How Far Back Can I Trim a Hedge?

The General Rule: Never More Than One-Third

The most important rule when trimming any hedge is the one-third rule: never remove more than one-third of the plant's total foliage volume in a single trimming session. This applies to virtually every hedge species found in Sydney gardens. Removing more than a third at once places the plant under significant stress, reduces its ability to photosynthesise and can trigger die-back — especially in older or established hedges.

If your hedge has been neglected and needs to be reduced significantly, do it gradually over two or three trimming sessions across different seasons rather than cutting it all back at once. This is the approach professional hedge trimmers like Jay Pro Lawn Mowing always use when restoring an overgrown hedge.

Why Cutting Too Far Back Is Dangerous

When you cut a hedge back into bare, leafless wood — sometimes called “brown wood” — you remove the plant's ability to produce new growth from that section. Unlike grass, most woody hedging plants cannot regenerate new shoots from dead wood. Cutting into bare wood can result in permanent gaps in your hedge that never fill back in.

The exceptions are some very vigorous species like certain Lilly Pilly varieties and Pittosporum, which can recover from harder cuts. But even with these species, cutting into bare wood is a risk — and the recovery is slow, often taking 12–18 months to fill back in properly.

Best Time to Cut a Hedge Back Hard in Sydney

If you need to make a significant reduction cut on your Sydney hedge, the best window is late winter to early spring (August–September). At this time of year, plants are emerging from their slow winter growth period and are about to push a flush of new growth — which means they recover from heavy cuts far faster than at other times of year.

Avoid making heavy cuts in summer (December–February) when plants are under heat stress and water demand is high. Autumn cuts are possible for some species but recovery is slower as the plant heads into cooler, slower-growth months.

Safe Trimming Depth by Hedge Species

Every hedge variety handles pruning differently. Here is a guide for the most common hedge species in Sydney:

Signs You've Trimmed Too Far Back

• Brown or yellow patches that don't green up within 4–6 weeks
• Bare sections of stem with no new bud growth after 8 weeks
• Wilting or shrivelling of remaining foliage immediately after cutting
• Visible dead wood that remains dry and brittle rather than pushing new shoots

If you notice any of these signs, stop trimming, water the plant deeply, apply a slow-release fertiliser formulated for shrubs and hedges, and give the plant at least 3–6 months to recover before any further cutting.

When to Call a Professional

If your hedge is severely overgrown, more than 3 metres tall, growing against a fence or boundary wall, or hasn't been maintained in several years — it's worth calling a professional. A professional hedge trimmer will assess the species, health and structure of your hedge before cutting, and use the right technique to reduce it safely over time without causing permanent damage.

Jay Pro Lawn Mowing provides professional hedge trimming across all Sydney suburbs. Call 0468 049 230 for a free quote and expert advice on your specific hedge.