston sprayers are capable of delivering around 60 psi pressure. High pressure is useful for applying liquid fertilisers and spray herbicides because the droplet size will be smaller and therefore spread more evenly.
With diaphragm sprayers, the pressure is created by a component pushing up and down on a flexible diaphragm. The droplets created by a diaphragm pump system are generally bigger than those from a piston sprayer because the pressure is slightly lower. Therefore, these can be useful to stop liquid products from blowing in the wind, but there is a danger that they will deliver products in too dense of a concentration.
The fine spray from a piston sprayer will probably be more appropriate when applying liquid fertilisers etc. in a standard garden.
Material and Durability
It’s essential that your garden sprayer is made from a durable material that won’t corrode when exposed to harsh chemicals.
Most knapsack sprayers are made from sturdy, hard-wearing plastic, and you should ensure that the hose, lance, fittings and seals are all made of good quality materials too.
No matter the quality of your pressure sprayer, it won’t last as long if you don’t wash it out well between uses. If you’re using any chemicals, such as weed killers, make sure that none of the solution is left in the tank after use – it could corrode the plastic over time.
If you plan on using your knapsack sprayer for a few years, it’s good practise to check that you can easily replace broken parts. Ultimately, this will save you money in the long run.
Keeping the garden sprayer out of direct sunlight, and away from the elements. will also help extend its life. Plastic will degrade quicker when exposed to UV, so it’s best to store items out of the sun. Similarly, even if the plastic is frost resistant, it’s a good idea to store the pressure sprayer in a shed or garage over winter to avoid unnecessary damage.
Choosing the Right Capacity
The size of garden sprayer you need will depend on what you hope to use it for.
Generally, a 5 L tank will be best for small areas. So, smaller gardens, patios, and standard driveways. A 5 L tank will also mean a lighter unit when full, which might be more suitable if you aren’t able to support heavy weight for a long period of time.
Of course, with a smaller tank capacity you will have to fill it more often if you plan to do larger jobs.
For large driveways or gardens that need a lot of care and maintenance, a garden sprayer with a larger tank will save you time as they won’t need refilling as frequently. Keep in mind that a larger tank will add a considerable amount of weight to the unit when full.
A 12 L knapsack sprayer can weigh in the region of 15 kg when full of water (given that the unit itself also weighs something to begin with).
Choosing the right capacity ultimately comes down to how large the area you want to treat is, and how much weight you can comfortably support.
In terms of task-completion time, you may find it more effective (and safer!) to have a smaller garden sprayer that you can move around with more easily, rather than a larger one.
Adjustable Straps and a Comfortable Design
Following on from the subject of sprayer weight, you’ll find it far easier to carry a full knapsack sprayer if it’s comfortable.
Adjustable shoulder straps are crucial for comfort when it comes to comfort. For smaller garden sprayers, (1 – 7 L) one strap should be sufficient. One strap will keep your hands free whilst being enough to comfortably support smaller sprayer.
However, a backpack sprayer, with two straps, will be more comfortable for a sprayer with a larger tank capacity. Backpack sprayers, with two adjustable shoulder straps, stay in place and make it much easier to carry large amounts of liquid. Two adjustable shoulder straps will stop the sprayer from getting in the way, and will distribute the heavier weight much more evenly than one strap.
Also, look for a sprayer with a trigger lock. This will stop you from needing to hold the trigger down the whole time in order to achieve continuous spraying, and therefore help prevent aching hands and blisters.
Lance Length and Different Spray Patterns
Finally, take a look at the length of the lance and hose.
If the pressure sprayer has a hose that’s too short, you will be stooping continuously whilst working. This will cause pain and may also slow tasks down because you’ll have to constantly stop and stretch.
Make a note of the lance length from the product description and measure this against yourself. If you have to bend so that this measurement reaches from the floor to your hand, you may find that the lance of the manual pressure sprayer will not be long enough for you.
The spray lance should have an adjustable cone nozzle so that you can choose a different spray pattern depending on the job you’re doing. At the very least, you’ll want a jet option and a spray option.
Some pressure sprayers come with various detachable nozzles, so you can use different ones for a wide range of tasks. For example, a two-headed nozzle will allow you to quickly cover more ground.
Back To Contents