Griselinia Leaves Curling

Frost damage

Frost is the primary limitation on griselinia's usefulness as a hedging plant in the UK and the most common cause of leaf curling, browning, and plant death on this species. Griselinia littoralis is native to New Zealand, where it grows in coastal and lowland forest in a mild maritime climate, and its cold hardiness in the UK reflects this origin: it is genuinely reliable in mild coastal and western UK gardens, where the maritime influence moderates winter temperatures and prevents the sustained hard frosts that cause the most damage, but it is a higher-risk choice for inland and eastern positions where temperatures regularly drop well below minus five degrees Celsius. When frost damage occurs, the normally fresh, apple-green oval leaves turn yellow, then brown, curl, and drop. Light frosts cause damage to the newest, softest growth; hard frosts damage all the foliage and can kill the stems back to the main framework or to the root crown. A griselinia hedge that has been killed to the roots by a severe frost leaves a sudden and alarming gap that can take years to replace with a like-for-like hedge. The combination of frost and cold drying winds, which are common in exposed inland UK positions in late winter, is more damaging than still-air frost of the same temperature, as the wind removes moisture from the frosted leaves faster than they can be replaced from frozen roots.

Choose griselinia for hedging only in positions that do not regularly experience hard frosts below minus eight to ten degrees Celsius. In mild coastal gardens in Cornwall, Devon, Wales, and the west of Scotland, griselinia is one of the best fast-growing evergreen hedging options and grows reliably without winter damage. In colder inland gardens, alternatives including Prunus laurocerasus, Viburnum tinus, or Taxus baccata are more appropriate for a permanent, winter-reliable hedge. If griselinia is already established and suffers frost damage, do not cut back until late spring when the full extent of the damage is apparent and further frost risk has passed; the dead stems provide some insulation to the crown and any surviving growth below. A griselinia hedge killed to the base but with surviving roots often regenerates from the crown, and the fast growth rate of this species means recovery is quicker than with slower-growing alternatives.

Scale insects

Scale insects, particularly brown soft scale (Coccus hesperidum) and cushion scale (Pulvinaria species), establish readily on griselinia and can build up to damaging levels, especially on sheltered specimens that are well-established and providing consistent sap. The insects attach to the stems and the undersides of the smooth, oval leaves and feed continuously, producing honeydew that cascades down onto the leaf surfaces below and supports black sooty mould growth. The normally clean, bright apple-green appearance of griselinia foliage is particularly affected by sooty mould, as the contrast between healthy and infested portions is visually striking. In griselinia used as a formal hedge, scale insect infestations reduce the vigour of affected sections and can cause visible dieback that leaves gaps in what should be a solid screen. Because griselinia hedges are often planted in sheltered positions specifically chosen for their frost protection value, the warm, sheltered microhabitat these positions provide is also ideal for scale insect population development.

Inspect griselinia stems and leaf undersides each spring and treat any scale insect colonies promptly. Apply a fatty acid or neem oil spray in late spring when the crawler stage is active, directing the spray to all stem surfaces and leaf undersides. The smooth leaves of griselinia hold spray well, which helps contact efficacy. Repeat after ten to fourteen days. On accessible stems, wiping scale insects off with a damp cloth before treating for crawlers reduces the adult population. Annual clipping of griselinia hedges, which removes the outermost stems and exposes inner growth to more air movement, incidentally disrupts established scale populations on the clipped material.

Drought

Drought stress causes griselinia leaves to curl inward and lose the fresh, slightly translucent apple-green tone that is the species' most attractive characteristic, taking on a dull, yellow-green hue. Griselinia is reasonably adaptable to a range of soil conditions and is more drought-tolerant than its moist, coastal origins might suggest, but newly planted specimens and those in the first two to three seasons before their root system is fully established can suffer visible moisture stress in hot, dry summers. The smooth, relatively thin leaves of griselinia provide less protection against moisture loss than the thicker, waxier leaves of more drought-adapted evergreens. In coastal positions where griselinia most commonly grows in the UK, drought stress is rarely a significant issue as maritime humidity and generally moderate temperatures reduce water demand.

