The purpose of pruning trees, shrubs and plants is to create the desired shape, maintain a certain size, remove dead or diseased portions and promote healthy new growth. With fruit trees, pruning is also used to increase flowering and fruit production, as well as to increase sunlight and air circulation through the canopy.
Most garden pruning tasks can be accomplished with simple hand pruning tools such as secateurs and loppers, which are used to make precise, clean cuts while minimising plant damage.
The Importance of Using Clean, Sharp Tools
Sharp tools cut more efficiently, making cleaner pruning cuts with less effort, while minimising damage to surrounding plant tissues, resulting in faster healing. By comparison, blunt tools crush branches or tear bark, and leave ragged pruning wounds that potentially provide an entry point for disease pathogens and decay organisms.
Since pruning cuts are being made into living plant tissue, the use of clean tools prevents diseases being transferred from tree to tree into fresh pruning wounds.
Good quality pruning tools can last a lifetime if they’re well maintained and cared for. Keeping tools clean prevents rust and corrosion. When regularly sharpened, they require less force to cut, and experience less wear and tear compared to dull ones. Additionally, replacement parts are available for many brands, significantly extending their serviceable life.
Types of Secateurs and Loppers
Secateurs are handheld pruning tools with two short blades, that are used for accurate and precise pruning of smaller branches, twigs, and stems up to 25mm thick.
By comparison, loppers are larger pruning tools with long handles that provide extra leverage to exert more cutting force, and are designed for cutting thicker branches and stems, while permitting reach of higher branches.
There are two main types of secateurs and loppers – those with bypass or anvil actions.
Bypass pruners are the most common, and have a curved blade that’s sharpened on one side only, which slides past a thicker lower jaw in a scissor-like action, providing a clean and precise cut.
Anvil pruners have a straight blade that’s sharpened on both sides, which cuts against a broad, flat lower jaw. They can make larger cuts more easily than bypass pruners, and are suitable for cutting thicker, harder or dead branches, but tend to damage the branches more.
Heres’ a few handy pruning tips:
- For more precise pruning when using bypass secateurs, cut using the tip.
- The back of the jaws of secateurs and loppers provides the most cutting force for heavy cuts.
In the following section, we’ll show you step by step how to clean and sharpen your pruners.
Cleaning Sap from Pruning Tools
The most effective way to clean the blades of pruning tools and prevent the spread of diseases is to spray them with a 70% alcohol solution (3/4 methylated spirits mixed with 1/4 water) immediately after pruning each tree. Wipe with a paper towel or cloth to clean off any adhering sap. For proper sterilisation, spray the blades again with alcohol solution and allow it to slowly evaporate.
Hardened plant and tree sap may be removed using a plastic kitchen scrubbing brush with dishwashing liquid and warm water.
More persistent sap can be removed by wiping with a paper towel or piece of cloth with a few drops of vegetable oil. The thinner grades of vegetable oil can also be used to wipe down pruning tool blades after cleaning to stop them rusting.
If these methods mentioned don’t work, then remove hardened sap using use mineral turpentine, or a penetrating oil such as WD-40. They’re messy, so wear disposable gloves, and toxic to plants, so wash them off the blade afterwards with soap and water!
Removing Rust
Corrosion and rust can be removed with a Scotch-Brite synthetic abrasive pad, which can be purchased from a paint store. Use the grey-coloured ones, they’re an ultra-fine grade that won’t leave marks on metal. The green ones are found in kitchens, and are used for everyday cleaning of most cooking utensils and equipment, but they’re a coarse grade, and leave lots of scratches on polished surfaces.
Always scrub in one direction only, toward the blade edge to avoid blunting it and also cutting your fingers!
It’s important to also scrub the lower jaw clean and remove any dirt stuck in the sap groove.
Rusty blades can also be cleaned with a wire brush. Brass wire brushes are gentler than steel ones and won’t scratch steel surfaces.
Sharpening
With bypass secateurs and loppers, only the bevelled (angled) side of the blade is sharpened, do not sharpen the flat inside of the blade that shears past the lower jaw, as that will ruin the cutting action!
Pruning tools can be sharpened quickly and effectively by using a diamond sharpener. A fine grit sharpener is ideal, as a medium or coarse grit removes too much steel.
