Planting for windbreaks and screening

Before you start

Planting trees and shrubs for windbreaks or screening can improve productivity, protect crops and livestock, and enhance the overall health and appearance of your property. Well-designed plantings also contribute to biodiversity and landscape resilience.

Read the guide to planning a revegetation project.

Benefits of planting windbreaks and screening

A good windbreak can slow wind speed up to 80% and helps to reduce crop and pasture moisture loss and stock stress. 

When positioned correctly, windbreaks function up to 20 times their height across the paddock, with best results within 10 times the height. For example, a 15m high windbreak will be effective for up to 300m but most effective within 150m. 

While the trees take up land and can rob adjacent crops and pastures for a distance equal to about twice their own height, they shelter a much larger area and the benefits far outweigh these losses. 

Windbreak design principles 

Best results are achieved when the windbreak is perpendicular (at right angles) to the problem wind. This offers the greatest resistance and distance benefit. As the angle decreases, so does effectiveness. 

A windbreak that runs parallel to the wind offers no protection. If it’s practical and the risk of localised frost is low, consider planting your windbreak in a curve, such as along an elevation contour, so there is always a portion of the break perpendicular to the wind. 

• A good windbreak should be around 40% porous, sparse enough to encourage the wind to flow through but dense enough to offer resistance and slow down the air speed.
• Give your plants room to grow. A minimum of 25m for a 4-row break. Tall, bushy plants cannot be achieved if plants are packed like soldiers on parade.
• Plant the outside rows with shrub species. This will provide low foliage cover and reduce the moisture and nutrient robbing effect of large trees on adjacent pastures and crops.
• Try to avoid gaps and short windbreaks as wind can deflect around the ends of the windbreak and increase wind turbulence.
• Plant losses should be replaced in the next planting season. A windbreak with holes is ineffective and may even cause wind tunnelling (a localised increase in wind speed).
• Because of the need for precise plant position, plant your windbreak using seedlings rather than direct seeding methods.

Main features of a windbreak design

• Outer rows of shrub species ensure uniform foliage cover at ground level.
• Trees species are in centre rows to minimise competition with adjacent pasture or crops and to minimise fence damage from falling branches when the trees are mature.
• Trees are 8m apart to allow canopy spreading and to reduce long-term competition. Note: trees and shrubs are alternated in the centre rows and the outside rows are offset against the centre rows. This ensures good foliage cover when looking across the windbreak.
• The 4m gap between the fence and planting rows allows reasonable access for maintenance.

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This four row windbreak is 30 metres wide and requires 1,000 seedlings per kilometre.

Variations

• The design could be compressed into a 25 m wide site by reducing all gaps by 1 m and still be reasonably effective.
• If adding an additional row, place the trees 12 m apart (T – S – S –T), to provide adequate space for maturity.
• Rows don’t have to be straight, consider planting curved rows to improve your planting’s effectiveness and create a more natural look.

What not to do

These yellow box and ironbark trees were planted to closely spaced to function as a windbreak. As the plants mature, they aggressively compete for nutrients, moisture and light. The result is loss of lower branches, stunted growth and patches of dead plants. 

The long term result of close plantings. Notice the patches of dead plants creating holes in the canopy and the loss of lower branches creating a potential wind tunnel at ground level. To repair the windbreak, the trees could be evenly thinned and rows of shrubs planted on either side. The felled timber could be left to increase wildlife habitat.

Planting for screening

There are several reasons you may wish to plant trees and shrubs for screening, such as: 

• visual barriers to block a view
• noise screens that reflect back offending noise
• screening buffers to filter spray drift from adjacent activities such as intensive cropping or horticulture.

Because of the need for precise plant position, plant your screening projects using seedlings rather than direct seeding.

Visual barriers

Structure visual barriers like a windbreak with the outside rows planted with shrubs to produce a low hedge-like cover.

Noise screens

The rows should be positioned to reflect the sound with space between to create a large baffle-like structure. 

• The wider the planting, the better. Aim for a minimum width of 30m.
• There should be at least three rows, with a large gap between rows. The suggested distance between rows for a noise barrier is approximately 12m.
• Rows contain gaps but are offset to prevent noise (and wind) travelling straight through the gaps.
• Use a good mix of trees and shrubs along your row to ensure good foliage cover from ground to tree height to block noise.

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Planting design for a noise barrier. A noise barrier should create a baffle-like structure to reflect back noise.

Spray drift buffers 

Screening that is designed to filter spray drift from adjacent activities such as intensive cropping or horticulture need to encourage airflow through the planting, not over it. 

• Spray drift buffers are generally sparser (approximately 30 to 50% porous)
• Use of a large variety of foliage types (fine to coarse foliage). This maximises the filtration of airborne particles.
• The wider the buffer, the better. Aim for a minimum width of 40m.
• Buffers also need to be as close as practical to the spray source. The further away, the less effective.

What not to do

The trees in this treeline have been affected by chemical spray drift from the adjacent cropped paddocks. Barriers must be wider than this to effectively filter spray drift and to survive in the long term. Careful plant species selection and placement is also required. 

Your next steps

Get advice on:

• plant species selection
• planning your on-ground revegetation works
• methods for planting seedlings.