How to Choose a Screening Tree in Australia

Most screening plantings fail because the species was chosen before the problem was measured. Someone sees a photo of a tall green wall, buys twelve of whatever the label said was fast, plants them a metre apart, and four years later has a row of bare legs with a clear view of the neighbour's bathroom window through the middle of it. Screening is a geometry problem first and a plant problem second. Get the geometry right and the plant list almost writes itself.

Work out the height you actually need, not the height you want

Stand where you sit. Not where the plant will go, and not at the fence. Sit in the chair on the deck, or stand at the kitchen sink, and have someone hold a broom or a length of pipe at the fence line while you call out where the top needs to be to block the thing that bothers you.

The answer is usually lower than people assume, because sightlines work in your favour. If the offending window is 5m up and 12m away, and you plant 3m in from the fence rather than on it, a 4m screen can block it completely. Every metre closer to your eye is a metre of height you do not have to grow. That single adjustment saves years and stops people buying a 15m tree for a problem a 5m tree solves.

It also stops the most expensive mistake in Australian gardens: planting a forest giant against a fence because it grows fast. Lophostemon confertus, Eucalyptus and Ficus are all fast, and all of them will be a serious problem on a suburban boundary within a decade.

Density: what actually makes a screen opaque

Height gets you nothing if you can see through it. Density comes from three things: branch habit, leaf size and whether the plant holds foliage to ground level.

• Branching habit. Species that branch low and often, like Syzygium, Viburnum and Photinia, screen from the ground up. Species that self prune to a clear trunk, like Tristaniopsis or most eucalypts, will eventually screen only at canopy level.
• Leaf size and overlap. Small overlapping leaves block more light than the same leaf area in a few large leaves. This is why Waterhousea reads as a solid wall and a large leaved fig does not.
• Light at the base. Nearly all screens thin at the bottom if they are shaded there. If you have a paling fence, the bottom 1.8m is already solid, so choose a species that carries its density from 1.8m up and stop worrying about bare legs.

Be honest about width too. A screen that reaches 8m tall will want to be 4 to 5m wide unless it is a naturally narrow cultivar or you commit to pruning it twice a year forever.

Evergreen or deciduous

In Australia evergreen wins for screening almost every time, because privacy is a year round requirement and winter is when you spend most time outdoors in the south. The exception is a deliberate one: an ornamental pear or a crepe myrtle on the northern side of a house, chosen so it screens through summer and lets winter sun into the living room. That is a real design decision and a good one, but it only works if you accept the plant is transparent for four months. We go through the trade-off in detail in evergreen versus deciduous screening.

Roots, pipes and the boundary itself

Sewer and stormwater lines usually run along or near boundaries, which is precisely where screening goes. Before you plant, find your sewer diagram, note the stormwater run and check for a retaining wall footing. Then apply the setbacks.

• Keep any tree with a mature height over 8m at least 3m from a sewer or stormwater line, or install a root barrier 600 to 900mm deep between the two.
• Keep large trees 2m clear of a retaining wall footing, and never plant one on the uphill side of a low wall that was not engineered for surcharge.
• Never plant Ficus, Populus, Salix, Melaleuca quinquenervia or Schinus near services. No pruning regime fixes a fig near a pipe.

Also check the boundary rules. Queensland and New South Wales both have neighbour and tree legislation covering overhanging branches, encroaching roots and obstruction of sunlight or views, and councils in both states have their own vegetation controls. Two minutes on your council website before you buy is cheaper than a dispute. Our guides to planting near a boundary fence and trees that will not wreck your pipes cover both issues properly.

Spacing and how many plants you need

The commonest error is planting too close, because a tight row looks better on day one and worse forever after. Crowded screens compete for water, thin from the inside, and lose their lower foliage first.

• Clipped hedge under 3m: 800mm to 1m centres.
• Narrow columnar screen such as Syzygium 'Pinnacle': 1 to 1.2m centres.
• Informal screen 4 to 6m tall: 1.5 to 2m centres.
• Large screening tree 8 to 12m: 2.5 to 3.5m centres.
• Canopy trees used to block an upper storey: 4 to 5m centres, planted as a group rather than a row.

Divide the run length by the spacing and add one. A 12m fence at 2m centres needs seven plants, not six. If you want the full working, including staggered double rows for difficult angles, see our hedge spacing guide.

If the job is a clipped lilly pilly hedge rather than individual trees, and you are in South East Queensland or along the coast to Sydney, The Hedge Guys grow advanced hedging in three heights and will supply it, or supply and install it.

Species that actually work, by height band

2 to 4m, for fence line and narrow beds. Syzygium australe 'Resilience' and 'Backyard Bliss' are the psyllid resistant lilly pillies and hold density right down. Viburnum odoratissimum reaches 3 to 5m and is one of the fastest true hedges in the subtropics. Murraya paniculata sits at 3m with glossy foliage and heavy perfume. Camellia sasanqua at 3 to 4m is the best choice for a shaded south facing fence. Photinia 'Red Robin' works in cooler districts but resents humidity in coastal Queensland.

4 to 8m, the useful suburban band. Syzygium 'Pinnacle' holds 5 to 6m at only 1.5m wide, which is the answer for side access. Elaeocarpus eumundii reaches 6 to 10m with a naturally narrow crown and bronze new growth. Magnolia grandiflora 'Little Gem' at 4 to 5m and 'Teddy Bear' at 4 to 6m give a formal dark green wall with almost no pruning. Callistemon 'Kings Park Special' at 4 to 5m is hard to kill in poor soil. Bambusa textilis gracilis, a genuinely clumping bamboo, gives 6 to 8m of screen in a strip barely a metre wide.

8m and over, for blocking height. Waterhousea floribunda is the benchmark weeping screen at 8 to 12m in gardens, dense to the ground, forgiving of clipping. Acmena smithii and Syzygium luehmannii are similar in habit. Tristaniopsis laurina reaches 6 to 10m and tolerates hard urban conditions but lifts its skirt over time. Podocarpus elatus makes a dark, slow, very long lived screen. In cooler inland districts Cupressus 'Leighton Green' will do 10 to 15m but needs airflow and will not tolerate humid coastal summers.

Shrubby options for the lower band are gathered in our shrubs for privacy collection, and the full range across every height sits in privacy screening.

How much can you buy and how much do you have to grow

You can buy a real head start. Advanced stock at 100L and above will typically give you 2.5 to 3.5m on the day of planting, which for most fence line problems is roughly two thirds of the job done immediately. What you cannot buy is instant density between plants: they still have to grow together, and that takes one to three seasons depending on species and water.

If the problem is urgent, our mature plants for immediate privacy collection is the stock large enough to work from week one. If you are blocking a two storey neighbour specifically, read screening a two storey neighbour first, because that problem needs canopy trees placed by sightline rather than a hedge at the fence.

The first two summers decide everything

A screen that is watered deeply and infrequently for two years will outperform an identical screen that was watered lightly and often, every time. Run a dripline the full length of the row rather than watering individual plants, mulch 75mm deep and keep it 100mm off the stems, and do not fertilise heavily in the first six weeks. Prune lightly and early to build density rather than waiting three years and then cutting hard into bare wood, which most screening species recover from slowly and some never do.

Everything we supply is delivered free anywhere in Australia and planted by our own crew, spaced and set out on site, as one bundled price. That includes marking the row, preparing each hole and mulching the whole run. See how it works on our supplied and installed page.

Measure your sightline this week, decide your real target height, then shortlist two or three species from the screening range that suit your soil and aspect. Send us the fence length and the access width and we will tell you the spacing, the plant count and the size that gets you there fastest.