Pittosporum Leaves Curling

Pittosporum is one of the most useful evergreen shrubs and small trees you can grow in a British garden. The feathery, wavy-edged foliage of Pittosporum tenuifolium (kohuhu) and its many cultivars gives hedges and borders a lightness that clipped box and yew simply cannot match. From Cornwall to Edinburgh, and across much of Ireland and Wales, gardeners rely on pittosporum for year-round structure, as a windbreak, and increasingly as a box blight alternative. The purple-leaved 'Tom Thumb', the silver-edged 'Silver Queen', and the white-variegated 'Irene Paterson' and 'Garnettii' all have devoted followings.

When the leaves start to curl, pucker, or distort, it can be alarming, particularly if the plant is doing important work in the garden as a hedge or specimen. The good news is that the cause is usually identifiable from a quick inspection, and most cases are either manageable or self-resolving.

Cold wind and frost damage (the most common UK cause)

Pittosporum tenuifolium is what gardeners and the RHS classify as borderline hardy. It tolerates light frost without drama, but extended periods of hard frost, and particularly persistent cold drying winds, can cause real damage. The characteristic symptom is leaf curl along the margins, sometimes accompanied by browning that starts at the tips and edges and works inward. In a severe winter the leaves may drop entirely. Worst affected are plants in east-facing or exposed positions, recently planted specimens whose roots have not yet established properly, and the variegated cultivars.

The silver and white-variegated forms, 'Silver Queen', 'Irene Paterson', and 'Garnettii', are noticeably less cold-tolerant than the plain green species. If you grow any of these in the midlands, northern England, or an exposed garden, you should expect some leaf curl and tip damage after a hard winter and should plan for it by choosing a sheltered south-facing position, ideally against a warm wall.

After a very cold winter a pittosporum can look completely dead. Before you remove it, scratch the bark on a main stem near the base. Green tissue underneath means the plant is alive. Cut back dead wood to the first visible live buds, give the plant a feed of a balanced fertiliser in spring, and keep it well watered through the following growing season. New growth usually pushes from the base or from low on the main stems from mid-spring onward, and recovery can be surprisingly complete even after plants that appeared entirely brown.

In northern UK gardens or any exposed site, grow pittosporum in the most sheltered spot available. A south- or west-facing position against a wall or fence, or in the lee of a larger windbreak, makes a significant difference to how the plant copes with cold winters.

Aphids (pittosporum aphid)

If the curling is concentrated on the youngest shoot tips rather than spread across the whole plant, and if you notice a sticky deposit on leaves or on surfaces beneath the plant, suspect aphids. The pittosporum aphid (Myzus pittospori) is a specific pest that feeds in dense colonies on new growth. The leaves curl tightly around the colonies, which makes the insects easy to miss on a casual inspection. Pull back a curled leaf and look on the underside for clusters of pale green or yellow-green soft-bodied insects.

As the colony grows it produces sticky honeydew. Ants running up and down the stems are often the first sign. The honeydew soon becomes colonised by sooty mould, a black fungal coating that further reduces the plant's ability to photosynthesize and looks unsightly. The combination of puckered shoot tips, stickiness, ants, and black sooty coating is a reliable diagnostic picture for aphid infestation.

Aphid infestations are most common in mild spring weather when soft new growth is developing. Treatment options include a strong jet of water to dislodge the colonies, insecticidal soap, or pyrethrum-based spray, applied to both sides of affected leaves. Natural predators including ladybird larvae, lacewings, and parasitic wasps will arrive once a colony is established, and a mid-season infestation on an otherwise healthy plant often resolves with minimal intervention.

Other causes of leaf curl on pittosporum

A third cause to be aware of is pittosporum leafminer (Phytomyza pittosporiphaga). The larvae tunnel through leaf tissue rather than feeding on the surface, leaving irregular pale blotches or winding tracks visible when you hold the leaf to the light. Affected leaves may also show rolled or distorted edges. It is rarely severe enough to threaten an established plant. Remove and bin affected leaves (do not compost them) and maintain vigorous growth with good feeding and watering.

Scale insects can appear as brown barnacle-like lumps on stems and the undersides of older leaves, accompanied by sticky honeydew and sooty mould. They are treated by scrubbing off with a soft brush or by applying a plant oil-based spray. In coastal gardens, salt spray from strong onshore winds can scorch leaf margins and cause curling. This typically affects only the outer, most exposed growth and the pattern follows the prevailing wind direction.

