Leaf burn is the damage Australian gardens produce more reliably than any other. A single 40°C day with hot northerly wind can scorch a plant that looked perfect the evening before, and the marks stay until the leaf is replaced. Knowing which kind of burn you are looking at matters, because sun, wind, salt, frost and fertiliser all leave slightly different signatures and need different responses.
The five kinds of leaf burn
| Type | What it looks like | When it happens |
|---|---|---|
| Sunburn | Bleached or papery patches on the most exposed leaves, worst on the western side | Heatwaves, especially after a cool spell |
| Wind burn | Browning along leaf edges, uniformly on the windward side | Hot dry inland wind, or persistent coastal wind |
| Salt burn | Brown margins working inward, often with a crusty residue | Coastal spray, bore water, or backwash from a pool |
| Fertiliser burn | Sharply defined brown edges within days of feeding | After applying fertiliser, especially to dry soil |
| Frost burn | Blackened or translucent soft growth at the top and outside | Clear still nights in winter |
Sunburn, the most common in Australia
Australian ultraviolet levels are among the highest in the world, and plants sunburn much the way people do. The damage is worst on new growth, on plants recently moved from a shaded nursery position, and after a cool cloudy stretch that leaves foliage unhardened when the heat suddenly arrives.
It shows as bleached, silvery or papery patches, usually in the middle of the leaf where the sun struck hardest rather than at the edges. Variegated plants burn first because the pale tissue has no protective pigment.
What to do: water deeply the evening before a forecast hot day, not during it. Provide temporary shade cloth over vulnerable plants through a heatwave. Move plants out of reflected heat from west-facing walls, light paving and glass. Do not strip every damaged leaf - they shade the growth beneath.
Wind burn
Hot dry wind pulls moisture from leaves faster than roots can replace it, and the leaf margins die back. Inland northerlies do it in a single afternoon; persistent coastal wind does it gradually. The tell is that the damage is uniform across the windward face of the plant rather than patchy.
What to do: establish a windbreak, or accept that the position needs a tougher plant. Hedging, a fence or a hardy screening row transforms what can be grown behind it.
Salt burn
Coastal gardens get salt on the leaves directly. Inland gardens get it through the soil from bore water or recycled water high in sodium. Either way it browns leaf margins and works inward, and it accumulates over time rather than arriving overnight.
Pool owners cause a version of this by discharging backwash into a garden bed. Salt-chlorinated pools produce genuinely salty water, and repeated dosing kills plants slowly.
What to do: rinse foliage with fresh water after strong coastal blows. Leach garden beds with a deep watering to flush salts below the root zone. Direct pool backwash to the sewer. In coastal front-line positions, plant species that genuinely tolerate salt rather than fighting it.
Fertiliser burn
Fertiliser salts draw water out of roots when applied too heavily or onto dry soil. The damage appears within days as sharply defined brown leaf edges, and it commonly follows someone feeding a struggling plant to help it recover.
What to do: water heavily to flush the root zone, and do not feed again until the plant is growing normally. In future, water before fertilising, use controlled-release products, and keep granules off the foliage and away from the trunk.
Frost burn
In Melbourne, Canberra, Adelaide Hills, Tasmania and frost-prone inland districts, cold damages soft growth on clear still nights. It appears as blackened or water-soaked tissue on the top and outer edges - the parts most exposed to the open sky.
What to do: leave the damage in place over winter, because it insulates the growth beneath it, then prune to live wood in spring. Frost cloth on forecast nights protects tender plants, and a position under eaves or tree canopy is measurably warmer than open ground.
Which plants burn most easily
- Variegated foliage - the white and cream tissue lacks protective pigment.
- Broad thin leaves such as hydrangea, Japanese maple and elephant ear.
- Recently planted stock that grew under nursery shade cloth and has not hardened off.
- Anything in a pot, because the root zone heats and dries far faster than garden soil.
- Plants against west-facing walls, glass or light-coloured paving, which reflect heat as well as light.
- Cool-climate species grown in warm districts, which are simply in the wrong place.
Preventing it
- Match the plant to the position. Most leaf burn is a siting problem rather than a health problem, and no amount of care fixes the wrong plant in a western aspect.
- Mulch to 50-75 mm, kept clear of stems. This does more for root temperature and moisture than any watering schedule.
- Water deeply and early. Morning watering hydrates the plant before the heat arrives; frequent shallow watering keeps roots near the hot surface.
- Harden off new plants. Give nursery stock a week in part shade before planting into full sun, particularly in summer.
- Watch the forecast. Shade cloth over vulnerable plants for two or three days of a heatwave prevents damage that takes a season to grow out.
- Feed onto moist soil, never dry, and follow the rates on the label.
Frequently asked questions
Will burnt leaves recover?
No. Burnt tissue is dead and will not turn green again. Recovery shows in new growth, which can take several weeks. Judge whether your fix has worked by watching the fresh foliage, not the damaged leaves.
Should I remove burnt leaves?
Not all at once. Damaged leaves still shade the stems and growth beneath them, which matters during an Australian summer. Remove them gradually as new foliage comes through, and after frost leave them until spring.
How do I tell sunburn from fertiliser burn?
Sunburn produces bleached patches in the middle of exposed leaves, worst on the western side of the plant. Fertiliser burn produces sharply defined brown edges on leaves all over the plant, appearing within days of feeding. The timing usually settles it.
Why did my plant burn when it has been fine for years?
Usually an unusually hot day combined with hot wind, or a cool spell that left the foliage soft before the heat arrived. Changes around the plant matter too - a removed tree, new light-coloured paving or a new window can all increase reflected heat significantly.
Can I prevent leaf burn in a heatwave?
Largely, yes. Water deeply the evening before, put shade cloth over vulnerable plants, avoid fertilising in the lead-up, and do not prune just before extreme heat, since fresh cuts and exposed inner foliage burn readily.
Is leaf burn a disease?
No. It is physical damage from heat, wind, salt, cold or fertiliser rather than an infection, so fungicides do nothing for it. If browning comes with spots, yellow halos or a spreading pattern, that is more likely disease and needs a different approach.
If it keeps happening
A spot that burns plants every summer will keep doing so. Rather than replacing the same plant repeatedly, choose species that suit the conditions - browse our hardy plants for tough spots, or sun tolerant plants for hot exposed positions.
Related reading: why plant leaves turn brown covers the wider diagnostic picture, and understanding windburn goes deeper on exposed and coastal sites.
