Coastal Rosemary Westringia fruticosa Zena

Zena is the fine leaved end of the coastal rosemary range, a tight selection with small grey-green leaves in whorls of three that clips into a clean face and holds it. White flowers with faint markings in the throat come heaviest in spring, then tick over through the rest of the year. Nothing about it is related to the rosemary in your kitchen: the leaves carry no scent and no culinary use. It is grown for low formal hedging, native edging, and mass planting against paving and paths.

Sun, sand and soil that never dries out

It handles the conditions that break most low hedging plants: salt wind, sand, reflected heat off paths and driveways, and long dry spells once the roots are down. Full sun, and plants set about 40 to 50 cm apart for a low hedge so the row closes into a single shape. What kills it is water it never asked for. In heavy soil that stays wet, or in a bed on an irrigation system running with lawns and annuals, the roots rot, the plant yellows and thins, and it eventually collapses open at the base. Raise the row on a mound where the ground is clay, work coarse material through the planting soil, keep mulch off the stems, and put it on its own irrigation station if the garden is watered, or on no station at all once it is established. Frost is handled in most temperate gardens, and it recovers well from wind burn on exposed sites. Growth is moderate, which works in favour of a formal hedge, since fewer cuts a year are needed to hold a line, and the plant accepts shaping from its first season in the ground.

Choosing between the three coastal rosemaries

Zena is the one to specify when the hedge has to look sharp, because the small leaf takes a clean edge and shows the cut line, which the larger leaved forms cannot match. Jervis Gem is a similar size but flowers mauve rather than white, so it is the pick where flower colour is doing work in the planting. The straight species, Westringia fruticosa, is taller and looser and belongs on batters, boundaries and large informal hedges, and it comes in far larger grades. Between the two compact forms, the test is viewing distance: at a path edge or entry, read from a step away, the fine leaf of Zena looks sharper, while along a driveway seen at speed, the mauve flush of Jervis Gem does more. See all three in the westringia range.

Shearing a tight hedge without going too far

Shear lightly and often, starting in the plant's first season, and time the main cut after the spring flush so you are shaping fresh growth rather than removing buds. Always keep leaf below every cut. Westringia reshoots poorly from bare old stems, so let the cut line move outward slightly each year rather than going back into the same woody frame, and a hedge that has already gone bare inside is better replaced than renovated. Feed sparingly in spring, since soft growth from heavy feeding will not hold a clipped edge. Water through the first summer while the root system is going down, then cut back to rainfall on all but the driest sites.

Choosing a size

This plant is available in 3 sizes, from 140mm up to 300mm, priced from $16.95 to $88.95 per plant. The size shown is the pot the plant arrives in, which is the rootball, not the height of the plant. These are younger plants, priced for planting in quantity, and they establish quickly once in the ground. Not sure which to choose? Read our guide to coastal planting.