On variegated cultivars, watch for shoots reverting to plain green. These are not a disease, but vigorous plain green growth will outcompete the variegated form if not removed promptly. Cut reversion shoots back to their point of origin as soon as you notice them.

Waterlogging in heavy clay soils can cause root rot, which shows as general wilting, yellowing, and leaf drop rather than leaf curl specifically. Pittosporum needs well-drained soil. If you are on clay, improve drainage before planting or grow in a raised bed.

Pittosporum in the UK garden

Pittosporum tenuifolium grows to 5 to 10 metres as a specimen tree in the mildest UK gardens, particularly in Cornwall and along the west coast and the south and west of Ireland, where plants have reached significant size and become important landscape trees. Across most of southern and western England, Wales, and all of Ireland it makes a superb hedging plant, growing faster than box and showing none of box's vulnerability to box blight or box tree moth. The naturally wavy-edged small leaves produce a hedge with much more visual movement and lightness than clipped evergreens with flat rectangular leaves.

The fragrant small flowers, produced in late spring, are another bonus often overlooked by gardeners who grow pittosporum purely for its foliage. P. tobira (Japanese pittosporum) takes this further with showy clusters of white gardenia-scented flowers, though it is less cold-hardy than tenuifolium and best suited to sheltered coastal gardens or a south-facing wall. P. crassifolium (karo) is particularly wind-resistant and is widely used as a coastal windbreak in the south-west.

The foliage of all pittosporum species is highly valued by florists and flower arrangers. If you grow a hedge or substantial specimen, the prunings from an annual clip provide excellent long-lasting cut foliage.

Frequently asked questions

Which pittosporum cultivars are hardiest?

Plain green forms of Pittosporum tenuifolium are the hardiest. The species itself and green-leaved selections cope well in most UK gardens outside the far north. Variegated cultivars such as 'Silver Queen', 'Irene Paterson', and 'Garnettii' are noticeably less cold-tolerant and are more likely to suffer leaf curl and dieback in hard winters or exposed positions. If you garden in the north of England or Scotland, stick to the plain green species or grow any pittosporum in a sheltered south-facing spot.

Can I use pittosporum as a replacement for box hedging?

Yes, pittosporum is one of the best alternatives to box where box blight is a problem. Pittosporum tenuifolium grows faster than box, responds well to clipping, holds a dense evergreen form, and is completely unaffected by Cylindrocladium box blight or box tree moth. It is not as bone-hardy as box, but in the south and west of the UK, coastal areas, and sheltered gardens across much of England, Wales, and Ireland it performs very reliably as a formal or informal hedge.

Why are only the young shoot tips of my pittosporum curling?

Curling and distortion concentrated on new shoot tips, especially if accompanied by sticky residue or a black sooty coating, almost always means aphids. The pittosporum aphid (Myzus pittospori) congregates in dense colonies on young growth. The leaves curl inward around the colony, making it easy to miss the insects at first glance. Pull back a curled leaf and look for pale green or yellow-green aphids clustered underneath. Treating early, before the sooty mould sets in, is much easier.

My pittosporum looks dead after a cold winter. Should I remove it?

Wait before removing it. Pittosporum tenuifolium can look completely dead after a severe winter, with brown papery leaves and brittle twigs, yet the root system and lower woody stems remain alive. Scratch the bark on a main stem near the base: if the tissue beneath is green, the plant is alive. New shoots typically push from the base or from low on the main stems from mid-spring onward. Cut dead top-growth back to where you see live buds, feed with a balanced fertiliser in spring, and water regularly through the first growing season. Recovery can be surprisingly complete.

What is causing pale blotchy patches and rolled edges on pittosporum leaves?

Irregular pale or silvery blotches combined with rolling leaf edges are the signature of pittosporum leafminer (Phytomyza pittosporiphaga). The larvae tunnel within the leaf tissue, leaving winding or blotchy mines visible when you hold the leaf to the light. It is rarely severe enough to cause serious harm to an established plant. Remove and bin (do not compost) heavily affected leaves and keep the plant growing vigorously with adequate water and feeding. No chemical treatment is generally needed.