Coastal Rosemary Westringia fruticosa

On exposed sandstone headlands along the New South Wales coast, coastal rosemary grows in almost no soil with salt spray coming straight off the water, and that tells you most of what it will do in a garden. This is the full sized species rather than a compact selection, an upright grey-green shrub with fine leaves in neat whorls and small white flowers scattered over the bush for much of the year rather than in one flush. It does the heavy work: informal hedges, batters, median strips and coastal frontages.

Where it thrives, and the pruning cycle that ruins it

Full sun, free draining soil, and very little water once established. It takes sand, salt wind, reflected heat and thin poor ground, and is happier neglected than fussed over, but it dislikes wet heavy clay, so on a poor site raise the bed. For an informal hedge at knee to waist height, set plants roughly 60 to 75 cm apart. The way gardens actually lose this plant is a pruning cycle, not a pest. Left untouched for two or three years it grows tall, opens in the middle and goes woody at the base, and the natural response is to cut it hard. Westringia reshoots poorly from bare old wood, so a hard renovation cut leaves grey sticks that never fill in and the plant has to be replaced. Trim lightly and frequently from the day it goes in, always leaving leaf below the cut, and it stays dense to the ground for years. Frost in most temperate gardens is no trouble, and it tolerates the conditions of a median strip, which is why it turns up in so much roadside planting. Growth is moderate, so allow a season or two before a hedge line closes.

The species or one of the compact selections

This is the tallest and most open of the three coastal rosemaries here, the one for height, bulk and coverage across a batter or a boundary, and the only one in large advanced grades. Jervis Gem is a compact selection with mauve flowers, for low hedging where the species would be too tall. Zena has the smallest leaf of the three and holds the tightest clipped face, so it is the pick for formal edging. The test is what the planting has to do: to see over it to a view, the species will not stay low enough and a compact form is the answer, but to screen a fence, break wind or hold a slope, the species has the bulk. Compare all three in the westringia range.

Little and often with the shears

Trim after each flush of growth, taking a small amount every time rather than waiting for a big cut, and start in the first season while the plant is young. That builds density from the base and keeps flowering going, since it flowers on and off through the year rather than all at once. Feeding is rarely necessary and heavy feeding works against you, producing soft growth that flops and burns in salt wind. A light application of general fertiliser in spring is plenty on poor sand, and nothing at all on reasonable soil. In a mass planting, run over the whole area with a hedge trimmer twice a year rather than shaping plants one at a time.

Choosing a size

This plant is available in 10 sizes, from 70mm up to 100L, priced from $16.95 to $649.00 per plant. The size shown is the pot the plant arrives in, which is the rootball, not the height of the plant. The smaller pots hold younger plants that cost less each and establish quickly, which suits hedges, screens and mass planting where the plant count adds up. The larger sizes carry several more years of growth on the farm and give height and presence straight away, which is what you want for a single feature position or a screen that cannot wait. Not sure which to choose? Read our guide to coastal planting.