How many plants do I need for a hedge? - Plant Drop

How many plants do I need for a hedge?

This is the first question worth answering on a hedging job, because it sets the budget before anything else does. Space too wide and you have gaps that take years to fill. Space too tight and you have paid for plants that spend their lives competing with each other. The arithmetic takes a minute. The spacing judgement is where the job is won or lost.

The formula

For a straight run with a plant at each end:

Number of plants = (length of run divided by spacing) + 1

Spacing is measured centre to centre, from the middle of one plant to the middle of the next, not as the gap between pots or canopies. Measuring canopy to canopy is the most common way people end up ordering far more stock than the job needs.

The "+1" only applies if you want a plant at both ends. If the hedge butts into a wall or an existing hedge at one end, drop one plant. If it butts in at both ends, drop two.

You will rarely land on a whole number. Round the number of gaps first, then adjust the spacing slightly to fit the run rather than leaving a short offcut at one end. A line at an even 1.54 m reads as deliberate. A line at 1.5 m with a 0.5 m stub does not, and that stub stays visible for the life of the hedge.

Spacing is set by mature width, not by pot size

The pot a plant arrives in tells you nothing about how far apart it should go. A small pot and a large pot of the same cultivar want identical spacing, because they finish at the same width. The larger pot buys time, not density.

The working rule for a hedge that closes into a continuous face is to space at roughly half to two thirds of the plant's mature width. A shrub finishing around 1.5 m wide goes in at about 0.75 m to 1 m. One finishing around 3 m wide goes in at about 1.5 m to 2 m. If you intend to keep the hedge clipped narrower than its natural width, space to the clipped width instead.

What you are building Approximate mature width Spacing, centre to centre Plants per 10 m
Low border or edging, held under 1 m 0.6 to 1 m 0.4 to 0.6 m 18 to 26
Mid height hedge, 1.5 to 2.5 m 1 to 1.5 m 0.6 to 1 m 11 to 18
Full privacy screen, 3 to 5 m 1.5 to 2.5 m 1 to 1.5 m 8 to 11
Tall screen or windbreak, 5 m and over 3 m and over 1.5 to 2.5 m 5 to 8
Avenue or tree line, canopy above head height Varies widely by species 4 to 8 m 2 to 4

Match the plant to the band before you fix a number. Across the hedging range, low border work is usually westringia, Indian hawthorn or lavender, softened rather than clipped with lomandra and ornamental grasses. The mid height band suits camellia sasanqua and the more compact shrubs. Full privacy screening is where lilly pilly does most of the work, with ficus where a formal clipped face is wanted. Above that, paperbark and bottlebrush make useful informal screens, and the avenue band is a tree job.

One caution on lilly pilly, the plant most often ordered without checking: the range runs from compact cultivars around 2 m to forms that make a 5 m or taller screen, and those want very different spacing. Confirm the cultivar before you divide anything.

A worked example: a 20 metre boundary

A 20 m rear boundary, clear end to end, with a plant at each end.

Target spacing Gaps Spacing you actually plant at Plants to order
0.75 m 27 0.74 m 28
1 m 20 1 m 21
1.5 m 13 1.54 m 14
2 m 10 2 m 11

The rows that matter for most screening jobs are 1 m and 1.5 m: 21 plants against 14 on the same 20 metres, so the tighter option is half as much stock again. On advanced sizes that gap is substantial, and what it buys is a hedge that closes perhaps a season or two earlier and is then permanently overcrowded.

Why planting closer does not close a hedge faster in the long run

The intuition is reasonable: less distance to cover, so it closes sooner. For the first year or two that holds, which is why close planting sells. What it ignores is that growth rate is limited by the soil volume, water and light each plant has to itself, not by the air between neighbours.

Root zones overlap long before canopies do, and once they do every plant in the line slows. A crowded hedge needs more water and feeding to hold the same growth, permanently. You pay twice: once for the extra plants, then every year in inputs.

The rest of the cost shows up later.

  • Hollow bases. Crowded plants shade each other's lower branches out, so the hedge thins from the bottom, which is the part you planted it for.
  • No replacement room. If a plant dies mid line there is no root space to establish a new one into, so the gap stays.
  • More pruning, sooner. A hedge at half its correct spacing needs cutting more often, and hard corrective cuts are risky on established plants.

Correctly spaced plants keep growing at their own rate for years longer, and by maturity that hedge is denser to the ground than the crowded one. Close planting is only defensible for a short term screen you accept you will thin.

What actually shortens the time to close

If the timeline is the constraint, spend the money here instead of on extra plants.

  • Buy larger stock. The most direct lever. Moving to semi advanced or advanced stock takes years off the wait, and on a 14 plant order that upgrade often costs less than the 7 extra plants.
  • Prepare the whole trench, not individual holes. A continuous strip lets roots run along the line. Individual holes in heavy clay behave like pots in the ground.
  • Water properly through the first summer. Deep and less often, on a line of drippers rather than by hand. This does more for closing speed than anything else you control.
  • Tip prune from the first season. The common mistake is leaving the hedge alone until it reaches full height, then clipping. That gives a leggy hedge that never fills at the base. Light regular tipping from year one builds density.

Five things that change your final number

  • Setback from the fence. Plant at least half the mature or clipped width off the boundary so the hedge is not growing through the fence or over the neighbour's side.
  • Gates, driveways and services. Measure the planted run, not the boundary. Subtract gate openings and crossovers, and keep clear of meter boxes and taps.
  • Corners. Place the corner plant first, then measure each leg out from it. Dividing the legs independently is how you get a bunched corner.
  • Curves. Measure along the curve with a tape on the ground, never the straight line distance. A gentle curve can add a metre or more across a long run.
  • Spares. Add one or two plants on any run over about 15 m. Matching a replacement into an established hedge later is difficult.

On double staggered rows: they close a little faster laterally, but they double the plant count and the water demand, and the inner row is usually first to thin because it is shaded from both sides. For most boundaries a single row at the correct spacing, in a larger pot size, is the better use of the same money.

Ordering for a boundary run

Our minimum order is $399 with flat rate delivery of $99 anywhere we service: QLD, NSW, VIC, SA, ACT and WA. We do not deliver to Tasmania or the Northern Territory. That suits this kind of job. Almost any boundary hedge clears the minimum, and the flat freight costs the same for 14 plants as for 21.

Measure the run, settle on the plant, take its mature or clipped width, divide, then order in one go. Buying a hedge in two batches months apart is how you end up with a line that never quite matches. Start with the hedging collection if you know the height you want, or privacy screening if the goal is blocking a specific sightline.

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 · Westringia · Camellias

Related ranges: Buxus and box hedging.

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