Screening a narrow space: plants for beds under a metre wide

The hardest screening job in a suburban garden is the narrow one: a side passage a metre wide, a strip between driveway and fence, a bed against a boundary wall with a path in front. Standard screening plants either bulge into the walkway or get clipped so hard on one face that they thin and die back.

Choose for habit rather than height, and use shape techniques where no plant is narrow enough.

Match the plant to the actual width

Measure the usable bed width, then subtract what you need to walk or drive past. What is left is your budget. Natural width is not negotiable by pruning: you can hold a plant tighter than its habit only by fighting it forever, and a face clipped hard never fills out again.

Under 60cm is climber or espalier territory, or columnar plants with everything else kept clear.

Around one metre opens up the naturally narrow cultivars, the sweet spot for most side boundaries.

1.5 metres or more and standard screening plants work at close spacing.

Narrow at head height is not narrow at ankle height

A columnar plant is selected for a tight crown. Underneath it still builds a trunk and a root flare. Coast banksia Sentinel is the clear case: tight crown, proper tree trunk at the base. In a 700mm bed edged with a concrete mowing strip, the flare lifts the concrete long before the foliage does.

The naturally narrow performers

Evergreen natives

Among lilly pillies, Straight and Narrow is what its name says: small leaves close to the stem on an upright frame, so a row closes into a green wall instead of pushing over the path. Pinnacle stays dense from low down rather than going bare at the base the way older Syzygium selections do. Both were selected for psyllid resistance, which matters more at arm's length than across a lawn. Neither is a dry site plant, and a strip against a hot wall is where a lilly pilly sheds leaf from the bottom.

In a metre of full sun, Callistemon viminalis SLIM holds a column of fine weeping foliage from the base up. It needs light on both sides; against a shaded wall it thins on that face and stays thin. The rest of the bottlebrush range wants a deeper bed.

For a waist high screen, Grey Box clips into a low formal shape on one or two light shears a year. It is a coastal specialist, and wet heavy soil explains most single deaths out of a westringia line.

Formal evergreens for a clipped face

Green Rocket is the workhorse. Upright with short lateral branching, at 500mm centres it makes a green wall about the width of a garden bed rather than a hedge, and it takes a hard renovation cut back into wood and reshoots, which most narrow formal plants will not.

Sky Pencil suits a doorway or a large pot, a slim vertical that stays upright with barely any pruning. Heavy wet soil kills it, and dry inland summers scorch it.

Italian Cypress gives the most height for the least ground here, though not in a strip under about 1.2 metres, and at 1m to 1.2m centres the columns knit into one dark line, high rather than low. Drainage decides whether it lives: a bed catching roof runoff, or inside a lawn irrigation zone, will finish it. It will not reshoot from brown interior wood, so any hole you cut stays cut.

On a humid east coast fence line, especially a shaded one, Illawarra Plum is sounder. It takes part shade without thinning from the bottom, copes with humidity, salt wind and root competition, and reshoots from older wood. Space it 750mm to 1m. Young stock is frost tender, and the soft plums stain a pale path.

The deciduous option

Ornamental pears give the tightest deciduous column in Capital, useful along a driveway where you want summer shade and winter sun over a clear trunk. A solid screen goes in at 2m to 3m apart, so it answers a boundary rather than a side passage. Pear and cherry slug is the failure mode, grazing the leaf surface and leaving the row brown by midsummer. Choosing an ornamental pear compares the shapes; topiary and standards covers pre-trained stock.

Comparing the main candidates

Your district narrows the list further

Brisbane and the northern rivers: humidity is the filter. Cool climate conifers sulk, Illawarra plum and the lilly pillies do not. Watch soft new growth in the myrtle family for myrtle rust, and water at the base.

Melbourne's western suburbs, on basalt clay, are where Italian cypress and Sky Pencil die over winter rather than in summer. Mound the row above grade and backfill with native soil, or take Green Rocket instead. See planting into clay.

