Straight, even hedges are not the result of a steady hand — they are the result of a good setup before you start cutting. The most common mistake is trying to trim by eye without a guide line. The result is a hedge that looks straight from one angle, is clearly wavy from another, and then progresses to increasingly worse cuts over successive trims as you try to correct the previous session's errors. This guide covers the correct technique for getting a straight, even hedge consistently. For information on how often different Melbourne hedge species need trimming, see our guide on how often to trim hedges in Melbourne.
Tools you need before you start
- Sharp hedge trimmer — electric, cordless, or petrol. Dull blades tear rather than cut.
- Two bamboo stakes or garden canes — one for each end of the hedge section
- String line or a length of nylon cord
- Level or spirit level — to check the string line is horizontal
- Tape measure — for setting the target height consistently
Setting up a guide line: the most important step
The single biggest difference between a professional-looking hedge trim and a wavering amateur one is the use of a guide line. A taut string line set at the target height and run the full length of the hedge gives you a fixed reference point to work toward. Without it, your eyes compensate for small variations and the errors compound across the length.
How to set the string line
Push a garden stake into the ground at each end of the hedge section. Use a tape measure to set both stakes at exactly the same height above the current top of the hedge — the distance you want to remove. Tie the string line tightly between the two stakes, then check with a level that the line is horizontal. Adjust one stake until the line reads level. This is your cutting guide.
Top before sides: the correct order
Trim the top of the hedge first, using the string line as your reference. Move the trimmer along the top parallel to the string line, working in long smooth passes rather than short jabbing motions. After the top is done, set new guide lines for the sides — or use a vertical string guide if you want to ensure a perfectly plumb face.
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Getting the sides right: the batter angle
The sides of a hedge should not be perfectly vertical for best health results. A slight inward angle (wider at the base, slightly narrower at the top) is called a "batter" or "battering." This ensures the lower foliage receives adequate sunlight rather than being shaded by the wider top. A batter of around 5 to 10 degrees from vertical is ideal — barely perceptible to the eye, but it makes a significant difference to how evenly the hedge grows back.
Hedges trimmed with perfectly vertical or inward-leaning (wider at the top) sides tend to lose foliage on the lower sections over time as the upper portion shades them out.
Finishing and clean-up
After the main trimming is done, step back and view the hedge from a distance (at least 5 metres). Move around it. Small ridges and waves are much more visible from a distance than when you are standing close to the hedge. Touch up any obvious high spots with hand shears for fine work, or a quick pass with the trimmer held parallel to the face. For what to do with the clippings, see our guide on what to do with hedge trimmings in Melbourne.
FAQ: How to trim hedges straight
How do professionals get hedges so straight?
String lines, experience, and quality equipment — in that order. The string line is the most important element. Professionals use it on every job because trying to trim a straight line by eye alone over more than a metre or two is not reliable, regardless of skill level.
Why does my hedge look uneven after trimming?
The most common cause is trimming by eye without a guide line. The second most common cause is starting with an already-uneven hedge and trying to correct it without establishing a new level reference point. Set the string line first, commit to that level, and work consistently toward it.
Should I trim hedges when wet or dry?
Dry is better. Wet foliage sticks to the trimmer blade and creates drag, making the cut less clean. Wet clippings also clump and are harder to clean up. Trim when the foliage is dry, which in Melbourne spring and summer typically means mid-morning or afternoon after any morning dew has dried.
What is the best hedge trimmer for home use in Melbourne?
A cordless battery-powered hedge trimmer from a reputable brand (Makita, DeWalt, EGO) with a blade length of 450 to 550 mm is suitable for most residential hedges. For very large or very dense hedges, a petrol trimmer has more power but is heavier and noisier. The blade length matters for tall hedges — longer blades make it easier to maintain a consistent height when trimming above shoulder height.