Water newly planted griselinia consistently through its first two to three seasons. Once established, griselinia manages most UK summers without supplementary watering. During prolonged dry spells, a deep watering at the root zone is more beneficial than frequent shallow watering. Apply a mulch at the base annually to retain soil moisture. Griselinia's characteristic apple-green leaf colour returns quickly once adequate moisture is restored.

Phytophthora root rot

Phytophthora root rot causes progressive decline and sudden death in griselinia planted in waterlogged or poorly drained soil. The water mould attacks the root system in oxygen-depleted, saturated conditions and spreads to the crown, with the above-ground symptoms appearing as the root damage becomes extensive: leaves yellow, curl, and drop, and sections of the hedge die back before collapse of the entire plant or hedge section. Griselinia planted in heavy clay without drainage improvement, or in low-lying positions where water accumulates after rain, is most at risk. Phytophthora losses in griselinia hedges can be difficult to distinguish from frost damage without examining the root system, but the presence of the reddish-brown discolouration in the stem bark at the base confirms root rot.

Plant griselinia in well-drained to moderately moist soil, incorporating grit into heavy clay and planting at or slightly above soil level. If phytophthora is diagnosed, remove the affected plants, improve drainage thoroughly, and allow the soil to recover before replanting. Replacing a griselinia hedge section that has died from phytophthora with another griselinia in the same position without resolving the drainage issue will produce another loss within a few seasons.

Wind scorch

Cold wind scorch causes griselinia leaves to brown and curl on the windward side of hedges and specimens in exposed positions. Griselinia is notably salt and wind resistant, which is why it is so popular as coastal hedging in exposed maritime gardens where more tender plants fail, but cold inland winds in winter, particularly those with a northerly or easterly origin, can desiccate the leaves faster than the roots can supply water, especially when the soil is cold or frozen. The damage is most severe on the outer, windward leaves of a hedge, while the protected inner leaves typically remain healthy. The wind resistance that makes griselinia such a good coastal hedging plant is effective against salt-laden maritime winds but less protective against dry, cold continental air frosts.

Plant griselinia where it has good shelter from cold north and east winds, or accept that some winter wind scorch is normal in exposed positions and plan to clip back scorched growth in spring. In coastal gardens, the natural salt resistance and wind tolerance of griselinia means wind scorch is rarely a problem. In inland positions exposed to cold winter winds, choosing a hardier, wind-tolerant hedging plant may be more appropriate than griselinia.

Frequently asked questions

Why are my griselinia leaves curling?

Frost damage is the most common cause of leaf curling and browning on griselinia in the UK, particularly in inland and more exposed gardens away from the mild coastal areas where it grows most reliably. Scale insects cause leaf curl, sticky sooty mould deposits, and reduced vigour. Drought stress causes the apple-green leaves to curl inward and lose their characteristic fresh colour in hot, dry conditions.

Is griselinia frost hardy in the UK?

Griselinia littoralis is moderately frost hardy, tolerating temperatures down to about minus ten degrees Celsius in a sheltered position. It is reliably hardy in mild coastal gardens in the south and west of the UK, where it is widely used as a fast-growing, wind-resistant evergreen hedge. In colder, more inland positions or in severe winters, it can suffer significant leaf damage or complete top-growth death, though the root system often survives and regenerates.

Why are my griselinia leaves turning brown?

Brown griselinia leaves most often indicate frost damage, where the normally bright apple-green foliage is damaged by cold temperatures in winter. Cold wind scorch causes similar browning on the windward side of hedges. Scale insect infestations cause the foliage to become coated in black sooty mould that dulls and discolours the otherwise clean leaves.

What is the best position for griselinia hedging?

Griselinia performs best in a mild, coastal, or sheltered urban position with well-drained to moderately moist soil in full sun to partial shade. It is particularly well-suited to coastal gardens where its salt tolerance and wind resistance are valuable. In inland positions subject to hard frosts, griselinia is a higher-risk hedging choice and alternatives such as Prunus laurocerasus or Eleagnus are more reliably hardy.