Hedging plants for Australian conditions - Plant Drop

Hedging plants for Australian conditions

On a hedge, the plant choice, the spacing and the first two years of pruning matter more than anything else you do. Get them wrong and you have a row of shrubs with bare ankles, gaps where plants died, and a client asking why it does not look like the drawing.

Formal or informal: decide before you order

A formal hedge is clipped to a shape. It needs small leaves, short internodes and a naturally dense habit, and shearing two to four times a year for as long as it exists. Shear a large leaved plant and you slice leaves in half, the cut edges brown off, and the hedge looks scorched after every trim.

An informal hedge is a row grown close to its natural shape, tidied once or twice a year, and planted so the canopies knit together. It screens just as well, it flowers, and it forgives neglect. For most boundary work on Australian blocks that is the honest answer, and the privacy screening range is built around it. A 40 metre formal run is a recurring maintenance contract, so be realistic about what will get done.

Buxus: read this before you specify it

Box is still the default in a lot of garden plans, and for a low clipped parterre nothing else gives the same texture. It carries two problems worth stating plainly. Box blight is a fungal disease that defoliates from the inside of the plant outward, leaving bare stems with dark lesions. It spreads in humid, still conditions and travels on shears, gloves and clippings, and overhead irrigation that wets the foliage every evening makes it worse. Box psyllid is a sap sucking insect that distorts new shoot tips into small cupped rosettes; it rarely kills a plant, but it ruins the crisp outline that was the reason for planting box.

Box is also slow, so losing sections in year four means years of growing on to match the survivors. Where the brief calls for a tight, small leaved clipped edge, consider compact Indian hawthorn forms, small lilly pilly selections, or westringia where a grey green tone suits. None look identical to box; all are less likely to be pulled out in year five.

Coast, wind and low water: westringia and rhaphiolepis

Coastal sites punish the wrong plant quickly: salt laden wind burns soft foliage, sandy soils hold little water, and reflected heat off paving adds to the load. Westringia (native rosemary) is one of the few genuinely coastal shrubs that also clips well. It takes wind and salt exposure, wants free draining soil and full sun, and dislikes wet feet more than drought. The critical point is that it is a trim little and often plant: let it run unpruned for years, then cut hard back into bare old wood, and it often will not reshoot. Start shaping from planting. Browse the westringia range.

Rhaphiolepis (Indian hawthorn) is the workhorse for hot, dry, exposed positions: street frontages, car park edges, western walls. The leaves are thick and leathery, it needs very little water once established, and it flowers through spring. Because the leaf is medium sized rather than tiny, it looks better shaped informally than razor edged, and compact selections suit hedges to about chest height. See the Indian hawthorn range, and the low maintenance range for the understorey.

Shade and part shade: camellia sasanqua

Shade is where most hedging lists fall apart: sun lovers on a south facing fence go thin at the base and lean toward the light. The reliable answer is Camellia sasanqua. Against the japonica types it has a smaller leaf, a denser twiggier habit and better tolerance of direct sun, and it takes clipping well, which is why it is used so often as a formal hedge or espaliered flat against a fence. It flowers in autumn and early winter when little else does. Give it slightly acidic, free draining, organic soil, mulch kept off the trunk, and no digging around the shallow roots, and plant it at the level it sat in the pot.

Two honest limits: it will not thrive in dry, root filled shade under a mature eucalypt, where the problem is competition for water rather than light, and it is a good hedge rather than a fast screen. See the camellia range.

Height and screening: lilly pilly, done properly

Above about two metres, lilly pilly remains the standard: dense to the ground, evergreen, fast, and tolerant of hard pruning. First, match the cultivar to the target height. Named selections range from compact forms of about a metre to trees well over five, so a large growing selection on a 1.8 metre fence line commits you to fighting it forever. Second, psyllid, the cause of the pimpled new growth people associate with the group. Susceptibility varies a lot: Acmena types are generally less affected than many Syzygium australe forms, and several named cultivars have been selected for resistance. The lilly pilly range lists mature sizes on each product, so size the cultivar to the job.

Spacing by mature width

The working rule for a hedge that closes into a solid face is to space plants at roughly 40 to 50 per cent of the width you intend to maintain. Not the label width if you plan to clip it narrower, and not what looks right on delivery day.

Maintained width Single row spacing (centres) Typical time to close
0.5 m (low border) 300 to 400 mm 1 to 2 seasons
1.0 m 500 to 600 mm 2 seasons
1.5 m 700 to 900 mm 2 to 3 seasons
2.0 m 1.0 to 1.2 m 2 to 3 seasons
3.0 m 1.5 to 2.0 m 3 to 4 seasons
4.0 m and above 2.5 to 3.0 m 4 seasons or more
  • Tighter is not better. Crowded plants compete for water and root volume, and the row thins at ground level. Halving the spacing does not halve the time to close; it doubles the plant count and the water demand.
  • Set out with a string line. Hold the row far enough off the fence to walk behind it, and clear of pipes and footings.

Pruning: build the base before the height

The most common failure in domestic hedging is letting plants run up to target height untouched and only then starting to clip. By then the base is bare, and it stays bare, because light no longer reaches it. Tip prune from the first season instead: take the soft tips off the leaders and the side shoots, and each cut forces two or more shoots below it, which is how branch density is built. You lose a little height in year one and gain a hedge solid to ground level for the next twenty.

  • Prune the sides earliest. Side shear from the first season and let the top run up more slowly.
  • Taper the profile. The base should be noticeably wider than the top on anything above about 1.5 metres, or the hedge shades its own lower foliage out.
  • Little and often beats one hard cut. Two or three light trims a season keep a formal face tight; annual heavy cutting gives coarse regrowth and a lumpy line.
  • Know what reshoots from old wood. Camellia and lilly pilly generally recover from a hard renovation cut; westringia and many fine leaved natives often do not, so stage a big reduction over two or three seasons.
  • Time it sensibly. Trim after the main flush, after frost risk passes in cold districts, and never into a heatwave.

What size stock to buy

For hedging, buying big is usually the wrong call. Smaller stock in 200 mm or 250 mm pots establishes faster, roots out into the surrounding soil more readily, and trains into a dense base, and a row tip pruned properly will often overtake advanced plants installed at height and never structured. Order the whole run at once: plants added a year later never catch up, and the join stays visible.

Plant Drop ships farm direct to QLD, NSW, VIC, SA, ACT and WA on flat $99 delivery, with a $399 minimum order that suits hedging because you buy by the row. Start with the hedging collection, or work by site: westringia for coast and low water, Indian hawthorn for hot dry frontages, camellias for shade, lilly pilly for height.

Plants featured in this guide

Everything below is currently available farm-direct, with flat $99 delivery in QLD, NSW, VIC, SA, ACT and WA and a $399 minimum order.

Browse the full range: Lilly Pilly · Camellias · Westringia · Indian Hawthorn

Related ranges: Buxus and box hedging, Gardenias, Viburnums, Topiary and standards.

Not sure where to start? Browse the full range index, every collection and guide in one place.

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