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Best uses

Best used as shelter planting or clipped as a hedge as it is so hardy. It is very resilient to wind and salt spray as these conditions make it hard for other species to establish.

Physical characteristics

A bushy fast growing evergreen native which grows to around 5m by 4m.

Flowers and foliage

Grey-green oval leaves are covered on the underside with fine white hairs. Clusters of burgundy flowers bloom through spring to early summer and are highly scented at night. Hard green capsules follow the flowers developing into seed pods that split to expose shiny sticky black seeds in a yellow pith in late autumn.

Preferred site

Prefers full sun or partial shade with free-draining soil. It can also tolerate coastal conditions and drought. This pittosporum is an early coloniser and is able to withstand high winds and salt spray so is great for tricky situations.

Preparation for planting

Always choose healthy well grown plants and plant after autumn rains. Before planting ensure the root ball is saturated and remove the planter bag or pot with minimal root disturbance. Trim any broken roots and plant at the same level as in the container. Dig a hole twice the diameter of the root ball and firm in and water once planted. Make sure plants are watered well until established if planting in a drier period. Plant with some general slow release fertiliser and then every spring apply an organic based fertiliser such as blood and bone at a handful per square metre as new growth begins.

Maintenance tips

Mulching helps to conserve soil moisture but keep mulching material away from plant stems. Trim the tops of the plant in late summer/autumn to prevent them from getting leggy.

Karo plants are susceptible to attack by Pittosporum chemid, an insect which sucks sap, causing loss of vitality and disfigured leaves. This can be controlled by spraying with an insecticide or a mixture of sunlight soap and water. Be sure to spray the underside of the leaf, because this is where the insects attack.

Karo do not need to be potted on from the root trainers. Trim the tops of the plant in late summer/autumn as they approach 30 cm in height. This stops them from getting leggy. Leggy plants do not grow as well as more compact forms when they are planted out, so regular trimming will help them establish. The root-ball sometimes dries out despite the surrounding soil being moist; direct water down the plant stem to saturate the root-ball. The first summer and autumn after planting is critical for young plants; water thoroughly during dry periods.

Mulching helps conserve moisture and suppress weeds; organic materials such as sawdust and bark contribute to soil structure as they decompose. Keep mulching material away from plant stems. Pests and diseases can have serious debilitating effects on young plants; check regularly. Check stakes and ties for chafing and constriction and remove as soon as plants are strong enough to withstand winds without damage. Except on very fertile soils, an annual light dressing (50g/m2) of general purpose fertiliser in spring is beneficial. Sprinkle evenly and work into the top 2 to 3cm of the soil, taking care not to damage surface roots.

Prune young hedges in their first year after planting to ensure even, dense growth. Hedges planted in autumn should be cut back by half during late spring. Trim again lightly in late summer. During the second winter (or in early spring) trim moderately to remove half the previous seasons new growth. Feed hedges at least once a year with a balanced fertiliser, ideally in early spring. Keep your hedge looking good with regular trimming. Fast growing hedges benefit from more frequent trimming. Avoid heavy pruning in autumn, as this promotes soft new growth more susceptible to frost damage. Best pruned with secateurs. Hedges should be shaped so they are narrower at the top than the base. This allows more light to reach the hedge sides, prevents it from becoming top heavy and unstable, and is easier to maintain.

A handful of an organic-based fertiliser per metre of the hedge will be beneficial.

Ecological and biodiversity benefits

Often an urban weed because its fruits/seeds are avidly taken by birds and dispersed widely. Tui are particularly fond of the nectar they obtain from the flowers.

Pests and diseases

Relatively free of pest and disease. It can get attacked by Pittosporum chemid insect which sucks sap causing loss of vitality and disfigured leaves. Treat by pruning the affected areas or treat with neem oil.

Location at Auckland Botanic Gardens

Native Identification Trail

Interesting facts and tips

Native habitat is coastal and offshore islands. Favouring steep slopes cliff faces bolder beaches rock stacks and the margins of petrel burrowed land. Sometimes forms major canopy dominant on offshore islands and on occasion can be a significant component of dune forest. Often an urban weed because its fruits/seeds are avidly taken by indigenous and exotic birds and dispersed widely.