Shaping up

Q. What are the main benefits of pruning hedges?

Pruning promotes dense growth, maintains shape, and improves airflow and light penetration – creating long-lasting, attractive and functional screening.

Q. How old should the plant be when I start pruning?

Popular hedging plants such as common box (Buxus sempervirens), coastal rosemary (Westringia fruticosa) and others should be pruned in the first year – after they’ve established and are putting on new growth. Regular tip-pruning (2–5cm) encourages side shoots and helps fill out the hedge. In the second and third years, start shaping the sides to the desired line, keeping the base slightly wider than the top so light reaches the bottom. Let the plants grow close to your desired height before removing the central leader, which is then pruned lightly to trigger side growth and create a flat, dense top.

Q. How often should I prune my hedge to keep its shape without causing stress?

This depends on the plant species you’re using and the look you’re trying to achieve. As a guide, when growing a relatively small, neat hedge (correa, escallonia or Photinia ‘Red Robin’, for example), prune roughly every 4–6 weeks through the growing season and every 6–8 weeks in the cooler months. For larger trees such as weeping lilly pilly (Syzygium floribundum), sweet viburnum and Ficus hillii ‘Flash’, once a year could be sufficient.

Q. What’s the difference between formal and informal hedge pruning?

Formal hedges have a strong structural element – straight lines, crisp edges and a geometric look that’s created by regular pruning. Informal hedges rely less on rigid structure; they’re allowed to grow in a looser, more natural style, with selective pruning just to maintain their shape and size.

Q. What are the most common mistakes to avoid when pruning?

Common errors usually involve timing, tools or technique. Heavy pruning at the wrong time of year can stress plants and leave them vulnerable to pests and disease [see, ‘The how, what and when of hedging’, page 45]. Using the wrong tools – or blunt blades – tears foliage instead of making clean cuts, which looks unsightly, weakens the plant, and increases the risk of infection.

Q. What are some tips for pruning tall (2.5m-plus) hedges?

Safety comes first: always wear the right protective gear, use equipment according to the manufacturer’s instructions, and be sure you’re physically up to the task. For the best results, prune with the grain (in harmony with the plant’s natural growth lines) in an upward motion – never against it – to achieve clean, healthy cuts.

Q. How do I encourage dense, bushy growth rather than sparse or leggy growth?

This type of growth starts with choosing the right plant for the location – considering aspect, climate and soil. Dense growth is promoted and maintained through regular pruning and fertilising, and managing pests.

Q. Can pruning help prevent pests and disease?

Pruning is beneficial to help control pests and disease and prevent their spread. Removing infected areas of plants limits the spread to areas that are in good health.

Q. Do certain hedge plants respond better to pruning than others?

Most plants that are suitable for hedging will respond well to pruning.

TOOLS + TECHNIQUES

Q. Which tools are best for achieving clean, precise cuts on different types of hedge?

This varies with the type of hedge and the size. Our go-to machinery is a battery-powered, long-reach hedge trimmer.

Q. What’s the safest way to cut back an overgrown hedge without harming it?

Make sure you have the right equipment, and are pruning at the right time of year.

Q. Is it better to trim a little and often, or do a big cut once or twice a year?

It really depends on the plant and the look you’re aiming for, but in most cases trimming a little and often is best. Regular light pruning keeps hedges denser, tidier and healthier, while a single heavy cut once or twice a year can leave them looking bare and stressed. Formal hedges benefit from frequent clipping to maintain their sharp lines, whereas informal hedges are usually fine with an occasional trim to keep their natural shape.

Q. Should hedges with large leaves be pruned in a different way to those with small leaves?

Not usually. The main difference is in the appearance: hedge plants with tiny leaves, such as Pittosporum ‘James Stirling’, often form very dense, compact screens where any uneven cuts show more easily. This means they need a little extra care and precision to keep them looking neat, while large-leafed varieties, such as Magnolia ‘Little Gem’ and M. ‘Teddy Bear’, are often more forgiving.