A hedge is one of the most common practical questions a New Zealand garden throws up, usually some version of "what do I plant along this boundary that will actually grow into something useful before we sell the house." Native options tend to get passed over in favour of imported standbys like box or photinia, which is a shame, since several natives grow at least as fast, cope far better with wind and salt, and need less fuss once established.
Griselinia (kāpuka) is the classic fast choice for a reason. It's rated low-water and full-sun in this site's own plant data, grows up to around 60cm a year once established, and its glossy, pale-green leaves form a genuinely dense screen. It's also one of the most wind- and salt-tolerant options going, which is exactly why it turns up so often along exposed coastal boundaries where a lot of other hedging simply struggles.
Kōhūhū (Pittosporum tenuifolium) grows even faster again, up to around 75cm a year, and is also low-water and full-sun once settled in. What sets it apart is the sheer range of cultivars available: wavy-edged leaves, bronze, silver-variegated and near-black foliage forms all exist within the same tough, easy species, which makes it possible to get a genuinely distinctive-looking hedge without stepping outside a plant that's known to perform reliably.
Corokia is a different tool for a different job. It's compact (this site's data has it topping out around 2m, spaced closer than the taller options) with small, twiggy, often silver-backed foliage, and it suits a low clipped border or edge far better than a tall privacy screen. Like griselinia and kōhūhū, it's rated low-water and full-sun, so it slots into the same low-maintenance planting plan without needing separate care.
Karo is the one to reach for on an exposed site that griselinia alone doesn't quite suit: broader, leathery leaves, the same low-water, full-sun, wind-tolerant profile, and a reputation as one of the tougher coastal screening plants available. It's commonly planted alongside griselinia and flax as a living windbreak on exposed Wellington sections for exactly this reason.
Tōtara is the slow-but-permanent option, and worth knowing about even though it won't win any speed contest against the others. A clipped tōtara hedge is a genuine New Zealand gardening tradition, taken on by gardeners who want a dense, formal, extremely long-lived hedge rather than the fastest possible result. It's rated low-water and full-sun like the rest, and once a clipped tōtara hedge is established, it holds its shape and density for decades with minimal ongoing input.
Whichever species you choose, hedge spacing is tighter than the specimen spacing this site's plant pages list for a free-standing, open-grown plant. Those figures assume one plant with room to spread on every side; a hedge wants neighbouring plants knitting together into a single line, so planting at roughly half that specimen spacing is the standard approach for a genuinely dense result. Plant in autumn or spring so roots get a full cool season to establish before the first summer, and start trimming while plants are still young rather than waiting for them to reach full height first: an early trim encourages the bushy, branching growth that makes a hedge actually dense, instead of a row of leggy individual plants that only fill in near the top.
Those figures assume one plant with room to spread on every side; a hedge wants neighbouring plants knitting together into a single line, so planting at roughly half that specimen spacing is the standard approach for a genuinely dense result.