What To Prune And When

Pruning is not complicated once you understand the three basic principles. These guidelines hold true whether you’re pruning trees or shrubs. Here are three top tips to pruning.

Choose the Right Tool

Always use clean, sharp tools. Select the right-size tool for the branch you will prune to avoid damage to the plant and the tool. Use a pruning saw on branches larger than 4 – 6cm in diameter. Pruners work best on the smallest branches. Use loppers on branches an inch or so in diameter. 

Choose the Right Time

There isn’t a single best time for pruning. Late winter is an ideal time for pruning many trees and shrubs because they are dormant and it is easier to see what needs to be pruned. Late-winter pruning promotes fast regrowth in spring. Some trees, such as maples, birches, and magnolias, bleed sap heavily if pruned in late winter. This causes little harm but can be avoided by pruning these trees after they are fully leafed out in late spring or early summer. Summer is the best time to remove dead branches when they stand out.

Prune spring-flowering trees and shrubs right after they finish flowering in spring. Trees and shrubs that bloom during summer and into fall are best pruned in later winter or early spring as soon as their annual growth begins. Refrain from fall pruning because it stimulates new growth that could be killed by winter cold. Prune anytime: suckers; water sprouts; branches that are dead, diseased, or damaged.

Make the Right Cuts

Holding the thinner, upper cutting blade nearer to the trunk or main stem, make a clean cut without tearing the bark. Avoid leaving a stub, which is unsightly and provides an entry point for pests and diseases. Cut just outside the branch collar, the swelling where the branch begins.


Be safe when pruning

  • Dress appropriately for pruning, wearing long pants, long-sleeved shirt, gloves, safety glasses, and non slip shoes.
  • A wide brimmed hat keeps you protected from the the sun, but make sure it doesn’t obsure your vision.
  •  Keep tools sharp and clean. Store a sharp tool in a protective cover, if possible.
  • Carry pruning tools with the points facing down.
  • Choose a clear, still, dry day for pruning.
  • If you must prune from a ladder, tie it securely to the tree. Keep one hand on the ladder and one hand on your pruning saw. Also try and arrange for  someone on the ground to help secure the ladder further.

Tools for pruning

The most important pruning tool is a good quality pair of secateurs. These should be the best you can afford. It’s a handy tip to wrap some brightly-coloured plastic tape around the handle. This makes the secateurs stand out clearly, even if they are left half-buried in mulch on the side of a garden bed. Keep blades sharpened and joints oiled. Basic maintenance will help your tool last longer.

A good saw is another requisite. Ideally, select one with a narrow blade that can be manoeuvred into crowded parts of the plant.

Hedge clippers are necessary for trimming formal hedges. If this sounds like too much hard work, invest in a pair of electric or batter-powered shears.

And don’t forget a strong pair of gloves – especially for rose pruning! (pictured)

How do roots do their work?

Some plants have a long, strong taproot with smaller lateral roots.  Others have a branched fibrous root system. 

Whatever form it takes, the root system absorbs water and dissolved nutrients from the soil through the root hairs (elongated cells just behind the root tip) and passes them to conducting tissue in the root, then on to the stem and other parts of the plant. 

Roots must respire (or breathe) to perform their task of absorbing and conducting efficiently, so a soil must be able to provide oxygen as well as water and nutrients.

Here are some common reasons for pruning:

  •  To preserve the shape of the plant
  • To restrict the size of the plant (much better, though, to choose a plant that will grow to fit the space rather than being forced to constantly prune).
  • To encourage productive growth (e.g. flowering shoots on roses and fruiting wood in the orchard).
  • To remove dead wood
  • To remove old canes from the base (as in plants like May bushes and abelia).
  • To thin a canopy and allow air movement through branches.
  • To form plants into special shapes – topiarising, standardising or espalier.
  • To encourage colourful new growth (e.g. new red leaves on photinia).
  • To maintain a hedge or screen
  • To ‘stop’ upward growth on plants and encourage branching.
  • To reduce competition by thinning out crowded growth
  • To remove suckers from root stocks on grafted plants. 

What to prune in winter

Prune most deciduous fruit trees, roses, grape vines and ornamentals. Delay pruning of spring flowering varieties until flowering’s finished, otherwise you’ll cut off the incipient blooms.

Related products

Yates Garden Guide - 79th Edition

New Zealand's bestselling and most trusted gardening guide revised and updated, the 79th edition is a must-have for keen beginners and green thumbs alike.

More project guides & articles