Canberra, Orange and the Southern Highlands: frost decides, and young Illawarra plum is out. Capital pear and the columnar conifers answer it. Clipped upright hornbeam holds tan leaf through winter, though Fastigiata is narrow while young and broadens into an oval with age. Conifers for screening and structure covers the rest.

Behind the Perth coast, on calcareous sand, the ground is alkaline and holds no water. Grey Box and Western Australian melaleucas such as Narrow Nessie cope. Acid lovers like loropetalum come up yellow between green veins against a limestone wall.

When no plant is narrow enough

Climbers on a frame need only the depth of the trellis. Star Jasmine gives a dense evergreen curtain with perfume at about one per metre. It twines and does not self cling, so tie the leaders onto the lowest wire and run them sideways; a plant left to bolt for the top leaves a permanent bare strip along the bottom. Hardenbergia gives late winter flower on a lighter frame. Mount the frame on battens with 50mm of air behind it; climbing plants for fences and pergolas covers how each type attaches.

Espalier holds a plant to perhaps 300mm of depth. Olea europaea Manzanillo Espaliers arrive with years of shaping done, so the job is holding the plane: wire them up as they go in, and check the ties each season before they bite into thickening wood. Ripe fruit drops and stains. On a shaded wall a sasanqua from the camellia range espaliers flat and flowers through autumn.

Pleaching answers the commonest brief of all: blocking a neighbour's upper window without losing the side garden. Clear trunks carry a flat clipped panel above fence height, and the ground below stays open. Ficus microcarpa Flash Pleached is field trained for exactly this, but read the root note. Hillii figs lift paving and find drains, some councils restrict them, and a side passage over a slab or sewer line needs a root barrier first. The rest of the figs and ficus range carries the same caution. In cool districts, pleach pears or hornbeam instead.

Spacing and setting out

Work in centres, trunk to trunk, and count a plant at each end of the run. Crowding a row because the bed is thin gives plants that compete and go bare at the bottom.

Set the row 300mm to 400mm off the fence. That gives access to the back face, keeps wet foliage off the palings, and puts roots into soil instead of boundary rubble. In a bed under 700mm the offset is most of your width, which is why side passages so often end up with a climber.

Planting into a narrow bed

A narrow root run makes preparation matter more than in an open border. Cultivate the whole strip as a trench rather than digging separate holes, so growth evens out along the line, and put irrigation in first. Retrofitting drip line into a closed screen against a fence is miserable work.

Dig a test hole before you order. Builders leave rubble and mortar along boundaries, and lime leaching from a slab or path edge lifts the pH against the concrete. A strip between a path and a wall also gets almost no rain: the wall throws it one way and the eaves take the rest.

What goes wrong in a narrow bed

One sided light. A plant lit from one side leans and thins on the dark face. Trim both faces from the first year and keep the sides slightly tapered so light reaches the base.

Reflected heat. A bed against a north or west wall bakes. Thuja occidentalis smaragd is the clearest casualty: let the root zone dry hard through a heat wave there and whole flanks brown off, and the scar stays.

No air movement. Squeezed against a fence with nothing moving, Green Rocket picks up powdery mildew and scale, then sooty mould follows until the hedge face goes grey and sticky. Indian hawthorn in that corner gets entomosporium leaf spot, blotching the leaves purple to dark red and stripping them from the base upward.

The hard cut on the path side. A screen left to bulge and then cut flush with the boundary is where most narrow plantings are lost. Green Rocket and Illawarra plum forgive it. Italian cypress and thuja will not, and westringia and Indian hawthorn are slow and patchy about it.

What to plant at the base

A low band in front of the screen hides the trunks, keeps weeds down and stops mulch washing onto the path. It has to be clump forming rather than spreading, which is why mat rush, the clumping flax lily selections and liriope are the usual answers. Mondo grass runs on stolons into a carpet, which is not what holds an edge. Keep them 300mm clear so the line trimmer never reaches the base of the hedge. One screen and one edge is the whole design.

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Related ranges: Buxus and box hedging, Conifers and cypress, Climbing plants.