Step 1: To sharpen secateurs, hold them firmly against a tabletop with the blade facing away from you.
For a firmer grip, hold the handle down with the blade extending past the edge of the tabletop.
Step 2: To begin sharpening, rest the tip of the diamond sharpener on the inside edge of the blade.
Ensure that the diamond sharpener is angled so it sits flat on the thin shiny silver bevel of the cutting edge (the micro-bevel), which is approximately at a 23-degree angle. Do not rest it on the larger main bevel!
Step 3: Using moderate pressure, while keeping the diamond sharpener flat on the fine edge bevel, push the diamond sharpener forward and across in a single stroke at the same time.
Step 4: Continue pushing the diamond sharpener forward and across along the edge bevel in one continuous motion.
Step 5: Finish the sharpening motion at the tip of the blade with the diamond sharpener pushed all the way forward. Repeat this stroke around 10 times for a relatively sharp blade, and 20-30 times for a fairly blunt one.
An alternative sharpening method which may be easier for some is to hold the diamond sharpener against the edge bevel with moderate pressure, and make small overlapping circular movements while moving along the blade towards the tip.
Step 6: The sharpening process creates a small burr, which is a microscopic curl in the edge of the blade that needs to be flattened. You can lay your finger on the flat side of the blade (not the sharp edge) where you will feel a slight protrusion. This burr can be used as an indicator to show you where the blade has been sharpened. Lay the diamond sharpener flat against the back of the blade, and push it upwards three times to remove the burr.
The diamond sharpener should move in a straight line towards the tip for burr removal, and polish the whole inside of the blade that it’s resting against.
Push the diamond sharpener flat along the inside of the blade all the way to the tip to remove the burr along the whole length of the blade. That finishes the sharpening process.
Step 7: To test whether the blade is sharp enough for making clean cuts, use the ‘fingernail test’ – gently and very carefully press the blade on the fingernail, if it catches, it’s plenty sharp, if it slips, resharpen it. Test different sections of the blade, as some parts may be sharper or duller than others. Resharpen the duller section, then the whole blade once again to obtain even sharpness along the length of the blade. For a safer alternative test, just try cutting thin slivers from a piece of thin cardboard such as from a breakfast cereal box or something similar, or cut some thin branches to determine how clean and easy the cuts are to make.
Note that fine tipped floral snips have symmetrical blades that both have bevels that need to be sharpened.
There are other types of sharpeners that gardeners may encounter in retail stores. A sharpener with a very shiny polished rectangular metal blade is a carbide sharpener, it will tear shavings off a metal blade and remove way too much steel for regular sharpening, but may be suitable for renovating badly damaged or worn blades.
A second type of sharpener may look like a white ceramic stone, and these are ceramic sharpeners that are used to quickly to touch up a sharp blade to razor sharpness, but they don’t really remove any metal to sharpen a dull blade.
Renovating Old Tools
Step 1: Really old blunt pruners, especially ones that have chips or ‘teeth’ (notches) in the blades need a lot of metal removed to create a smooth, even edge that is suitable for sharpening. A fine mill file is suitable for the task, just remember to maintain the angle of the fine bevel.
Step 2: After file sharpening, refine the edge with a carbide or diamond sharpener.
Adjusting Blade Tightness
All pruners and loppers have a main pivot nut and bolt that keeps the blades together, and can be tightened for better cutting.
To adjust the tightness of the blades:
Step 1: Open the tool up, with the blades pointed away from you.
Step 2: Remove the spring by pushing it inwards from one side. Wear gloves as the spring may be greasy!
Step 3: With secateurs, test them by holding them level, opening the blades and then slowly letting them close under their own weight. The blades should cross between 1/2 & 2/3 of the way along their length towards the tip when they stop.
Step 4: If the blades close too much that the tips meet, tighten the main nut a little and then retest. Conversely, if the crossing point of the blades is before the half-way point, then loosen the main nut and retry. On some secateurs it may be necessary to loosen the small toothed fan-shaped locking segment first that locks the nut in place.
In summary, regular maintenance of pruning tools, including cleaning and sharpening, is a good practice for anyone involved in plant care.